It's springtime, and many of us are adding new plants to our gardens.  That means it is also a good time to review the principles of creating defensible space around our homes.

Fire is a normal part of the natural environment in California, so if you live in the wildland-urban interface (WUI), it's not so much a question of if, but of when your home will be exposed to wildfire.  With this thought and the devastation of the Camp Fire and other recent Northern California fires in mind, many Butte County property owners may be thinking about creating a fire-resistant landscape around their homes.  Not only is this a prudent course of action, a 2005 revision of the California Public Resources Code (PRC 4291) requires that property owners create 100 feet (or to the property line) of defensible space around homes and buildings.  Defensible space is defined as the area around a structure where the landscape is designed and maintained to decrease fire danger.  Creating defensible space also gives firefighters an opportunity to safely protect your home. 

The key to establishing defensible space is to utilize plants that are fire resistant and judiciously space them both horizontally and vertically. Increasing the space between plants limits the ability of fire to spread.  As a rule of thumb, Cal Fire recommends that on flat ground the space from the edge of one shrub to the edge of the next be twice the height of the shrub.  For example, if shrubs are two feet tall, they should be spaced four feet apart.  If the shrubs are growing on a moderate slope the space between them should be four times the height of the shrub.  The space between trees should be 10 feet from canopy to canopy and increase to 20 feet on a moderate slope.

If a fire reaches the crown of a tree, its heat intensity increases and this can increase the combustibility of surrounding vegetation.  Low tree branches create fuel ladders that allow fires to climb into a tree.  To prevent fires from ‘crowning,' these ladder fuels must be eliminated.  Cal Fire recommends that the lower branches of a mature tree should be pruned to create a clearance of three times the height of the shrubs beneath it.  For example if a shrub is four feet tall, the tree should be pruned so that there is 12 feet of clearance between the top of the shrub and the lowest branches of the tree.  For younger trees, the lower one-third of branches should be removed.

The area that is 30 feet closest to a home is often called the “home defense zone” or, as Cal Fire puts it, the “Lean, Clean and Green Zone.”  In this area, highly flammable fuels should be eliminated or minimized and widely spaced plants should be kept green and well irrigated.  Vegetation in this zone should be comprised of shorter plants such as grasses and non-woody flowers.  If shrubs or trees are planted, they should be fire-resistant plants such as deciduous trees (which shed their leaves in the fall) or non-woody natives and other perennials such as salvias.  Fire-resistant ground covers are also an acceptable choice for this area.  Avoid planting broadleaf evergreens (like holly and coyote bush), conifers (like pines, junipers, cedars, and firs) and palms, because they are highly flammable. 

Applying mulch is a good strategy for conserving soil water, reducing weeds and preventing erosion.  Normally, materials such as wood chips, shredded bark, leaves or straw are used as mulches because these organic materials have the added benefit of enriching the soil and improving its water-holding capacity.  However, organic materials burn, so within the five feet closest to a home, it is recommended that non-combustible mulches of rock, gravel, pavers or broken concrete be used instead of traditional organic materials.

When planning a firewise landscape, the contribution of hardscape features should not be overlooked.  Decomposed granite, cement, asphalt or gravel pathways and driveways make effective firebreaks.  Structures such as patios and masonry walls and water features like pools, ponds, and streams will also impede the advance of a fire. 

Before moving beyond the 30-foot home defense zone, mention should be made of items that do not belong too close to a home.  Most propane tanks should be located a minimum of 10 feet from any structure, and woodpiles should be at least 30 feet away.  A cord of seasoned firewood contains the energy equivalent of approximately 174 gallons of gasoline!  Would you store that much gasoline on your porch?  Also, flammable liquids such as gasoline, paint thinner, and turpentine should be properly stored away from ignition sources and combustibles.

The outer 70 feet of the defensible space is called the “reduced fuel zone.”  As with the home defense zone, plants in this zone should be well spaced horizontally and separated vertically to eliminate fire ladders.   Fire resistant plants should also be used here.  Most surface litter such as leaves, pine needles, and twigs should be removed so that this layer is no more than three inches deep.  Dead annual grasses should be mowed to a height of no more than four inches.  Mature trees without shrubs growing beneath them should be limbed to a height of six feet above the ground.  All plants should receive adequate water and dead branches in trees and shrubs should be regularly removed.  As noted in the UC Cooperative Extension's fact sheet on defensible space, “The goal of brush clearance is not to remove all vegetation.  When done well, cleared areas should still include enough well-spaced and judiciously pruned plants to protect against excessive erosion and provide wildlife habitat.”

If organic mulches are used in the reduced-fuel zone, a 2008 study showed that a mulch of composted wood chips spread two to three inches deep showed the slowest fire-spread rate of the eight mulches tested.  A potential disadvantage of wood chip mulches is that they tend to smolder and can be difficult to extinguish.  In general, fine, stringy mulches such as shredded bark burn more rapidly than larger chunks.

Establishing defensible space can be summarized by the following three R's:  1) Remove dead and dying plant material; 2) Reduce the density of vegetation and ladder fuels; 3) Replace hazardous vegetation with less flammable, well-irrigated fire resistant plants.

Further information on fire safety for homeowners can be found on the Cal Fire website at Home - Ready for Wildfire.  And for property owners who are considering landscaping from scratch, the Sonoma-Marin Saving Water Partnership has developed eight fire-rebuild landscape design plans that are well worth considering (Water Smart Landscape Design Templates - Sonoma- Marin Saving Water Partnership).

For more information on creating fire resistant landscapes, attend our Firewise Gardening workshop on May 2, part of the Master Gardeners' 2024 Spring Workshop Series. For information about all the workshops, and to register, visit our website.  All workshops are free, but registration is required.

Why not buy some plants for your fire-resistant landscape at the Master Gardeners' Plant Sale on Saturday, May 18, 2024? The sale will be held at our Demonstration Garden at Patrick Ranch, 10381 Midway, between Chico and Durham, from 9 am till noon. For more information, and a partial list of plants, see our Plant Sale webpage.  

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

Our rainy spring weather has been great for our gardens – but may also have encouraged some unwelcome garden visitors, including snails and slugs.

Snails and slugs are similar in structure and biology, but snails have a characteristic spiral shell while slugs lack a shell.  They both chew irregular holes on a variety of plants, preferring to feed on succulent plant parts such as leaves and flowers as well as seedlings.  These pests will also feed on fruits that are close to the ground.  Snails and slugs require a moist habitat, so they are most active at night or on cloudy or foggy days.  They are also hermaphroditic, meaning every individual has the potential to mate and lay eggs.  Thus, slugs and snails have the potential for rapid population growth when conditions are right.

To control snails, slugs and other pests, the University of California recommends that homeowners follow the Integrated Pest Management (IPM) process.  IPM is a strategy that focuses on long-term prevention of pests by utilizing cultural, biological, mechanical and physical controls.  With IPM, pesticides (chemical control) are used only as a last resort, and when pesticides are used, they are applied in ways that minimize harm to nontarget organisms, humans, pets, and the environment.

Cultural controls involve manipulating the environment to make an area less hospitable for a pest.  In the case of snails and slugs, a good first step is to eliminate places they can hide during the day.  Such hiding places include boards, stones, debris, weedy areas around tree trunks, leafy branches close to the ground and dense ground covers.  If hiding places can't be eliminated, vegetable gardens and susceptible plants should be located as far from them as possible.  Switching from sprinklers or flood irrigation to drip irrigation will also make the habitat less desirable for snails and slugs by reducing the humidity and moist surfaces they prefer.

Plant selection can also be a form of cultural control.  The seedlings of most plants and several plant species are particularly susceptible to snail or slug damage.  These include basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds, strawberries and many other vegetables.  By selecting plants that are more resistant to snails and slugs, a less attractive habitat can be created.  Plants that are resistant to these pests include begonia, California poppy, fuchsia, geranium, impatiens, lantana and nasturtium.  Many plants with stiff leaves or highly scented foliage such as lavender, rosemary, and sage also seem to be unattractive to snails and slugs.  In addition, most ornamental grasses and woody plants are unlikely to suffer serious damage from these pests. 

Mechanical or physical controls kill a pest directly or block a pest from an area experiencing damage. In the case of snails and slugs, handpicking is an effective mechanical control if it is done on a regular basis.  They can be searched out after dark with a flashlight and then either crushed in place or picked up with rubber gloves.  Once they have been picked up, they can be placed in a bag and thrown away in the trash, or placed in a bucket of soapy water and disposed of in a compost pile after they are dead. Alternatively, if you are lucky enough to know someone with pet turtles, you can give your snails and slugs to them (as long as they are healthy) -- most turtle owners are happy to receive these pests, which add protein to the turtle diet.  Those with backyard chickens may be similarly appreciative, as chickens, too, eat snails.

Another method of mechanical control is trapping.  Traps don't have to be elaborate.  Boards, flower pots and even melon rinds scattered throughout the garden will attract snails and slugs and then it is just a matter of scraping off the accumulated pests and destroying them every day or so, using the methods described above. Do not use salt to kill slugs and snails because is harmful to the soil.  Another type of trap consists of a can or jar buried in the ground and baited with beer or a sugar-water yeast mixture. Because the liquid in these traps must be replenished every few days, and will only attract slugs and snails from an area within a few feet, they are not considered to be particularly effective.

Copper flashing or copper foil can be used as a physical barrier for slugs and snails.  It is believed that copper is an effective barrier because it reacts with the slime of these pests, causing a disruption in their nervous system that is similar to an electric shock.  These barriers should be at least four inches wide with the bottom buried in the soil to prevent slugs from crawling under them.  Dry ashes or other abrasives such as diatomaceous earth can also be used as barriers for slugs and snails.  Such abrasives should be piled about one inch high and 3 inches wide to be effective.  However, these materials lose their deterrent value if they become damp, making them not very useful in most garden situations.  Another drawback of wood ashes is that they are quite alkaline and can have a detrimental effect on soil pH.

Biological control involves using natural enemies to control pest populations.  Snails and slugs have many natural enemies, but these beneficials are rarely effective enough to provide satisfactory control in the garden.  Domestic fowl such as chickens, ducks, or geese can be effective snail predators, but will also eat seedlings and should be employed with this in mind. 

Slug and snail baits can be applied as a last resort, but are most effective if used in conjunction with the IPM methods described above.  There are other effective baits, but baits containing iron phosphate are the only ones that are safe for children, domestic animals, birds, fish and other wildlife.  Iron phosphate baits are sold under many trade names including Sluggo and Escar-Go.  The bait should be placed in moist areas that snails or slugs are likely to frequent.  Timing is also important.  If the weather is very hot, dry, or cold, baiting will have a limited effectiveness because slugs and snails are least active during these times.  Take advantage of snail and slug habits by irrigating before baiting and scattering the bait in the late afternoon or evening. 

For more information on dealing with the various pests that plague your garden and home, attend the workshop on Integrated Pest Management (IPM) May 17, at the Demonstration Garden at Patrick Ranch.  This workshop is part of the Master Gardeners' 2024 Spring Workshop Series. For information about all the workshops, and to register, visit our website.  All workshops are free, but registration is required.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

It's that time of the year again – Ant Season!

We often experience ants in our homes when weather conditions change.  They are typically looking for food, water, warmth, and/or protection from extreme weather conditions. Ants belong to the insect order Hymenoptera and are close relatives of bees and wasps. The most common outdoor ant found in California is the Argentine worker ant. The Argentine worker ant is approximately 3mm long, dark colored and does not sting. They have no natural enemies. Their colonies have multiple queens and only the queens lay eggs.  An ant's life cycle moves from egg to larva to pupa to adult. Their nests are normally found in moist soils, under debris or along sidewalks and driveways. Argentine ants are drawn to sweet foods but will also feed on protein (e.g. dead bugs). The Argentine ant will venture up to 100 feet away from the nest to find food, water and shelter inside buildings.  Once inside, if ants find food, they will continue to invade until the food source is removed and/or the entryway sealed.

While it is not realistic to eradicate all ants from your backyard, you can effectively reduce the number of ants entering your home by following a 3-Step integrated approach as follows:

Minor Indoor Problem (small trail of ants observed infrequently). Prevent further intrusion by:

1)  Identifying the location where the ants are getting into the house. Inspect baseboards, floors, electrical outlets, vents, pipes, drains and walls for any entryways and seal them off (caulk is good for this). Destroy any nesting sites found close to the house.  Cut back trees, shrubs or wooded material touching the house and clear away mulch or debris that is next to the house.    

2)  Clean up food and water sources in the home. All sources of “attractive” food should be removed or securely sealed. Use soapy water to kill ants and eliminate their trails. 

Moderate (trails of hundreds of ants) and Severe (several hundred to thousands of ants continue to invade for weeks or months). Supplement steps 1 and 2 above with the addition of bait stations as follows:

3)  Install bait dispensers around the outside of the house (UC Researchers have had success using bait dispensers such as KM AntPro Liquid Bait Dispenser). Baits are more effective and less toxic than traditional pesticide treatments for ants. Baits are insecticides mixed with materials that attract worker ants.  The advantage of a bait station over an insecticide spray is that the spray only kills the worker ant while the bait station allows worker ants to take the bait back to the colony to feed and kill the colony ants, including the queen ant. When all the queens die, the colony is destroyed. Continue to refill dispensers regularly with liquid borate-based bait until the ant problem ceases. It is critical that you select the right bait/attractant for Argentine ants (liquid baits with 1% or less borate are suggested). Install at least one dispenser on each side of the house, next to structures where ants are trailing (but at least 5 ft. from any nest). Keep ant bait stations out of direct sunlight.

Following the 3-step approach above should correct home ant invasions.  For more information see the UC IPM Pest Note on Ants.

For more information on dealing with the various pests that plague your home and garden, attend the workshop on Integrated Pest Management (IPM) May 17, at the Demonstration Garden at Patrick Ranch.  This workshop is part of the Master Gardeners' 2024 Spring Workshop Series. For information about all the workshops, and to register, visit our website. All workshops are free, but registration is required.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

Looking for a drought tolerant plant?  Euphorbias are one of the most dramatic garden plants, and they happen to do well in our ongoing conditions of drought.  The genus is expansive and includes 2000 species of herbaceous perennials, annuals and biennials, as well as evergreen and deciduous shrubs.  You might think you are unfamiliar with this plant family, but one tender (and colorful) variety of euphorbia is customarily purchased during the holiday season: the Poinsettia.  The poinsettia's red leaves surround a “flower” called a cyathium, which is really a structure that consists of fused bracts that form a cup around the (actual) tiny flowers.

Euphorbias originated in southwestern Asia, Europe, Australia and the Mediterranean.  They are un-thirsty plants which prefer well-drained soil, and can be grown in either full sun or partial shade.  Euphorbias are not fussy about soil type either; they are tolerant of normal, clay, neutral or acidic soil.  And they are easy to maintain:  give them a little water to get established, but thereafter allow the soil to dry out between thorough waterings.

Euphorbia characias is perhaps the most commonly seen euphorbia in our area. The upright stems of this Mediterranean native are crowded with narrow blue-green leaves that form a dome-shaped bush four feet high & wide. Chartreuse or lime green flowers in dense, round to cylindrical clusters appear in late winter and early spring.  Characias is very drought resistant and thrives in part to full sun.

There are many Euphorbia varieties, crosses, and sub-species.  Below are a few interesting ones that do well here:

Classified as an Evergreen Spurge, the sub-species “Tasmanian Tiger” grows three feet wide and high with bow-tie like flower bracts edged in white.  The conical flower heads appear in spring.  Prune spent flower heads and stems down to the base of the plant—new ones will form during the summer.  This euphorbia provides interest all four seasons in our mild climate.

Euphorbia “Polychroma” is another showy variety that looks especially lovely alongside spring-blooming tulips and other bulbs.  It is also known as cushion spurge. Its bright golden flowers sit atop cushion-shaped light green leaves.  This versatile plant is useful in edgings, rock gardens and containers.  And autumn brings an extra treat:  red foliage color.  Trim this plant back hard to four inches in early summer to maintain a bushy, compact size. 

Euphorbia “Ascot Rainbow” matures at 20 inches wide by 20 inches high.  The edges of its narrow, gray-green leaves are edged in yellow, and it has variegated cream, lime and green flower bracts.  In cooler months, the foliage at the ends of stems can take on a rosy hue.  This more compact plant is attractive in groupings.

If your garden is plagued by deer and rabbits, they will avoid euphorbias because the stems of these plants contain milky white sap that can be an irritant to the skin or toxic if ingested.  For this reason, it is a good idea to handle euphorbias with gloves to avoid getting the sap on your skin or in your eyes. The sap has a latex base, so it is also good practice to clean your pruners after using them on euphorbias, to help maintain a sharp blade.

Euphorbias make unusually attractive cut flowers that can be incorporated in floral arrangements.  To prevent the sap from bleeding, dip the stems in boiling water or seal the stems by holding a flame to them for a few seconds before adding them to an arrangement.

The Master Gardeners' 2024 Spring Workshop Series has begun! There are still 13 workshops to come, on a variety of topics between now and May 22. For information about the workshops, and to register, visit our website.  All workshops are free, but registration is required.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.