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What's Hot Archive 2019

What's Hot in January

dirt and burnt trees
by Barbara Hill

I’ve been hearing that soil can change during a wildfire, and actually repel water. Is this true? How does it happen?

It is true that with intense heating, soil can become water-repellant, or hydrophobic. In a hot wildfire, a waxy substance is created when plant material is burned. This substance penetrates the soil as a gas and solidifies as it cools, covering the particles with a waxy coating. This creates a layer that is generally up to one inch thick, but can be thicker. Plant roots and soil microorganisms help break down these hydrophobic strata, although thicker layers may persist for a year or more.

When the amount of water infiltrating the soil is reduced, it can lead to increased runoff, erosion, flooding, and lower water quality, as well as negatively impact plant growth. Find out ways to identify and treat hydrophobic soil (pdf).

What's Hot in February

forced blooms
by Barbara Hill

What is force flowering, and how do I do it?

Force flowering the branches of deciduous, blooming trees and shrubs is an easy way to bring the color and fragrance of springtime into one’s home. By bringing cut stems into the warmth and light, you’re tricking them into thinking it’s spring. You can force-bloom quince, spirea, forsythia, redbud, pussy willow, dogwood, spicebush, and serviceberry. Cuttings from fruit and nut trees, such as apples, peaches, cherries, plums, and almonds, can be successfully forced as well. Select branches with a large number of buds, being careful to remove only those that preserve the plant’s shape and structure. Cut at an angle, and immediately place in water. Place indoors in bright but indirect light, and change the water every three to four days. A show of blooms should appear in two to four weeks.

What's Hot in March

peach blossoms
by Barbara Hill

I keep seeing “chill hours” listed on fruit and nut tree tags. What are they, and why are they important?

Like Goldilocks and her porridge, trees don’t want the weather to be too cold when, after a long winter’s nap, they produce new, tender buds – but they don’t want to wait until it’s too hot, either, because they’ll miss out on a full season of growth and fruiting. How does a tree know when it’s “just right” to resume growth?

Trees produce hormones in the fall which stop growth processes and initiate a state of rest. Even though dormant trees appear to be asleep, fruiting trees and shrubs are still paying attention, and keeping track of the temperature – specifically, chilling (roughly, temperatures between 32F and 45F degrees, also known as winter chill or vernalization). Growth inhibiting hormones will keep the trees safely in dormancy until a certain amount of winter chill has been accrued. This prevents them from being fooled into growth during spring-like midwinter warm spells and, when the right number of chill hours has been reached, signals that it’s the optimal time to break winter dormancy.

Chill requirements can vary widely, depending upon the tree type and variety. In general, a tree’s chilling requirement should come close to the amount of winter chill normally received in the area where it’s planted. If varieties with higher requirements are grown in milder climates, too little chilling will mean that blooming and leaf regrowth may be delayed, and fruit set will be poor. Conversely, if a tree with a low chill requirement is grown in colder climes, it will break dormancy too soon and suffer late-winter freeze damage.

Fortunately for Butte County gardeners, most of Northern California receives between 800 and 1500 hours of chilling each winter. This means that most commercially available fruit and nut trees will find our climate “just right.”

For more information:
The California Backyard Orchard: Tree Selection

What's Hot in April

fruit  before and after thinning
by Barbara Hill

Fruit thinning seems wasteful to me – I want more fruit, not less! Do I really need to do it?

Although it may seem counterintuitive, you and your fruit trees will both benefit by early spring thinning. Removing those tiny apples and plums now will result in a big payoff at harvest time, since fruit provided with plenty of elbow room will be larger and more flavorful, and less vulnerable to disease. Unburdening those limbs is an investment in future harvests, too, as trees overtaxed by an excess of fruit may be more prone to sun damage and disease, and overladen branches are susceptible to breakage. Plus, by consistently leaving too much fruit on the tree, we run the risk of eventually enduring years with next to no harvest at all: unthinned trees may become alternate bearing, a "feast or famine"-type cycle in which a tree produces excessively one year, and little the next.

Learn more about fruit thinning.

What's Hot in May

stages of tick development
by Barbara Hill

Recent articles about Lyme disease have me concerned, but since I’m not a hiker, I don’t have to worry, right?

The good news is, tick-borne diseases are rare, and following a few simple, preventative measures will greatly reduce your chance of exposure. These little pests can be found in lots of places, however, so gardeners, picnickers, and even those with indoor/outdoor animal companions should join their wilderness-loving neighbors in tick awareness.

Once hatched, ticks have three life cycles, all of them parasitic. Mature ticks climb grasses or shrubs to seek hosts, while immature larvae and nymphs—essentially, tiny versions of the adults—hang out in leaf litter and on branches, logs, and tree trunks. But don’t fret—you can relax and enjoy your al fresco exploits by:

  • Regularly inspecting clothing or exposed skin, and doing a full body check at the end of the day.
  • Wearing long-sleeved tops tucked into full-length pants, which are in turn tucked into socks.
  • Applying repellents or acaricides (a pesticide that kills mites and ticks) to skin or clothing.
  • Using veterinarian-recommended collars and/or topical or oral products that kill and repel ticks on dogs and cats.

Learn more about this topic at Lyme Disease in California and Prevent Lyme Disease.

What's Hot in June

by Barbara Hill

What can I do this summer to improve the soil and keep weeds out of my unplanted vegetable garden beds?

An excellent way to suppress weeds and enrich soil is to grow a summer cover crop. Buckwheat is a popular choice, as it grows in a wide variety of soils, germinates quickly, and creates a dense, weed-squelching canopy in just a few weeks. The fine roots improve tillage, and its profusion of white flowers will attract pollinators, parasitoids, and other beneficial insects to your garden. Cut, mow, and till back into the soil before seeds set. Buckwheat’s tender stalks and roots decompose quickly; in two to three weeks, your bed will be ready for another crop. In our climate, several plantings can be grown in a single summer. Photo by Alex Stone.

For more information, see:
Buckwheat as a cover crop
Overview of cover crops

What's Hot in July

by Barbara Hill

My coast redwoods have always looked sickly, so I’m having them taken out. Can you suggest a replacement that would do well in Butte County?

As you’ve discovered, even though coast redwoods can sometimes be found in Central Valley stores, they only thrive in the moist, humid climate of the Northern California coast. Fortunately, there are plenty of tough, drought-tolerant conifers that are well-suited for our hot, dry summers. An excellent alternative would be a deodar cedar (Cedrus deodara), a majestic conifer that resembles the coast redwood, but requires much less water. Photo by Lazaregagnidze.

For more information: 
Cedrus deodara
Drought Tolerant Conifers

What's Hot in August

compost bin
by Barbara Hill

Is it okay to add weeds to my compost pile?

Compost, sometimes referred to as “black gold”, is treasured by gardeners for the opulent benefits it imparts to our soil. Composting can be as simple as piling up waste and letting nature take it from there. Called cool or cold composting, the primary requirement for this method is patience, as it will take a year or two before the materials are sufficiently broken down to be garden-ready. Unfortunately, any weed seeds that may have found their way into the pile will be garden-ready, too. The hot method produces compost much more quickly, and most pests, pathogens, and weed seeds won’t survive if the pile stays hot enough, long enough: the toughest seeds require exposure to temps of one hundred forty-five degrees for thirty days or more. Maintaining the proper balance of air, moisture, carbon, and nitrogen is key, as is periodic turning. To avoid growing a bumper crop of bindweed, the surest way to keep that black gold untarnished is to just toss seedy weeds into the green barrel.

For more information, see UCANR’s article Weed-free Compost.

What's Hot in September

by Barbara Hill

When is the best time to divide my irises?

When irises, as well as perennials such as coreopsis, daylilies, penstemon, lamb’s ears, scabiosa, and yarrow become crowded or overgrown, they can be reinvigorated by providing them with a bit of elbow room. Not only does this practice keep plants healthy and looking their best, it’s an inexpensive way to add more of your favorite specimens to the garden. Dividing plants in autumn’s cooler temperatures protects them from heat stress, and gives them plenty of time to get established before cold weather arrives. Before taking spade to soil, give perennials a modest shearing. If the soil is dry, water thoroughly a few days prior to digging. Crammed-together irises can be pulled or broken apart by hand, and good-sized plants can be sectioned into multiple clumps. Select the healthiest rhizomes or rooted segments to place in pots or replant directly into the ground.

For how-to’s, see UCANR’s article Dividing Garden Perennials.

What's Hot in October

leaffooted bugs (Leptoglussus)
by Barbara Hill

I found these weird bugs all over my tomatoes! What are they?

Your tomatoes are providing a feast for leaffooted bugs (Leptoglussus), a large cousin of the stinkbug named for the distinctive leaflike structures found on the adults’ rear legs. At maturity, they may reach one inch in length, with long piercing/sucking mouthparts they use to suck plant juices from leaves, shoots, and fruit. They will feed upon a wide variety of plants, and in serious infestations of agricultural crops such as almonds, pistachios, pomegranates, and citrus, a large proportion of the harvest may be lost.

Happily for the home gardener, leaffooted bugs rarely appear in sufficient numbers to cause more than minor cosmetic damage, although their predation may cause immature tomatoes to abort. Adults and smaller nymphs are often found clustered together, making identification and physical removal relatively easy. Brush bugs into a bucket of soapy water, or knock them to the ground and crush them. Check the undersides of leaves for their barrel-shaped eggs, and destroy any you find. If further outbreaks occur, a combination of control methods is recommended, including application of Insecticidal soap; removal of weed hosts and overwintering sites; and use of physical barriers such as row covers. To protect bees and other beneficials, insecticides should only be used as a last resort.

Learn more about leaffooted bugs

Photo by siamesepuppy

What's Hot in November

by Barbara Hill

How can I tell when my olives are ready to be picked and cured?

Harvest times vary depending upon the olive variety, region, and overall weather conditions. In California, the first phase of picking generally begins in mid-September when fruits have reached the “green-ripe” stage. These olives have attained their mature size, are an even yellow-green in color, and release a creamy-white liquid when crushed. As the ripening process continues, the green hue changes to a mottled reddish-brown, and in December, final harvests gather the fully ripe “naturally black” olives.

Green olives tend to be more dense, firm, and bitter than black olives, but the texture and flavor of any olive depends upon the method and length of the curing process. A quick nibble of a just-picked fruit will make abundantly clear why curing is necessary. Oleuropein, a bitter compound found in the skin, may be effective at repelling pests, but millennia ago, clever humans developed a variety of methods to leach away the offending substance, with delicious results. Processing with lye is the fastest way to accomplish this, but care must be used with this highly caustic substance. Oil-, water-, brine-, and dry-curing techniques are slower but safer, and all are excellent methods for the home gardener.

For more information see UC ANR’s publication Olives: Safe Methods for Home Pickling (pdf).

What's Hot in December

bareroot tree
by Jeanette Alosi

What is a bare-root fruit tree?

Fruit trees can be planted any time of year while bare-root fruit trees are only available during the winter months when trees are dormant (December through March). They are called bare-root trees because after growing for 1 to 3 years in a wholesale nursery they are dug up, and the soil is shaken from their roots. The roots of the trees must be kept moist by covering them with soil, sawdust or compost until they are planted. There are many advantages to purchasing a bare-root fruit tree. They are less expensive, easier to transport and handle, and grow more easily into native soils. For more information on how to plant a bare-root tree see our Real Dirt article on Planting Bare-Root Fruit Trees, and UC ANR’s publication on Planting and Care of Young Trees (pdf).

Photo provided by UCANR.