- Author: Flo Pucci, Master Gardener
As our cities and towns continue to sprawl, an increasing number of Californians live in the urban-wildland interface where the threat of fires is particularly significant. The urban-wildland interface is the area where urban and suburban development meets underdeveloped areas containing natural vegetation. These areas can be a beautiful place to live, but they are not without the risk of wildfires. When conditions are windy and dry, the grasses, brush, trees, or other vegetation surrounding a home becomes a dangerous fuel source which can be quite flammable during the hot summer and early fall months. California's native vegetation has evolved in response to wildfire, and many species depend upon periodic burns for rejuvenation or reproduction. Because of this, many structures are destroyed by wildfire every year within the jurisdiction of CAL FIRE.
However, homes are being saved because of homeowners' careful implementation of techniques that increase the fire safety of their landscape which minimizes the ignition of vegetation. As a result, the fire resistant landscape has become a hot topic for homeowners who live in Northern and Southern California where danger is especially prevalent in hills and wooded areas.
A prudent homeowner will want to follow safety precaution practices concerning the location of plants and building material that can compromise the home in the event of a wildfire. As a rule of thumb, homeowners need to make sure that fire moving toward their property cannot follow a continuous path through vegetation. With this in mind, the "fire ladder" concept is essential, especially near structures where the fire reaches shrubs or limbs below the canopy and can 'climb the ladder' and expand from ground level to tree canopy. These vertical columns of vegetation provide a continuous fuel supply that enables fires to spread rapidly throughout the landscape.
Thus, it is recommended that trees with significant canopy be planted at far enough distances from a house so horizontal branches do not carry their foliage within ten feet of the structure. Lower branches of trees should be pruned regularly, and nothing should be growing below the canopy of trees. Deciduous trees are generally more fire-resistant than evergreen because they have higher moisture content in their leaves. Further, arrange landscape features in horizontal and vertical spaces to disrupt the fire. Periodically reduce fuel loads by thinning trees and shrubs or heavily pruning species that can re-sprout from basal burls.
Experts do agree that beneficial practices implemented in a high-fire area such as: removing dead vegetation branches; selectively thinning woody plants and keeping vegetation away from the roofs and eaves of any buildings; and replacing building materials that are an invitation to disaster, such as wooden shingles, siding, and decks, are vital to safeguard a property.
Only vegetation that does not ignite easily should be planted in this area. Only fire-retardant plants should be planted with 50 to 75 feet of a home or structure. Also, this provides not only an essential aesthetic element in the garden, but also delivers small buffer zones making it more difficult for a fire to travel horizontally, leaping from plant to plant.
When appropriate, maintain a greenbelt of moisture-retentive, low-growing vegetation in a 30-foot wide strip surrounding the home. For example, healthy lawns, ground covers, and perennials form a greenbelt in the home defense zone. So, a defensible space is only part of a broader landscape management strategy designed to protect and defend a property from wildfires. Similarly, a fire zone can be created by using stone walls, patios, gravel, and roadways.
To design a fire-resistant landscape, choose features like mulch, pavement, planters, and plants. In fact, there are conflicting opinions regarding which plants are fire-safe versus which are highly flammable. Some plants are described and marketed as fire-resistant; yet it is essential to remember that, in view of certain conditions, all plants can burn regardless of how they are classified. When choosing plants for a fire-safe landscape, select plants with high moisture content in leaves, as they ignite and burn more slowly. Make sure that plants are small and broken in clusters in a mosaic pattern. Some native plants, such as chamise and exotic eucalyptus, have been identified as poor choices for home landscapes at the wildland's edge.
However, how plants are maintained and where they are placed is as important as the species chosen. Cultural practices and landscape management have a greater impact on whether a plant ignites than does the species.
Carefully choose where to place plants or garden beds that will need mulch. Mulches are beneficial because they retain moisture, reduce weed growth, and cover up weed cloth. However, be mindful not to use too much bark mulch in garden beds near the home or outbuilding. In general, particles or stringy mulches smaller than a ¼ inch ignite and burn more rapidly that large chunks. Limit leaf litter and mulch layers to four inches in depth.
Additionally, when exposed to fire, thick mulches greater than 2 inches deep tend to smoke and are hard to put out. Do not place wood or use bark mulches within 3 to 5 feet of the house. Instead, consider colored rocks or other less-flammable materials.
Cut back grasses and wildflowers as they brown, although the homeowner may want to leave some patches for seed harvesting, reseeding, or wildlife. Maintain landscape features by keeping plants alive, healthy, and well pruned. Concentrate on removing dead and diseased wood as needed, at least annually. Do not allow debris to accumulate near the home and avoid invasive weedy plants that may take over an area near the house.
Furthermore, drip irrigation systems are effective and conserve water because they target where the water goes and control the quantity. Use sprinklers for lawns and ensure that the grass is getting enough water to keep it green, healthy, and thereby fire resistant. Also, it would be useful (cost permitting) to install an independent irrigation valve with sprayers that can water the area around a home in the event of a fire. Realize however that in a firestorm, everything will burn.
Consequently, proper and careful planning of a home landscape can yield a beautiful garden and a fire-safe home by the implementation of techniques such as a green belt around the property. Removing dead vegetation and branches, selectively thinning woody plants, keeping vegetation away from roofs and eaves, replacing flammable building materials, and using landscape features that increase the fire-safety of property are all practices that enable the fire department to access and defend your home in the event of a wildfire (Cal Fire).
For more information about this topic please visit the links below.
- Author: Sue Davis, Master Gardener
The long, lazy days of summer just beg us to come outside and play in the garden. Although there are just four “chores” per month in this article, it is easy to find more to do as we spend extra time outside.
ONE –How often to water trees in the landscape during the summer months is always a question. For a quick reference: Do not water mature, native California oaks. If the whole area under the tree cannot be kept dry, keep the water at least 10 feet from the trunk to avoid root rot. Deep watering only once per month works for mature, drought tolerant trees while a deep irrigation every 14 days is good for mature fruiting and most ornamental trees growing in clay-loam soil. Other types of soil require irrigation more often. Mature citrus trees can go about 10 days between deep irrigations. Potted trees need to be checked daily.
TWO – Plant some flowers near a vegetable patch to attract beneficial insects. Coreopsis, cosmos, goldenrod, marigolds, sunflowers, and yarrow work well for attracting most beneficials. Lady bugs especially enjoy dill, golden marguerite, coriander, and Queen Anne's lace.
THREE – Mophead Hydrangeas(those with the big, round blooms) produce flowers on the previous year's growth – the “old wood.” To shape and control the size of a mature plant (5 years or more) and to avoid cutting off next year's flower buds, prune stems back to 12 inches right after the blooms fade. Fewer, but larger flowers will grow next spring if you cut some of the stems back to the base of the plant.
FOUR – Lawn turning brown? In large areas, it could be an irrigation problem. A quick irrigation auditof the lawn area will help determine if the sprinklers are matched and working properly. Information on checking the output of lawn sprinklers can be found here. Check with your local water provider to see if they are offering partial or complete rebates for changes to efficient sprinklers. In spots with a more defined edge, it could mean a lawn disease or pest problem. Evidence of caterpillars or grubs can be found just under the surface of the green grass right outside of the damaged area. If the brown area is not spreading, treatment to destroy the pests is unnecessary since it will not bring back dead spots and the pest is probably gone. If pest problems persist, investigate what cultural changes could be made to reduce susceptibility in the future.
ONE – Take some time during these dog days of summer to enjoy the landscape and garden while planning a winter garden and deciding on landscape additions. Select seed, gather whatever soil amendments, tools, and irrigation supplies are needed, and find where that perfect plant, shrub, or tree can be purchased.
TWO – Beets, carrots, turnips, and fast-maturing potatoes planted now should yield a crop by Christmas. Beet varieties that do well in our area are those with 60 days or less from seed sowing to maturity (as listed on the seed packet). Carrot lovers might try growing white, yellow, orange-red, or purple varieties from seed. Lee Miller's article, Planning and Planting a Cool Season Vegetable Garden, in the2013 summer issue of the newsletter, provides additional information. Lettuce, kale, and Chinese cabbage planted now will mature for fall salads. Try some heirloom lettuces this year to brighten both gardens and salads.
THREE – Amend soil with compost and soil conditioner before planting. Worm castings, though expensive, are worth the price. Choose pure castings or a mix of castings and compost. Now is also a good time to start a worm bin to provide castings for spring soil amending. Information on worm composting can be found here.
FOUR - Canes of single-crop blackberries and raspberries that have finished fruiting should be cut to the ground. Thin out the new growth. Remove all but 5 to 8 of the strongest blackberry canes and 8 to 12 strong raspberry canes per plant. Wait until after the fall harvest to prune ever-bearing varieties.
ONE – Although it seems kind of early to think about spring, now is the time to plant spring blooming bulbs. Bulbs should appear in nurseries right after Labor Day. They are most effective in big flowerpots and in kidney-shaped drifts at the front of garden beds. Some excellent choices include bluebells, daffodils, hyacinth, grape hyacinth, and tulips. Bulbs should bloom beautifully in spring with just rainwater over the fall and winter months.
TWO – Fertilize lawnsto thicken top growth, crowd out weeds, and strengthen grass roots for winter. Combination lawn fertilizers are a good choice. They contain a small amount of fast-release nitrogen for quick greening, and a larger portion of slow-release nitrogen. By using a mulching mower which chops the grass blades into fine pieces and leaves grass clippings on the lawn to decompose and release nitrogen into the turf, one or more lawn feedings per year can be eliminated.
THREE – Set out transplants of campanula, candytuft, catmint, coreopsis, delphinium, dianthus, foxglove, penstemon, phlox, salvia, hollyhock, and yarrow. Replace or plant new shrubs and groundcover, or, plant a tree on the southwest side of the house where it will provide welcome shade during the summer months. Use a deciduous tree for summer shade and winter sun. Chinese hackberry, Chinese pistache, gingko, Japanese pagoda tree, “Raywood” ash, and red oak can be good choices depending on the space available. Note the mature size of the tree before you purchase it to be sure there is ample room for it to grow into the beautiful specimen you expect. Plants send out roots in fall and winter while nature does most of the watering for you. Plants will be well established by the time new growth starts in spring.
FOUR – In case rain is sparse this year, organic mulch applied several inches thick around plants will help keep roots moist. Keep the mulch 3-5 inches from the trunks of plants to avoid problems with rot.
Information for this article has been gathered from:
- Author: Kathy Schick, Master Gardener
Plant viruses are very tiny unliving particles. In the midst of our current pandemic of COVID19, more accurately SARS-CoV-2, most of us are aware that viruses are minute packets of RNA (or DNA) surrounded by a protein capsid, but what some of us may not know is that the first virus to be studied, named, and understood was a plant virus called Tobacco Mosaic.
Disease: Tobacco Mosaic Virus
In the 1890s Tobacco Mosaic caused major economic problems for tobacco growers, who often lost 80% of their affected crop and many biologists were encouraged to study it. Dutch plant pathologist, Adolph Mayer, who named this disease in 1879, was unable to culture the disease or identify the pathogen. In 1887, Crimean botanist Dmitri Ivanovski tried filtering tobacco mosaic disease from the sap, known by then to spread the disease to any tobacco leaf it touched. He could not find any pathogen particle filtered out and concluded that the fluid contained a toxin that caused Tobacco Mosaic. In 1898, Dutch microbiologist Beijerinck published this shocking new theory: the disease was caused by contagious poison liquid, which he called virus, from the Latin for liquid poison.
Although Foot-and-mouth disease of cattle, caused by a filterable agent was discovered the same year, 1898, and the agent for yellow fever in Cuba, was found to be filterable in 1901, researchers didn't consider the animal pathogens related to the plant virus. It wasn't until the mid-1930s that tobacco mosaic virus had been crystallized and x-rayed to show that it was a solid particle.
Your plants may have viruses if the leaves form mosaic patterns, turning yellow. It's best to know which virus, because many viruses are spread by insect vectors such as leaf hoppers or aphids (you can remove these right away with insecticidal soap); others by tools, so you need to bleach your pruning tools, gloves, and even hoses; and sadly, some are spread by pollen. There is no cure for plants already infected with a virus; you need to remove them and then sterilize your gloves and tools.
But just as we have developed vaccines for human viruses, botanists have developed virus resistant stock. Buy these at the nursery and enjoy a virus-free garden while we work to control this new human virus.
Weed: Invasive Privet
Pest: Citrus Whitefly
- Author: Lee Miller, Master Gardener
Perennial: Lily-of-the-valley (Convallaria majalis) is a plant of partial shade and thrives in warm summers. It grows from a bulb, but the seeds and rhizomes can cause it to spread far if conditions are favorable. It likes soils that are silty or sandy, and moderately alkaline, preferably with an ample amount of humus. It is widely grown for its small, bell shaped, scented white flowers and ground-covering abilities in shady locations. It has gained the Royal Horticultural Society's Award of Garden Merit. All parts of the plant are highly poisonous so beware if you have curious kids. If ingested, even in small amounts, the plant can cause abdominal pain, vomiting, reduced heart rate, blurred vision, drowsiness, and red skin rashes according to Wikipedia which lists the toxic chemicals contained in this plant. However, the plant is very fragrant and it has been used in bridal bouquets of the rich and famous. For more information see: https://en.wikipedia.org/wiki/Lily_of_the_valley
Vine: Blue passion flower or common passion flower (Passiflora caerulea). There are about 400 species of Passion vine; some are used for food and some for flowers only. The flowers are attractive and very unusual. Passion vine is the unique food source for Gulf Fritillary (Agraulis vanillae) butterfly larvae and it is a nice plant to have if you have room and love butterflies and bees. For more information on Gulf Fritillary in California see: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=30667, I planted two of them at my old homestead to shade a patio area for my wife's studio. I bought them in 4 inch pots moved them to 5 gallon pots and then planted them the following year. They covered the patio a year later and my wife ended up disliking this plant so do be careful where you plant this aggressive growing plant. In my new home my neighbor has several plants next door and I have to police my yard to remove seedlings that pop up although I have trained one plant to a small trellis since I enjoy the butterflies, bees and blossoms. I have to prune it frequently to keep it confined to a small trellis./span>
- Author: Melissa Berg
Unfortunately, the predominant grasses promoted by Scott's were brought from European locales with abundant annual rainfall. After World War II, the advent of the lawn mower and powerful chemical fertilizers truly brought residential turf to the masses. However, attempting to homogenize installation of the same grass seeds (Kentucky Blue and Bent grasses) across all locales required a massive influx of irrigation, fertilizers and potent weed killers.
A NASA funded report in 2005 demonstrated that over 50,000 acres of residential turf was actively being cultivated by homeowners in the United States alone. That same report included data from the Environmental Protection Agency (EPA) citing the annual water use, exclusive of rainfall, by the typical suburban lawn at 10,000 gallons.
It is not, therefore, surprising that more and more homeowners, municipalities, business owners and academic institutions continue to consider viable replacement(s)for their existing expanses of turf grass. California, in particular, has been active in promoting “water wise” landscaping in light of persistent drought conditions.
The first Model Water Efficient Landscape Ordinance (MWELO) was established in 1992 for new and renovated properties. The original focus was to limit landscape space larger than 2500 square feet to no more than 50% turf grass. In 2010, a revision was adopted to reduce water usage by 14%. (It was commonly thought that newer, more efficient sprinkler technology would allow users to maintain their existing landscape while using less water.) MWELO was again amended in 2017 to further reduce water usage.
Municipalities, Long Beach and Los Angeles for example, have offered rebate programs aimed at providing homeowners cash incentives to remove residential turf and replace it with water wise landscaping options (such as xeriscaping, native and drought resistant plants and rock or hardscape). Limited funding and mixed residential results have compromised widespread success rates for such programs.
It is no secret that white clover (Trifolium repens) varieties are already a regular addition to ornamental turf seed currently available at retail locations across the nation. Both Dutch and New Zealand white clover varieties stand up to most foot traffic when paired with grasses, are low growing, are hardy in USDA zones 3-13, and set nitrogen as a benefit to those grasses (thereby reducing fertilizer needs).
There are currently a few schools of thought circulating when it comes to utilizing clover as a turf alternative. The first is whether or not the intent is to over-seed, i.e., leaving all or part of the existing turf in place and simply using micro-clover to cover bald or problem spots (such as excessive weed or soil-based issues). The second is simply opting to establish a monoculture of either clover or micro-clover after complete removal of the existing turf. A third concept uses a blend of multiple clovers in addition to low growing wildflowers (successfully in use by the city of Richmond, BC) to create an alternative urban setting that conserves all resources and reduces costs.
Unlike municipal or academic settings which often have more than one usage requirement for their turf sites (sport fields, parks and public access, etc.), the average suburban homeowner need only consider how and why they use or want to use their existing lawn. Is it merely ornamental or is the exterior living space in regular use by children, adults and pets?
Specific clover attributes to consider in the decision-making process include:
- micro-clover, unlike white clover, does not flower (for those with allergies).
- both clovers will grow to about six inches in height for a more pasture appearance but will tolerate mowing to three inches to encourage spread.
- both tend to successfully compete with most weeds found in lawns and tend to discourage insect pests.
- both are relatively deep rooted but neither does particularly well in heavy traffic areas.
- both do very well as niche growers between pavers or stepping stones.
- both tolerate compacted soils, and
- neither will yellow in response to pet urine.
While establishing a monoculture of clover or micro-clover would likely yield the greatest long-term benefits for a homeowner by eliminating mowing, reducing water consumption once established, attracting pollinators with white (or red) clover, improving soil and eliminating the need for fertilizer to name a few, it would require the complete removal of the existing lawn in order to properly prepare, seed and germinate clover either in the springtime or in late fall.
If, on the other hand, sites are well used by families, then over-seeding with clover could help reduce fertilizer needs and improve soil conditions. Either way households should realize a varying degree of reduced costs from water consumption, chemical application (whether fertilizer or weed abatement), labor costs (i.e., gardeners) and reduced time and maintenance investments.
The clover blend developed for use in British Columbia consists of Microclover (Trifolium repens var. Pipolina), White Dutch Clover (Trifolium repens), Sheep Fescue (Festuca ovina), Western Yarrow (Achillea millefolium), Baby Blue Eyes (Nemophila menziesii), Sweet Alyssum (Lobularia maritima), English Daisy (Bellis perennis), Roman Chamomile (Anthemis nobilis) and Perennial Ryegrass (Lolium perenne). To date, both installations of pasture setting at five-inch height and manicured cover at three inch height have been a resounding resource and investment success.
Despite its overwhelming benefits, white clover does have a few drawbacks. It is, in fact, drought tolerant, but will not thrive and spread when consistently denied water in hot conditions. This may cause some degree of aesthetic concern for homeowners, if, during the first season after sowing, insufficient seed has been installed and results in sparse growth. Installing in late fall often takes advantage of the wet season in order to sufficiently germinate seed however it can result in seed migration if water ponds at any point in the yard. Careful monitoring of the site and over-seeding will cure this problem and result in a thicker spring growth. As it is naturally invasive, defined parameters of containment are often required. It will grow, but not flower, in some shady locations and, most important, broadleaf herbicides will kill the clover if applied.
In a era where homeowners have become increasingly pressed for time and resources, sowing additional clover as a symbiotic supplement to turf, utilizing replacement clover blends to fashion a suburban pasture or establishing a monoculture of clover all appear to be promising options which provide suburbanites with viable alternatives for their exterior yard space; each according to their individual outdoor needs and functional desires.