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Invasive Species to Know for the California Supplemental Exam (CSE)

Posted on by John

Invasive Species to Know for the California Supplemental Exam

Invasive plants are non-native species that infest natural ecosystems.

Scotch Broom -Cytisus scoparius is an invasive plant to know for the California Supplemental Exam (CSE) for landscape architects.

Scotch Broom (Cytisus scoparius) invades California landscapes throughout the state. Photo by Schaefer Rudolf

 

California’s mild climate is suitable for a lot of plants. Once introduced, these exotic plants survive and spread on their own without further human help. Frequently, invasive plants do not provide any benefit to the state’s wildlife. As a result, native plants must compete with these foreign invaders and habitat is lost.

As landscape architects, we take advantage of the enormous plant palate available in the state.

Although there is a growing state-wide preference for using native species in the landscape, many adapted exotic species serve important roles in contemporary landscape architecture. The state has not banned any of the following landscape plants. However, use caution when planting near natural areas.

Top 8 Statewide Invasive Plant Species for the CSE

Fennel is extremely invasive and well-adapted to coastal and foothill sites. Photo by John Tann. Know that fennel is invasive for the California Supplemental Exam for Landscape Architects (CSE)

Fennel is extremely invasive and well-adapted to coastal and foothill sites. Photo by John Tann.

The following landscape plants are widely adapted to California’s diverse habitats and landscapes. These species can naturalize in nearly any part of the state.

  • Tree-of-heaven—Ailanthus altissima
  • Scotch Broom—Cytisus scoparius
  • Tall fescue—Festuca arundinacea
  • Fennel—Foeniculum vulgare
  • English Ivy—Hedera helix
  • Dalmatian toadflax—Linaria genistifolia ssp. Dalmatica
  • Kentucky bluegrass—Poa pratensis
  • Black Locust—Robinia pseudoacacia

 

Invasive Species In Coastal Landscapes

Pampasgrass is invasive and adds fuel volume for wildfires.. Photo by Macleay Grass Man/Flickr.

Pampasgrass is invasive and adds fuel volume for wildfires.. Photo by Macleay Grass Man/Flickr.

California’s mild coastal climate is a particularly troublesome area for invasive species. Many common exotic species of landscape plants thrive a little too well along the coast and invade native landscapes. All of these plants are available from California nurseries. Use the following plants with caution near natural areas:

  • Black acacia—Acacia melanoxylon
  • Capeweed—Arctotheca calendula
  • Hottentot fig, iceplant—Carpobrotus edulis
  • Giant dracaena—Cordyline australis
  • Pampasgrass—Cortaderia selloana
  • Cotoneasters—Cotoneaster spp.
  • English hawthorn—Crateagus monogyna
  • Portuguese broom—Cytisus striatus
  • Cape ivy-Delairea odorata
  • Pride-of-Madeira—Echium candicans
  • Red gum—Eucalyptus camaldulensis
  • Tasmanian blue gum—Eucalyptus globulus
  • Edible fig—Ficus carica
  • French broom—Genista monspessulana
  • Licoriceplant—Helichrysum petiolare
  • Yellowflag iris—Iris pseudacorus
  • Ox-eye daisy—Leucanthemum vulgare
  • Sweet alyssum-Lobularia maritima
  • Crystalline iceplant—Mesembryanthemum crystallinum
  • Myoporum—Myoporum laetum
  • Olive—Olea europaea
  • Red fountaingrass—Pennisetum setaceum
  • Canary Island date palm—Phoenix canariensis
  • Castorbean—Ricinus communis
  • Peruvian peppertree—Schinus molle
  • Brazilian peppertree—Schinus terebinthifolius
  • Spanish broom—Spartium junceum
  • Athel tamarix—Tamarix aphylla
  • Big periwinkle—Vinca major
  • Mexican fan palm—Washingtonia robusta
  • Calla lily—Zantedeschia aethiopica

There are a few questions about invasive species on the California Supplemental Exam for landscape architects. Know the definition of an invasive species, the most noxious offenders, and the situations where plants that can invade native landscapes should not be used.

For more information on invasive horticultural plant species, check out How to Manage Pests

Pests in Gardens and Landscapes: Invasive Plants. You can find the page here.

 

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

 

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

 

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

 

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

 

Posted in Invasive Species, Plants

Fruitless Olive Trees for California Landscapes - California Tree Series

Posted on by John

Olives Without The Mess: Three Fruitless Olives for California Landscapes

Nothing evokes the romance of the Mediterranean like majestic olive trees. Their gray-green foliage and gnarled trunks are living sculptures in the garden. Olive trees are widely used in Spanish, Italian, and modern gardens.

Fruitless olive trees in the landscape are a possible test question on the California Supplemental Exam (CSE) for landscape architects

Olive trees in the landscape. Fruitless olives do not drop the messy fruit and require less maintenance in the landscape. Photo by Seán A. O’Hara.

Olive trees also produce tasty table olives and delicious olive oil. However, there is a dark side lurking in the canopy of any average olive tree. While foodies salivate at the thought of delectable olive, the messy fruit is a major nuisance in the landscape.

Olive pollen is also vilified because it causes allergy-sufferers weeks of agony in the spring. The wind-borne pollen is light and travels great distances, much to the dismay of many sensitive people.

 

Fruitless olive tree used as a focal point in a formal garden. Photo by Olive trees in the landscape. Fruitless olives do not drop the messy fruit and require less maintenance in the landscape. Photo by Seán A. O'Hara.

Olive Tree used as a focal point in a formal garden setting. Photo by Seán A. O’Hara.

Don’t despair. Select fruitless olive trees for your next planting plan to get that classic olive look without the maintenance nightmare of messy fruit and allergy-producing pollen.

Fruitless Olive Varieties

Landscape architects can choose from three popular fruitless olive cultivars.

  • ‘Swan Hill’ Fruitless Olive
  • ‘Majestic Beauty’ Fruitless Olive
  • ‘Wilsonii’ Fruitless Olive

Let’s get a closer look at what each of these varieties of fruitless-olive have to offer the California landscape architect.

Olive trees frame an Italian-inspired garden. Photo by Seán A. O'Hara.

Olive trees frame an Italian-inspired garden. Photo by Seán A. O’Hara.

‘Swan Hill’ Fruitless Olive

 

'Swan Hill' olives tolerate reflected heat and grow well in large containers. Photo by Swan Hill Nurseries.

‘Swan Hill’ olives tolerate reflected heat and grow well in large containers. Photo by Swan Hill Nurseries.

The ‘Swan Hill’ fruitless olive grows and looks like a normal fruiting olive but does not produce the messy fruit. Since the tree doesn’t expend energy making fruit, it grows a little faster than fruiting olive trees and can reach 30 feet tall and spread its leafy canopy up to 35 feet in only 15 years. And unlike fruiting olives, ‘Swan Hill’ only releases 1% of the pollen other fruiting olives spread in the spring.

‘Swan Hill’ olives are available in 24″ to 60″ boxes. Landscape architects can specify true multi-trunked trees, low-branched trees, or single-trunked standards depending on the effect needed for the site.

‘Majestic Beauty’ Fruitless Olive

'Majestic Beauty' olive is a nearly fruitless olive tree introduced by Monrovia Nursery.

‘Majestic Beauty’ olive is a nearly fruitless olive tree introduced by Monrovia Nursery.

The ‘Majestic Beauty’ fruiting olive was introduced by Monrovia Nursery and was the first commercially-available fruiting olive. ‘Majestic Beauty’ has an upright growth habit and an open, airy canopy that is ideal for parking lots and pedestrian areas. The foliage is olive-green above and has silvery undersides. Occasionally, a few fruit will develop on the branches, but the tree is essentially fruitless.

‘Wilsonii’ Fruitless Olive

'Wilsonii' fruitless olive trees are nearly fruitless and are useful, low-water trees for California landscapes.

‘Wilsonii’ fruitless olive trees are nearly fruitless and are useful, low-water trees for California landscapes.

The ‘Wilsonii’ fruitless olive is a genetic mutation of the fruiting ‘Manzanilla’ olive tree. This fruitless olive typically grows 25 to 30 feet tall with an equal spread. The crown is dense and has willowy gray-green foliage. Once in a while, a few fruit are produced. Growth is slow to moderate. Tolerates desert heat and cold. Vary similar to ‘Majestic Beauty’.

Growing Fruitless Olives

Olive trees are native to the Mediterranean region of Europe and north Africa and adapt quite well to most of California.

The Sunset Western Garden Book suggests planting olive trees in Sunset Climate Zones 8,9 and 11-24.

Olives grow well in the desert and can tolerate some frost. Growth is slow to moderate.

Along the coast, olives require low amounts of supplemental irrigation. Moderate amounts of irrigation improve growth in inland valleys and the desert.

Olives can be planted in lawn areas as long as the soil drains well and the tree’s crown is slightly raised.

Olive Trees and the California Supplemental Exam

The California Supplemental Exam (CSE) for landscape architects has several questions about plant material that is adapted to California’s dry climate. Some benefits that olive offer California landscapes is that they are evergreen trees, use low to moderate amounts of supplemental water, and are generally free of serious pests and diseases in the landscape. These three factors qualify olive trees as “adapted plants” under the California’s green building code (CALGreen).

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

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California Turf for the California Supplemental Exam

Posted on by John

Know Your California Turf for the California Supplemental Exam

Turf is a common design element in many California landscape designs. Landscape architects can specify many kinds of turfgrass for their projects. Picking the right grass can ensure a successful project while the wrong grass and be an absolute failure. Let’s review California’s most common turfgrasses.

Common Turfgrass Species for California

  • Bermudagrass (common and hybrid)—Cynodon spp.
  • Kentucky bluegrass—Poa pratensis
  • Perennial ryegrass—Lolium perenne
  • St. Augustinegrass—Stenotaphrum secundatum
  • Tall fescue—Festuca arundinacea
  • Zoysiagrass—Zoysia spp.
Main lawn at Lotusland. Photo by J. Books.

Main lawn at Lotusland. Photo by J. Books.

Warm-Season Versus Cool Season

Turfgrasses are classified as either warm-season or cool-season.

Warm-season lawns grow vigorously during the hottest months and are dormant in winter. In summer, the lawn looks rich and verdant. In winter, the grass turns tan because the top growth goes dormant. Warm-season can be overseeded with annual turfgrass seed in autumn so that the lawn has year-round green color. Zoysiagrass, St. Augustine, and Bermudagrass are all warm-season turfgrasses.

Cool-season grasses grow best in spring and fall and are dormant or semi-dormant during the hottest part of the summer. With adequate water, cool-season grass can stay green in summer even if it is dormant. Tall fescue, perennial ryegrass, and Kentucky bluegrass are cool-season turfgrasses.

Right Grass, Right Place

All of these grasses perform well in California under the right conditions.

Sun

Most grasses require at least six to eight hours of direct sun to thrive. But, some grass species can tolerate some shade and still look acceptable in the landscape.

These turf species are listed in order of shade tolerance.

  1. Red fescue (Festuca rubra)
  2. St. Augustinegrass
  3. Zoysiagrass
  4. Tall Fescue
  5. Kentucky Bluegrass
  6. Perennial ryegrass
  7. Bermudagrass

Red fescue and St. Agustinegrass are the most shade tolerant turfgrass species. Bermudagrass is the least shade tolerant and looks very poor in shade.

Water Use

Santa Barbara Mission Lawn Around Fountain - Lawn is a unifying element in the landscape. Photo by Rachel Titiriga.

Lawn is a unifying element in the landscape. Photo by Rachel Titiriga.

Cool season turf requires more irrigation than warm-season turfgrass. According to the Water Use Classification of Landscape Species (WUCOLS), cool-season turf requires 90 percent of a site’s reference evapotranspiration rate (ETo). On the other hand, warm-season turf only requires 70 percent of ETo. Therefore, warm-season turf uses less water than cool-season turf.

Some grasses naturally resist drought better than other species. The most drought grasses are on top of the list while the thirstiest species hover at the bottom.

  1. Hybrid bermudagrass
  2. Zoysiagrass
  3. Common bermudagrass
  4. St. Augustinegrass
  5. Tall fescue
  6. Kentucky bluegrass
  7. Perennial ryegrass

Heat Tolerance

Santa Barbara County Courthouse lawn in the sunken garden. Photo by LA WAD/Flickr.

Santa Barbara County Courthouse lawn in the sunken garden. Photo by LA WAD/Flickr.

Warm-season turfgrass is more heat than cool-season turfgrass. This list arranges turf species by heat tolerance with the most heat-tolerant species at the top of the list.

  1. Zoysiagrass
  2. Bermudagrass
  3. St. Augustinegrass
  4. Tall fescue
  5. Kentucky bluegrass
  6. Perennial ryegrass

Turf Texture

Leaf texture may be an important design factor for a particular project. Turfgrass with wider leaf blades create a coarser texture. Narrow-leaved turfgrass species add a fine-textured look to the landscape. Here is a list of turfgrass varieties order from coarsest to finest texture.

  1. St. Augustinegrass
  2. Zoysiagrass
  3. Tall fescue
  4. Common bermudagrass
  5. Kentucky bluegrass
  6. Perennial ryegrass
  7. Hybrid bermudagrass
  8. Red fescue

The Bottom Line

Turfgrass is a useful plant in the landscape. A well-maintained lawn is great playing surface for pets and children. Many athletes strongly prefer real turf over modern artificial turf substitutes. While turf does consume lots of water, proper species selection and efficient irrigation can reduce turfgrasses environmental impact.

Be prepared to answer a question or two about turfgrass selection or irrigation on the California Supplemental Exam for landscape architects.

Posted in Irrigation, Plants, turf

Fern + Pine = Podocarpus? California Tree Series

Posted on by John

Fern + Pine = Podocarpus?

California Tree Series

Fern pine is the common name for plant that is neither a fern nor a pine. Other common names for Podocarpus gracilior are Podocarpus, African fern pine, and yew pine.

Photo by Josh Jackson.

Podocarpus gracilior - Fern Pine - California Supplemental Exam for Landscape Architects

Podocarpus gracilor is a common exotic evergreen tree that adds a touch of softness to the landscape.

Fern pine is an adaptable evergreen trees that grows to 20 to 60 feet tall and spreads 10 to 20 feet wide at maturity.

Leaves of fern pine are needle-like but are not true needles.

Fern pines are not grown for their flowers (they are extremely tiny). male and female flowers are borne on separate plants. Female plants will bear small, fleshy fruit after many years if male plants are nearby.

Landscape Use Podocarpus is often planted as screens or background plants.

Podocarpus gracilior - Fern Pine - California Supplemental Exam for Landscape Architects

Fern Pine. Podocarpus gracilior in the landscape. Photo by Josh Jackson

They can be grown as:

  • street trees
  • lawn trees
  • patio specimens
  • garden trees
  • hedges or tall screens
  • large containers

Their limber branches also lend themselves to espalier.

Landscape architects like fern pine because it is one of the cleanest and most reliable trees or shrubs.

The method of propagation determines fern pine’s growth habit. Seed-grown plants are more erect than willowy cutting-grown plants.

Growing Conditions

Sun is not an issue for fern pine since it grows equally well in sun or shade.

Podocarpus gracilior - Fern Pine - California Supplemental Exam for Landscape Architects

Photo by Josh Jackson.

They do well in areas with full sun or part shade. Fern pines are tolerant of most soil types but may display signs of chlorosis in alkaline, heavy, or damp soils.

Moderate water use.

Recommended for Sunset climate zones 8-9 and 13-24.

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

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What’s a Zelkova? California Tree Series

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Japanese Zelkova (Zelkova serrata) Street Tree for CaliforniaWhat’s A Zelkova?

Zelkova, Japanese zelkova—Zelkova serrata

Japanese zelkova is a deciduous shade tree or street tree that grows well in many parts of California.

After Dutch elm disease wiped out most of the majestic American elms, landscape architects began searching for a disease-resistant alternative. Zelkova serrata is a good alternative to American elm and has many of the same desirable qualities.

Japanese Zelkova (Zelkova serrata) Street Tree for California

Japanese Zelkova is a deciduous tree. The narrow, oval leaves have a toothed margin reminiscent of true elms. Foliage is medium green in color. Autumn’s cooler weather brings colorful changes to the foliage. Leaves turn from green to yellow (most common), red, or brown in fall. The bark is smooth and medium-gray in color. In winter, the bare branches display an interesting branch pattern.

Japanese Zelkova (Zelkova serrata) detail of leaves

Use Japanese Zelkova as a shade tree or street tree. This species can also be effectively used in parks and larger landscapes as a medium-sized tree. Use in the same way that American elms were used generations ago. Some municipalities also encourage Japanese Zelkova to be used to replace the disease-prone American elm in new plantings in historic districts and older neighborhoods.

Japanese Zelkova (Zelkova serrata) Fall Color in the Landscape

Japanese Zelkova is a moderate water use plant and needs regular irrigation. Best growth occurs in full sun but trees also tolerate partial shade. Minimal pruning is required; correct weak branches as necessary for proper development and public safety. Few serious pest and diseases affect well-grown, healthy trees. Grows moderate to fast; 60 feet tall with an equal spread.

Japanese Zelkova (Zelkova serrata) Fall Color in the Landscape

Plant Japanese Zelkova in Sunset climates zones 3-21, 29-41.

Study for the California Supplemental Exam a new way!

Practice Problems for the California Supplemental Exam for Landscape Architects Study Guide

Practice Problems for the California Supplemental Exam for Landscape Architects Study Guide

Use “Practice problems for the California Supplemental Exam for Landscape Architects” to help you pass the CSE the first time.

Test your knowledge with over 360 questions based on knowledge, skills, and abilities that are on the CSE exam.

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What’s The Best Native Pine Tree For California Coastal Areas?

Posted on by John

What’s The Best Native Pine Tree For California Coastal Areas?

California has many native pine trees, the best pine tree species is the Torrey pine.

 

Torrey Pines in the Wild. Pinus torreyana is the best native pine for southern California.

Photo by Daniel Orth.

Native to only a small part of the coastal strand and Channel Islands in San Diego County. The Torrey Pine thrives in coastal conditions and is native to the coastal sage scrub and chaparral plant communities. It is also the rarest native pine species that probably was much more widespread in previous centuries.

The Torrey pine is highly regarded in its native range. In fact, the City of Del Mar requires landowners to get a permit to cut down a Torrey pine tree.

Torrey Pine Description

Torrey pine needles

Photo by Brian Dearth.

Needles are long and grayish green. The needles on vigorous specimens may grow to 13 inches long, but average trees grow to around 9 inches. The long sparse needles form an irregular open canopy that allows filtered sunlight through to the plants growing underneath. The 6 inch green pinecones matured to a chocolate-brown color. The trunk is covered in plated bark.

Trees grow between 40-70 feet tall and spread up to 35 feet wide.

Torrey pine is adapted to low-water ornamental landscapes in Sunset Climate Zones 8, 9, and 14-24. Hardy to 15 degrees.

In the WUCOLS manual, Torrey pine is rated as a low water use plants near the coast. Water once or twice a month during summer.

Where to Plant

Torrey Pines at Torrey Pines State Reserve

Torrey Pines at Torrey Pines State Reserve

Plant in full sun or light shade for best results. In the wild, the Torrey Pines grow in sandy coastal soils. As you might’ve guessed, it needs adequate drainage around the roots. Avoid planting lawns since they require more water than the tree can handle. Use in low-water landscapes. Irrigated trees grow considerably faster than trees in the wild.

Landscape Uses

Use Torrey pine as an evergreen screen or as a specimen tree. The open canopy allows users to see some view through the needles. This pine tree species can also tolerate windy sites.

Availability

Torrey Pines is available from native plant specialist. In recent years, the Torrey pine has become more common in nurseries. Avoid planting root bound specimens since they can be easily girdled if left too long in the container at the nursery.

Las Pilitas and Tree of Life nurseries sell Torrey pine trees in five and fifteen gallon containers.

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

 

Posted in Plants Tagged with: , , , , , , ,

Top 10 Poisonous Plants for Horses and Livestock

Posted on by John

Do You Know Which Plants Can Kill Horses?

Horses, goats, sheep, and other animals eat plants for food. However, not every plant is safe for even the most robust herbivores. Lots of plants make animals (and people) sick. But some plants can kill.

Horses on a hill. Horses can die if they eat too much toxic plant material

Photo by Lindsay Shaver

Toxic Plants

Not all plants are equally toxic. Some plants are only toxic if a large quantity is eaten by the animal. For example, hemlock is toxic to a horse if only four or five pounds of leaves were eaten by the animal. On the other hand, a single mouthful of yew (Taxus spp.) can kill a horse. Some plants are more toxic than others and their effects on the animal are more noticeable.

Occasionally, the California Supplemental Exam for landscape architects will include a question or two about what kind of plants are safe to use around an equestrian trail. This list will help you understand which plants can cause trouble for our four-legged companions.

These are the most dangerous plants for horses and other livestock.

  1. Water hemlock (Cicuta spp.)
  2. Yellow star thistle/Russian knapweed (Centauria spp.)
  3. Yew (Taxus spp.)
  4. Johnsongrass/Sudan grass (Sorghum spp.)
  5. Locoweed (Astragalus spp. or Oxytropis spp.)
  6. Oleander (Nerium oleander)
  7. Red maple trees (Acer rubrum)
  8. Bracken fern (Pteridum aquilinum)
  9. Hemlock (Conium maculatum)
  10. Tansy ragwort (Senecio spp.)

Some of these plants are wild species and grow in pastures. Other, such as oleander and red maple, are common ornamental species and are widely planted in parts of the state.

Lets look at each species in more detail.

Water hemlock (Cicuta spp.)

Water Hemlock Is Toxic to Horses

Water hemlock flowers. Photo by SCCF Nursery

Water hemlock is a close relative of poison hemlock and can kill animals if only a few pounds are eaten.

Water hemlock is considered one of the most toxic plants in the United States.

Water hemlock is a perennial plant that has six-foot tall stems topped with flowers. All parts of the plant are toxic and have a powerful neurotoxin that causes a variety of maladies including respiratory failure. This is one of the most dangerous plants for humans and animals.

Yellow Star Thistle/Russian Knapweed (Centauria spp.)

Yellow star thistle is an invasive annual weed of Eurasian origin. The spiny foliage and yellow flowers make it easy to spot along roadsides and in fields. It is more common in interior areas of the state and grows well in infertile, disturbed soils. Horses and other animals are cumulatively poisoned by this plant and must eat half or more of their body weight of this particular weed before showing symptoms of poisoning. The plant has a toxic agent that has a neurological effect on the brain that inhibits the nerves and control chewing. There is no treatment for the neurological damage caused by yellow star thistle.

Yew (Taxus spp.)

Yew is a common landscape plant in the northern part of California. There are also a couple of native species that grow in the Coastal Ranges and Sierra Nevada mountains. Yew is used by landscape architects for its great architectural lines, deep green color, and nice texture. However, this good-looking plant has a dark side. The foliage (and to a lesser extent, the berries) are highly toxic to horses and humans. If a horse eats only a few ounces, it could be dead. Yew has toxic compounds in the foliage that contain taxine, an alkaloid that causes respiratory and cardiac collapse. The effects of yew poisoning are immediate and irreversible.

Johnsongrass/Sudan grass (Sorghum spp.)

Johnsongrass is a seductive plant for herbivores. The grass grows up to six feet tall and has a wide blade. Johnsongrass is an invasive weed in California and is commonly found growing in moist spots and drainage ditches in agricultural areas of the state. Cyanide poisoning can happen when the foliage is eaten by animals. Always consult with a veterinarian if you suspect Johnsongrass poisoning.

Locoweed (Astragalus spp. or Oxytropis spp.)

Loco means “crazy” in Spanish. As you might guess, animals start behaving strangely after eating this plant. While it may be desirable to remove locoweed from the area, some species are protected by federal and state law. Poisoning is cumulative and the plant has a toxin that interferes with the body’s ability to process sugars.

Oleander (Nerium oleander)

Nerium oleander is toxic to horses and other herbivores. Photo by Leonora Enking

Nerium oleander is toxic to horses and other herbivores. Photo by Leonora Enking

More horses and other livestock are killed by eating oleander than any other toxic plant. Oleander is a common ornamental plant in California. Do not plant oleander near areas where horses are kept or ridden.

About 30 to 40 leaves can be deadly to a horse.

It does not take much foliage to poison a large mammal. The effects of start in a couple of hours and can last more than one day. With immediate care from a veterinarian, the effects can be reduced.

Red maple trees (Acer rubrum)

Red maple is an exotic shade tree that is widely planted in cooler areas of the state and is appreciated for its brilliant fall color. Fresh foliage is not much of a hazard for horses. However, wilted foliage has chemical compounds that affect the blood system. Horses usually encounter wilted red maple foliage after a storm breaks branches and the leaves begin to wilt. The survival rate depends on how much foliage was eaten by the horse and the amount of supportive care available.

Bracken fern (Pteridum aquilinum)

Bracken fern and its relatives are commonly found in open forests or fields in the mountains of northern California. While most horses will usually find something more appetizing, some animals seem to develop a taste for bracken fern and will seed it out even when other dining options abound. Fern fronds contain a chemical that prevents the animal from absorbing vitamin B1. Fortunately, a horse must eat hundreds of pounds of the foliage before the effects become severe.

Poison Hemlock (Conium maculatum)

Poison hemlock is a perennial weed found in pastures and roadsides throughout the United States. As the name suggests, the plant is quite toxic to humans and animals. Only a few pounds of the foliage and stems can lead to death from respiratory failure. The signs start to appear in just a couple of hours and the survival rate depends on the amount of plant that was eaten by the animal. Children have been killed by the toxic effects of this plant. Usually, kids will use the hollow stems as “pea shooters” and are poisoned when they put the stem in their mouth.

Tansy ragwort (Senecio spp.)

Tansy ragwort is a widespread weed with many species native to California and the western United States. While the toxicity varies from species to species, all members of the genus have toxic alkaloid compounds that cause liver damage if a large amount of the plant is eaten.

What Can Landscape Architects Do To Prevent Poisoning Animals?

Avoid planting these plants near areas where horses or other livestock could come into contact with the foliage. Maintenance personnel can help keep the invasive weeds in check and reduce the chance that horses will eat some of the wild toxic plants.

For a more thorough discussion, please read “10 Most Poisonous Plants for Horses” at EQUUS magazine’s website.

Read more about toxic plants and planting design safety in “Pass the California Supplemental Exam for Landscape Architects” and “Practice Problems for the California Supplemental Exam”.

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

 

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What Is Kiln-Dried Lumber?

Posted on by John

What Is Kiln-Dried Lumber?

Landscape architects can specify several different types and grades of lumber for landscape construction. Two common forms construction-grade lumber are green lumber and kiln-dried lumber.

Green Lumber

Green lumber has an average moisture content above 19 percent. As green lumber dries, it can shrink, warp or twist. Green lumber is usually less expensive than kiln-dried lumber and can be used where movement will not weaken a structure or wreak havoc on a design detail.

Kiln-Dried Lumber

Kiln-Dried lumber has a much lower moisture content than green lumber.

In the case of kiln dried lumber, the wood is dried in giant kilns with carefully controlled temperature and humidity levels. The goal is to get the boards to dry quickly and evenly, and to prevent warping that could render the wood unusable. The alternative is air drying, in which lumber is allowed to sit in a breezy area so that it loses moisture and contracts. Air drying tends to take longer, and it brings the moisture content closer to 15% than the desired 6% to 8%. —Source: Wise Geek

As a result, kiln-dried lumber will move less during and after construction.

Kiln-dried lumber is marked with a grade stamp that indicates the lumber has been dried before leaving the sawmill.

Lumber Grade Stamps

Lumber Grade Stamp

Kiln-dried lumber will be stamped with the mark “KD” or “SDRY”. If the lumber is imported, it will also be heat-treated to kill any pests. Imported wood is marked “KD-HT” to indicate that it is dried and heat treated. All kiln-dried wood will also have a certification mark which indicates which organization’s standards which the wood complies.

Some other abbreviations that you may notice on the lumber is the mill code and the species mark.

The following species are organized from strongest to weakest:

  1. Doug Fir, D Fir-L: Douglas fir (L=western larch)
  2. SYP: Southern pine
  3. Hem, Hem-fir, H-F: Hemlock or fir
  4. S-P-F: Spruce, pine, or fir

Kiln-dried wood moves less and is preferred for structural work. While kiln-dried wood is useful for some applications in the landscape, pressure-treated wood is more commonly used where exposure to moisture or soil are likely.

The California Supplemental Exam has several questions on construction detailing and questions about wood may be on the exam. Know the common wood species used for landscape construction and their properties.

What Would It Mean To You If You Could Walk Into The Exam Full Of Confidence?

Now, there are resources to help you prepare for the CSE exam.

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

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Three Reasons Why Retaining Walls Fail

Posted on by John

Do you know the three ways restraining walls fail?

Retaining walls are useful engineering solutions landscape architects use to create useable space on sloping or hilly landscapes.California’s unique terrain creates lots of opportunity for creative landscape architects to use retaining walls as a design element.

Different types of common retaining walls.

Different types of common retaining walls.

Expect a couple of questions about retaining walls on the California Supplemental Exam

According to Wikipedia, “A retaining wall is a structure designed and constructed to resist the lateral pressure of soil when there is a desired change in ground elevation that exceeds the angle of repose of the soil.”

Retaining Wall Description

Retaining Wall Description

Landscape architects are limited to designing walls that have up to three feet (3′) of exposed wall height. While the level and complexity of engineering is minimal for a wall this size, design principles can prevent three common reasons for failed retaining walls.

Retaining walls are great when the work as designed. However, the forces of nature and laws of physics can work against even the best engineered retaining walls. These forces can cause catastrophic failure.

3 Ways Retaining Walls Fail

  • Overturning
  • Sliding
  • Settlement of the foundation

Overturning

Overturning is caused by the force of the soil pushing a wall over when the thrust exceeds the wall’s weight. Overturning can be prevented by increasing the wall mass, enlarging the foundation, or using a cantilevered foundation. Retaining Walsh that hold back a surcharge are more likely to fail than walls that do not retain a surcharge.

Sliding

Sliding is also caused by the thrust of the soil. Instead of the wall overturning, it slides horizontally as an entire unit. Larger foundations, more massive walls, or cantilevered foundations are some solutions that can reduce the chances of a wall sliding. Ensure that there is a drainage system installed behind the wall to reduce hydrostatic pressure.

Settlement of the Foundation

Settlement of the foundation happens when the weight of the wall causes the soil to compress or subside. When this happens, the height of the wall above grade shrinks. Settlement can encourage other weaknesses as well.

However, good design and construction practices can help prevent settlement. These things can ensure a strong wall:

  • Compaction
  • Undisturbed sub-grade
  • Strengthen sub-grade with gravel

Compaction—Landscape contractors will compact the soil before laying the foundation. Compacting soil reduces the pore space between soil particles and creates a denser substrate for a retaining wall foundation. Double-check your details and specifications to ensure that they specify that the soil under the footing will be compacted during construction.

Undisturbed Sub-grade—Landscape architects are limited by state law and regulation as to the height and engineering features of retaining walls. Any retaining wall that landscape architects design should have a footing in du disturbed sub-grade. That means avoid building walls on fill soil. Even the best engineered fill soils lack the strength of average undisturbed soil. Only civil or structural engineers can design a retaining wall footing for fill soil conditions. As landscape architects, we will keep our footings in undisturbed soil.

Strengthen Sub-Grade With Gravel—Weak or expansive soils can be strengthened by placing several inches of gravel, aggregate, or crushed stone under the retaining wall foundation. Gravel is dimensionally stable and can withstand the compressive forces of the wall structure. Be sure to note that the gravel base should be compacted.
Multiple tiered retaining walls

More About Retaining Walls

Landscape Architectural Graphic Standards is an excellent resource for every landscape architect. Some of the information in this article was inspired by the soil mechanics section.

Read more about retaining walls in “Pass the California Supplemental Exam for Landscape Architects” and “Practice Problems for the California Supplemental Exam”.

What would it mean to you if you could pass the California Supplemental Exam for landscape architects the first time?

With the right preparation, you can pass the exam the first time and get that landscape architect license you deserve.

CSE Pro Package - Best resource for the California Supplemental Exam for landscape architects

Take your exam preparation to the next level with the “CSE Pro Package”. Get the only “unofficial” study guide for the CSE and the practice problems book today. Read More…

 

Posted in Construction, Soil Tagged with: , , , ,

Six Things To Consider For A Landscape Lighting Plan

Posted on by John

Understanding Landscape Lighting For The CSE:

Part 2: Six Things To Consider For A Landscape Lighting Plan

Landscape lighting is as much of an art as it is a science.

Before designing a landscape lighting plan, there are six things a landscape architect should consider.

  • Client goals and objectives
  • Ambient light levels
  • What materials and objects going to be illuminated
  • What types of plants will be illuminated
  • What should not be lit
  • Applicable laws, regulations, and codes

Let’s look at each item in more detail.

What Are The Client Goals & Objectives?

Landscape architects must first consider the client’s goals and objectives for the site at night. The client may have several competing goals in mind. For some clients, safety and security are the primary goals. Other clients may want to emphasize the architectural qualities of the site’s buildings and landscape features. The intended nighttime site use determines how the site will be illuminated.

Questions to ask the client early in the design phase include:

  • Who is the nighttime audience or target user?
  • Where will the space be viewed at night?
  • Will site visitors only view the space or navigate through the site?
  • How will the space be used at night?
  • What is the most important feature or critical focus?

What is the Site’s Ambient Light Level?

The site’s ambient light levels influences the amount of additional light that the designer will use to achieve the desired lighting effect. Existing site lighting, street lighting and lighting from adjacent properties all may affect the ambient light level.

What Materials & Objects Will Be Illuminated?

Before a landscape architect can start to design a landscape lighting plan, he or she needs to identify which objects or spaces need to be illuminated. Determine the design’s focal points are circulation system before beginning the lighting design.

Consider the color and materials of the objects you are going to illuminate. Rough-textured objects can be accentuated with some illumination techniques. Dark surfaces will require more light than lighter objects. A savvy designer will find gather useful information early on in the design process.

What Types of Plants Will Be Illuminated?

Plants can have a dramatic affect on the final lighting design. Trees can be up-lit, down-lit, cast shadows, or silhouetted. Landscape lighting effects can take advantage of interesting forms or textures of plants in the landscape.

What Should Not Be Lit?

Not every item in the landscape needs to be illuminated. Determine which objects do not require illumination for safety or as an accent in the landscape. Light trespass and light pollution are other things to avoid. Keep the light on your site and off of adjoining properties. Use cutoff fixtures to direct away from the sky and towards the ground to prevent light pollution.

What Are The Site’s Applicable Laws, Regulations, & Codes?

Determine the regulatory framework for the site before you begin the design. In California, Title 24 of the Energy Code restricts the amount of power that exterior lighting can consume. Additionally, the site’s “Light Zone” affects the amount of light than can be used based on the land use and density. Other codes include the California Electric code and codes that apply to swimming pools if water features are to be illuminated. Additionally, local codes can add layers of restrictions and complexity to the process.

Before starting a lighting plan, it is critical to determine the site’s and client’s goals and objectives. Determine what features will be illuminated and what not to light. And finally, determine energy restrictions that affect the lighting design.

Landscape Lighting & the California Supplemental Exam for Landscape Architects

Lighting is an important health, safety, and welfare issue for California landscape architects. As a landscape architect candidate prepares to take the California Supplemental Exam (CSE), they need to understand the basics of landscape lighting as it relates to the public’s safety and energy conservation.

If you missed Part 1 of this series, check it out here.

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Do You Want to Pass the CSE?

You are in the right place. Learn what you need to pass the California Supplemental Exam for landscape architects the first time. This site is dedicated to aspiring landscape architects who want to get a California landscape architect license. I'll share my research for the CSE as I prepare for the exam.

Feel free to submit a question and I'll do my best to answer it here.

Good luck,
John

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