- Posted by: Yvonne Rasmussen
We have all watched fruit trees grow and change through the seasons.
Fruit and nut trees grow most rapidly in the spring and summer months. As summer progresses, the growth rate slows until it all but stops in the fall. Days shorten, temperatures drop and the trees drop their leaves. Finally, the trees go dormant for winter.
It might not look like much is happening outdoors during the next few cold months of dormancy, but fruit and nut trees' hormonal systems are hard at work.
The longer, cooler days trigger hormonal growth inhibitors. Trees produce these hormones to prevent them from growing in winter and being damaged by cold. During its dormancy, if a tree has not received sufficient chill hours, even a warm spell with perfect conditions will not awaken it. Some plants do not have this hormonal protection. Many of us have lost plants that were fooled by an early warm spell and coaxed to bud, only to be killed by a later frost or freeze.
Napa County is luckier than many parts of the country. Winters are warm enough here that plants are not usually killed by extreme cold, yet we have enough chilling hours to meet the needs of our fruit trees and promote an abundant crop.
Trees have different requirements for the number of hours they need to break dormancy. Almonds require at least 250 to 500 hours at less than 45 degrees Fahrenheit to break dormancy. Pears, including Bartlett and Bosc types, need 700 to 800 chilling hours. Asian pears, which do well in my garden, need only 350 to 400 hours.
Most red-skinned apples need a cool climate to develop good color. But while some apple varieties require 500 to 1,000 hours of chilling, others need only 400 to 600 hours. When you shop for apples and other bare-root fruit trees, look at the plant tag to see if your choice has high or low chilling needs. Local nurseries tend to choose varieties suited to our climate, so you will usually find choices that are going to be successful. This is a good reason to buy locally instead of from catalogs that carry plants suited to zones and growing conditions different than ours.
We certainly have enough winter chill to grow many kinds of peaches, pears, plums and other fruits and nuts. Take a stroll down the bare-root aisle of your local nursery or home improvement store next month and survey the selection. Just be sure to read the plant tags and ask a nursery professional if you are not sure whether a variety is suited to your microclimate.
If your garden does not get much frost, you probably won't have much luck with sour cherries, which need 1,200 hours of chill. But you still have many options. Figs of all types, Hachiya and Fuyu persimmons, almonds, olives, pomegranates, chestnuts and pecans usually produce abundant crops with a minimum of chill.
A mild winter may be pleasant, but it can diminish our future harvests. Warm winters can result in delayed foliation and prolonged blossoming, but the buds deteriorate or drop, yielding few flowers or fruit.
December and January are the most important months for meeting chilling requirements. If the temperature falls below 45 degrees Fahrenheit for at least 400 hours in each of these months, and those cold hours are fairly evenly distributed, most of our orchard trees' needs will be met.
Once a fruit tree has accumulated the chilling hours it needs, a period of warm weather will signal to its hormones that it is spring, time to break dormancy and safe to grow.
Napa County Master Gardeners (cenapa.ucdavis.edu) answer gardening questions Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221.
- Author: Yvonne Rasmussen
Both walnuts and almonds were commercial crops in Napa County until grapes took over. In fact the Hartley walnut, now the most widely planted variety in the state, was developed in Napa County.
Pistachios, pecans and chestnuts are also appropriate trees for Napa County, although they have never been grown here commercially. All of them make nice shade trees, and if you can beat the squirrels to the crop, you can harvest some nuts as well. These nuts mature at slightly different times but have similar harvesting and storing requirements. Chestnuts require some different treatment for harvesting and hulling and don't require drying.
Walnuts ripen from early September through early November. They are considered ripe when the hull (also called the husk) darkens and becomes loose.
Pecans mature from late September through November and are considered ripe when the outer husk splits open and the shell within is completely brown.
Almonds ripen from early August through late September. They are ready to harvest when the hulls split and expose the shell with the nut inside.
Pistachios ripen from late August to early September and are mature when the hull changes from green to red and you can easily remove the nut from the shell.
Chestnuts are ripe when they fall to the ground. The nuts on a chestnut tree don't ripen evenly, so do not knock them off to harvest them.
For other nuts, you can use a pole or rubber mallet to knock the crop from the trees. Wear head and eye protection to prevent injury, and spread tarps under the trees to keep the nuts clean and prevent contamination from soil fungus. Collect fallen nuts promptly to
Remove the hulls soon after harvest to prevent spoilage and nut darkening. Use metal hardware cloth with a half-inch mesh, available at hardware stores. Rubbing the hulls against the mesh will help break them off. To make the job even easier, mount the mesh screen on a wood frame. Wear rubber gloves to protect your hands when hulling walnuts. The hulls contain chemical compounds called phenols that can stain hands and irritate skin.prevent insect and animal damage.
For chestnuts, which have a spiny husk, you will need heavy leather gloves.
All nuts except for chestnuts need to be dried if you intend to store them. If you fail to dry them sufficiently, they may develop mold and turn rancid quickly.
To dry nuts, spread them in a single layer on trays or screens in a shady or partially shady location with good air circulation. Cover them with netting or an additional screen to foil birds. Stir the nuts daily and cover them completely if rain threatens.
Crack open a few nuts every few days to check for dryness. The kernels inside should be crisp, not rubbery. In late summer and fall, drying may take only three to four days. Pecans should be dried more slowly to prevent the hull from cracking. A drying temperature between 75 degrees and 85 degrees Fahrenheit is best.
Properly dried nuts, shelled or unshelled, can be stored for up to a year at 32 to 45 degrees F. A typical home refrigerator is between 38 to 45 degrees. Most home freezers are around 32 degrees. Chestnuts still in their shells will keep only about a month in the refrigerator.
For more detailed information, consult the following publication: “Harvesting and Storing Your Home Orchard's Nut Crop: Almonds, Walnuts, Pecans, Pistachios and Chestnuts” (UC ANR Publication No. 8005). You can download this document at no charge from anrcatalog.ucdavis.edu/ or get it from the Napa County Master Gardeners office.
Napa County Master Gardeners (cenapa.ucdavis.edu) answer gardening questions Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221, or toll-free at 877-279-3065.
- Author: Yvonne Rasmussen
Many gardeners think of winter gardens as desolate and bare. With some good plant choices, you can create a garden that is beautiful and colorful even in the dormant season.
Planting trees and shrubs with interesting shape, bark or decorative fruit in winter can create a colorful and structurally interesting cold-weather garden.
Trees that retain fruit into winter can also provide food for birds, beneficial insects and other wildlife. These creatures will provide you with some winter entertainment, too.
Some of my favorite trees with attractive fall and winter fruit include pomegranates (Punica granatum), persimmons(Diospyros ssp.) and crab apples (Malus ssp.). All of them do well in Napa County. Any pomegranates that split or fruit that is too high for me to reach stays on the tree for birds to enjoy all winter. Hanging from bare branches, the fruits look like Christmas ornaments.
California native shrubs with colorful winter berries that are good for birds and wreaths include toyon (Heteromeles arbutifolia), with its clusters of small red berries, and snowberry (Symphoricarpos albus) which has white berries. You might also consider the eastern coralberry (Symphoricarpus orbiculatus), with white or pink berries.
Another California native tree with decorative winter fruit is the Western redbud (Cersis occidentalis). The fruits make a wonderful rustling sound in the wind, adding yet more pleasure to the winter garden. This drought-tolerant tree stays small and is thus a good choice for small yards. It produces magenta flowers in early spring, magenta pods in summer and yellow to red foliage in fall.
Look to trees and shrubs with fascinating bark or trunk shapes to provide interest in your deciduous garden. Trees with weeping or twisted branches can add a lot of drama. Some trees can be trained into intriguing shapes, while others have been expressly developed for branches that weep or twist.
I recently saw an example of a twisted black locust (Robinia pseudoacacia) called 'Twisty Baby' with bright pink flowers. 'Twisty Baby' is Monrovia nursery's trademarked name for this cultivar. It is drought-tolerant like other locusts, but because it is a dwarf, only getting 8-10 feet tall it is suitable for a smaller garden .
Maples (Acer spp.), dogwoods (Cornus ssp.) and eucalyptus (Eucalyptus ssp.) come in varieties with many different bark colors and textures. Some dogwoods are not deciduous, so choose carefully. The dogwood fruit is also good for wildlife.
For white-barked trees, many people often think of white birch (Betula pendula) or alder (Alnus rhombifolia or Alnus rubra). But these trees need well-drained soil and ample water. In our heavy clay soils, they are often not long lived. A better choice would be crape myrtle (Lagerstroemia ssp.) or lemon eucalyptus (Eucalyptus citriodora).
Our native manzanitas (Archtostaphylos ssp.) are among my favorite red-barked shrubs with interesting forms. They come in many sizes, from low-growing ground covers to large shrubs that work as small trees. They produce clusters of small, urn-shaped flowers in late winter through spring. Later, these flowers yield small, apple-like fruits that birds enjoy.
Manzanitas need good drainage but will tolerate poor soils. Once established, they require little watering, as infrequently as once a month or less.
Closely related to manzanitas are two other good garden shrubs or small trees with similar water needs, red bark and unusual red fruits: Arbutus 'Marina' and Arbutus unedo, also known as the strawberry tree.
Many trees have bark with an interesting texture. I grew up with a Chinese elm (Ulmus parvifolia), which has bark that falls off to leave a mottled pattern or "puzzle bark" on the trunk. These trees are resistant to Dutch elm disease and have long, arching branches, making them lovely for a patio. On the other hand, they have small leaves and produce many small fruits that can be messy.
Another tree with so-called “puzzle bark” is the sycamore (Platunas ssp.). Both the American sycamore (Platunas occidentalis) and the California sycamore (P. racemosa) are useful, attractive and appropriate trees for Napa Valley.
Melaleuca (Melaleuca ssp.), Catalina ironwood (Lyonothamnus floribundus) and the paperbark maple (Acer griseus) are a few examples of trees with shredding or peeling bark. Melaleucas are native to Australia. They come in various shapes, sizes and flower colors. All are drought-tolerant and have interesting bark that peels off in papery layers. The smaller shrubby species are useful as screens. The flowers attract birds and bloom in a range of colors.
Catalina ironwood has reddish, scaly, shredding bark; narrow scalloped leaves; and showy clusters of creamy white flowers in early summer. It needs good drainage, so choose its location carefully or it will not thrive.
The paperbark maple has lovely red bark in winter, showy fruit in summer and bright red fall color.
Yvonne Rasmussen is a UC Master Gardener. UC Master Gardeners of Napa County (http://cenapa.ucdavis.edu) answer gardening questions Mondays, Wednesdays and Fridays, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 707-253-4143.
- Posted by: Yvonne Rasmussen
- Author: Jane Callier
There are two types of strawberries: day-neutral varieties, also called ever bearers, and short-day types.
Ever-bearing plants are not affected by day length and have their highest production from spring through fall. Short-day types produce from fall through early spring when days are shorter. In our area, ever bearers are generally considered synonymous with day neutrals.
Your strawberry plants will need at least eight hours of full sun each day to produce well. Strawberries grow best in loamy or sandy soils. Before planting, prepare the soil by incorporating two to three inches of compost or other organic matter to a depth of at least 12 inches. Organic matter improves nutrient availability as well as the soil's structure and water-holding capacity.
Dig in some balanced fertilizer as well. Strawberries may still need to be fed several times during the growing season. Poor vigor or light green leaves tell you that it's time to fertilize. Heavy clay soil hampers strawberry growth and vigor and encourages disease, but you can succeed with clay soil if it is well drained. If possible, plant strawberries in raised beds to improve soil drainage and aeration.
When planting, remove any dead leaves, spread the roots out in the planting hole, and firm the soil around the plant. The crown of the plant — the area between the roots and the leaf stems — should be even with or slightly above ground level. Water the transplants well. Strawberry plants have shallow roots and need to be kept moist during the growing season. Use drip irrigation to keep moisture away from the fruit, minimizing fruit rot. Strawberries don't compete well with weeds, so be a vigilant weeder to extend the life of your beds.
Think about your strawberry bed as a temporary structure. Relocate plants after three to five years to prevent buildup of soil-borne pathogens. Avoid planting them in areas where you have recently grown other members of the Solanaceae family, such as peppers, tomatoes, potatoes, eggplant and okra. They are all subject to the same soil-borne diseases.
Napa County Master Gardeners recently completed a year-long field trial of three markedly different strawberry varieties. We grew two day-neutral varieties, Albion and Quinault, and one short-day variety, Sequoia. Trial participants planted bare-root seedlings in January. Some gardeners planted in containers, which work well because of the plants' small root systems.
Following common practice, we removed runners the first year to strengthen the mother plants. Some gardeners also removed the first flush of blossoms and consequently harvested a meager amount of Sequoia berries, if any. Most of us used straw mulch to retain soil moisture and keep fruit off the ground, away from earwigs, sow bugs, snails and slugs.
Birds pecking at ripe fruit were among the most annoying pests; some gardeners used netting to control them.
Fruit production varied. The Sequoia plants produced some huge, sweet berries but finished production before hot weather began, leaving us with the impression that its growing season was too short.
The Quinault plants yielded smaller, very soft fruit that needed to be eaten almost immediately. A few growers complained about having to throw away so many Quinault berries because they were too soft.
Albion berries were by far the best producers, yielding large, sweet, conical fruit on upright stems. Currently, the Albion is one of the most popular strawberry varieties in California. It was developed at the UC Davis and introduced only a few years ago. Photo of some of our harvest of Albion strawberries grown at our demonstration garden.
Our group kept yield records through Oct. 31. However, several gardeners, as well as their children and grandchildren, succumbed to temptation and ate some of the juicy crop before it had a chance to be weighed.
Consequently, our results are not rigorously scientific.
Roughly speaking, Albion berries accounted for 67 percent of the total yield, Quinault berries 25 percent and Sequoia berries 8 percent. Most of the participants intend to keep their plants going for another year.
For more information on growing strawberries and strawberry pest information see the UC integrated Pest Management website http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/strawberries.html
Napa County Master Gardeners ( http://cenapa.ucdavis.edu) are available to answer gardening questions Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 253-4221.
- Posted by: Yvonne Rasmussen
- Author: Denise Seghesio Levine
October 12, 2012 5:27 pm • DENISE SEGHESIO LEVINE
This is your chance to find plants that are native to the county, and the diversity may surprise you.
This year, the Native Plant Society has more than 1,000 different varieties of plants for sale. Whether you are looking for winter color, drought tolerance, deer resistance or another manzanita for your collection, you will probably find suitable choices at Skyline Park this weekend.
So how to decide? Native Plant Society member Kendra Baumgartner, a plant pathologist with the UC Davis, has grown many natives in her garden and has several favorites.
Bumblebees and hummingbirds are attracted to the bright red blossoms of California fuchsia (Zauschneria californica). This plant produces abundant trumpet-shaped flowers, does well in full sun, spreads easily by roots and is very drought tolerant.
Another colorful, drought-resistant bumblebee favorite that performs well in sun is flannelbush (Fremontodendron californicum). Flannelbush has big, tropical-looking yellow flowers, and it matures into a small tree. At the Martha Walker Native Habitat Garden in Skyline Park, you can see what flannelbush and other native plants look like and how large they grow.
To attract wild and domestic honeybees, consider wild or California lilac (Ceanothus spp.), which flowers in white, purple or blue. For a drought-resistant ground cover in a spot with full sun, choose C. gloriosus porrectus or C. prostratus. Blue beauties like C. ‘Frosty Blue’ and C. ‘Dark Star’ reach six feet tall or more. If you have a large garden, consider C. ‘Ray Hartman,’ which grows up to 18 feet tall.
Looking for color in a shady spot? For red blossoms in full or partial shade, Kendra suggests spice bush (Calycanthus occidentalis). Spice bush needs more water than some natives, since its natural habitat is normally in riparian areas. In addition to its unique, dark red blossoms in spring, spice bush offers the benefit of its spicy fragrance, which the thick, dark green leaves release when brushed or crushed.
Blue-eyed grass (Sisyrinchium bellum) is an herbaceous plant, but it is called a grass because it has blade-shaped leaves that grow in tufts. It spreads by roots, does well in full to partial sun and is drought tolerant. The plant takes its name from its little blue flowers with bright yellow centers, which appear in spring and summer.
Deer grass (Muhlenbergia rigens) is a big bunch grass that grows up to two feet tall. It can be hacked to the ground in winter, and it appreciates regular trimming during the growing season to keep it from looking too wild. In Kendra’s garden, dragonflies perch on the upper leaves, while sparrows take shelter under the canopy of leaves that drape to the ground.
Snowberry (Symphoricarpus albus) is another riparian woodland shrub that matures into a low bush with pretty, delicate leaves and tiny pink flowers. Snowberry produces large white berries in winter, an important food source for birds.
The Native Plant Society has at least nine different manzanita varieties available, from Arctostaphyolos uva-ursi ‘Pt. Reyes,’ a ground cover that stays below two feet in height, to A. ‘Dr. Hurd,’ a manzanita that can grow 10 feet tall. Manzanita is a popular plant in Napa County, for good reason. It has beautiful bark in red, tan and brown and tiny pink or white bell-shaped flowers in spring.
If you have room for a medium to tall tree in full or partial sun, take a look at the blue oaks for sale (Quercus douglasii). Blue oaks have beautiful blue-gray leaves that they drop in winter to reveal draping branches that are a favorite perch for songbirds (and, as Kendra warns, for the Cooper’s hawks that eat them). Blue oaks are drought tolerant once established.
Studies show that fall-planted perennials develop more drought resistance. They get off to a good start in warm soil and then have all winter to develop a deep, strong root system. While most plants need to be watered diligently during their first growing season, fall-planted perennials typically need less water for less time than their spring-planted counterparts.
The California Native Plant Society, Napa Chapter, sale took place Saturday, October 13, 2012 and Sunday, October 14, 2012 from 10 a.m. to 4 p.m. both days. While you are at the sale, pick up some information about the California Native Plant Society. This organization is an excellent resource for information about plants in our area. Consider becoming a member so that you can learn through working with them. Getting to know the plants around us and understanding their natural habitat adds richness to our lives in Napa County.
