Chilly nights challenge our citrus trees, succulents and other frost-tenderlandscape plants. On top of the seissues, holiday commitments take up a lot of the time that one might otherwise spend in the garden.
So what should a gardener be doing this month?Some tasks are priorities, so let's tackle those first. If you have citrus trees or other tender plants, you must mitigate their exposure to frost or they will suffer. Already I have recorded night-time temperatures below 30°F at my home.
I have five citrus trees in four locations, so I use a combination of strategies. For the two trees close enough to the house to reach with an outdoor extension cord, I have strung Christmas lights (not LED type) in the branches. I plug in the lights on cold nights. Another tree, a dwarf citrus, is short enough that an old patio umbrella clears its branches. I toss an old comforter over the umbrella ribs when frost threatens. For the other two citrus, I set up ladders to support tarps and old blankets. Once the temperature begins to rise in the morning, I remove all the coverings and unplug the lights. Unless we get an arctic blast, all of these trees should survive the winter.
Water is also a priority. Until rains thoroughly wet the soil, I pay attention to my rain gauge. If we have less than an inch of rain in a two-week period, I figure that any actively growing plants will need irrigation. In my garden, that's mostly vegetables. My fall-planted greens are producing lots of leaves for stir-fry and salad, and November garlic is beginning to emerge.
Citrus trees will also need some water, especially if the weather is cold. During the summer I used gray water from my laundry to water my roses; now that those plants are going dormant, I'm using the gray water for citrus trees. I have switched to a plant-friendly laundry detergent and have not noticed any negative effect on the plants irrigated with gray water. But note that I only use gray water on trees and shrubs; the vegetables get potable water.
Already we have had enough rain in Napa Valley to start greening our hillsides. But the same rains have prompted weeds to emerge in my garden beds. While these weeds are small, they are easy to pull or hoe. Weeds take just as much water as edibles, so removing them now will conserve water for the plants I want.
As you weed, note areas of bare soil. If possible, cover bare spots with mulch or compost, or plant a cover crop if you can keep it moist. Winter is hard on soil. Rain compacts it; wind and sun dry it out. Soil is the foundation for all of your plants so protect it. Earthworms, fungi and other soil microorganisms will reward you with healthier soil next spring when it's time to plant.
Last but not least, finish your fall cleanup. Remove spent vegetable plants. Put diseased plant material in your yard-waste bin rather than in your compost pile. Most backyard compost piles do not get hot enough to destroy pathogens. In contrast, the waste-management companies compost at high temperatures that do control bacterial and fungal diseases. Rake up leaves and other litter to eliminate hiding places for snails, slugs and harmful insects.
In next week's column, we'll look at December gardening activities that are less like maintenance and more like fun. Although I have to admit, on sunny winter days I am perfectly happy to be outside even if all I do is pull weeds. It makes a nice break from working on the computer or in the house.
Workshop: U. C. Master Gardeners of Napa County will host a workshop on “Rose Pruning and Maintenance” on Saturday, January 9, from 10 a.m. to noon, at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa. This workshop will feature demonstrations of proper pruning techniques. Master Gardeners will discuss types of roses, common rose diseases and routine maintenance. On-line registration (credit card only);Mail-in registration (check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
One of my favorite houseplants at this time of year is holiday cactus. During November and December, these cacti are covered with long tubular blooms. Over the years, I have collected several plants, each with different colored blossoms, including white, pale pink, hot pink, red and salmon.
While I used to think that all of these plants were Christmas cacti, I recently learned that two types of holiday cacti bloom during November and December. The one that most stores sell is Schlumbergera truncate, the so-called Thanksgiving cactus that blooms around that holiday. The second type is Schlumbergerabridgesii, which blooms about one month later. That one is the true Christmas cactus.
The Thanksgiving cactus has flattened stem segments with saw tooth projections along the margins; the Christmas cactus has more rounded margins. In addition, the anthers of the Thanksgiving cactus are yellow, while the anthers on the Christmas cactus are purplish-brown.
These cacti are native to South America, growing in tropical jungles at altitudes ranging from 3,000 to 5,000 feet. They are epiphytes, meaning that they grow on objects or other plants. They obtain water and nutrients from the humid air around them instead of from the soil. When grown indoors, these cacti need bright but filtered light, so place them near a south-facing window. In warmer months, they can live outside in a sheltered shady place.
While these plants are easy to grow, it is sometimes a challenge to get them to bloom for the holidays. There are a few tricks to encouraging bloom.
Pinch back the stems in early June to encourage branching and more terminals for flowers. At the end of September, remove any end segments that are either damaged or less than a half-inch long. Flower buds will only form on undamaged, mature stem segments.
Holiday cacti set their flower buds when the days turn shorter and cooler. To create optimum blooming conditions, provide cool nighttime temperatures (50°F to 55°F) and 12 to 14 hours of darkness starting in mid-September. Street lights, car lights or indoor lighting can disrupt the required dark period, so place cacti where constant darkness is guaranteed. Reduce watering as growth slows. When flower buds appear, gradually increase watering and provide temperatures between 60°F and 65°F. Feed every other week during the bloom period with a fertilizer intended for houseplants.
While the plants are blooming, keep them away from drafty spots and heating or air conditioning vents. After blooming, the plants appreciate a rest period of six to eight weeks. Keep them cool (around 55°F) and water lightly until new spring growth appears. During the growing season,feed monthly with houseplant fertilizer diluted to half strength. Stop fertilizing in late summer to encourage fall flowering.
Holiday cacti like to be pot bound. Repot them about every three years in the spring. Choose a fast-draining mix containing 60 to 80 percent potting soil and 20 to 40 percent perlite. Allow the soil mixture to dry out partially before watering so air can circulate around the roots.
Propagate the cacti by taking cuttings in May or June. Select stems with three to five segments. Let cuttings dry in the shade for at least one day. Fill a clean four- to six-inch container with fresh potting soil. Insert three to five cuttings one inch deep into moistened soil.
Cover the plants and container with a clear plastic bag or other translucent material to create a mini greenhouse. Support the plastic so that it does not touch the cuttings. A clean, clear plastic soda bottle with the bottom removed works great as a covering. Place the covered container in bright, indirect light. In three to eight weeks, roots will form and you can remove the covering.
If your cactus isn't blooming by Christmas, all is not lost. Give it the daily darkness treatment for six to eight weeks, and you should have a flowering plant by early spring.
Workshop: U. C. Master Gardeners of Napa County will host a workshop on “Rose Pruning and Maintenance” on Saturday, January 9, from 10 a.m. to noon, at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa.This workshop will feature demonstrations of proper pruning techniques. Master Gardeners will discuss types of roses, common rose diseases and routine maintenance On-line registration (credit card only) coming soon. Mail-in registration (check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
The espalier technique was developed centuries ago in France. Gardeners there used rope to shape fruit trees and found that the trees produced a good crop. It seems that limbs trained horizontally produce more fruit than branches pointed up. However,the method does take more work and planning than an orchard layout.
Dwarf figs, apples, pears and citrus are the most common fruit trees grown as espalier. Other fruit trees are more difficult to train in this way.
You can espalier a tree against a wall unless you are in a very warm climate. In that case, the heat reflected by the wall might cause fruit and leaves to burn.
You will need to set up a trellis system on which the trees can grow. Be sure to leave enough space to move behind the trees so you can prune them easily. Then you need to install posts tall enough to support the mature trees. Seven to eight feet is suggested. Place the first wire about three feet above the ground and then one foot apart after that.
At the nursery, select trees with lots of branching. You are going to cut off most of the branches and direct the remainder along the trellis wire. If you can't find such a tree, start with a whip (a young, slender, non-branching trunk).Another alternative is to prune off all the trunk's branches and direct the new, flexible growth along the wires.
The espalier method is not something you do once to each tree and then you're done. Itis a process. It involves constant training and pruning to get branches growing in the right direction.
I suggest purchasing bare-root fruit trees because they are much less expensive than container trees.When you plant them for espalier, you use the same methods that apply to any bare-root tree. Site the trees close to the trelliswith at least six feet between each tree.
Dig a hole wide and deep enough to accommodate all the roots. You can prune some of the root tips off before planting.Create a mound inside the planting hole. Set the tree on the mound and spread the roots evenly around, then take a look. Make sure that when you back fill the planting hole, the tree is no deeper than it was before. Be sure the graft union (where the scion is grafted to the rootstock) is above the soil line.
Remove the tree and water the hole well. Then place the tree on the mound again and refill the hole with soil. Water again. You want the soil to go into all the nooks and crannies. Stomp on the soil to compact it.
Trim all branches that you cannot easily train to the wire. Tie branches to the wire with a plastic tie. Trim back the growing tip to buds coming out the sides at the next highest wire.
You will need to continue this training throughout the life of your fruit trees.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
‘Wonderful' is the pomegranate most of us pick up at the grocery store. Originally found in a bundle of cuttings from Florida, ‘Wonderful' has been propagated widely in California since the early 1900s. But the story of pomegranates (Punicagranatum) goes back much further.
Also called Chinese apples, pomegranates are one of the oldest documented edible fruits. They require long, hot summers and can survive under myriad conditions. For best fruit production in Napa Valley, plant pomegranates in a sunny location in ordinary soil with good drainage. For the first two years, water deeply every two to four weeks in dry weather to encourage root establishment and fruit production.
When pomegranate plants are about two feet high, select four or five of the healthiest-looking branches, preferably well-spaced, and cut them back to 12 inches.Remove the remaining growth and any shoots or suckers that appear above or below these chosen branches.
Pomegranate trees can be grown as dwarfs, but most reach 15 to 20 feet tall. Disciplined pruning can keep them tidy in smaller spaces.
The pomegranate produces fruit at the end of new growth. Judicious pruning annually for the first three years will produce bushy plants with abundant new growth each year.
With their shiny, dark leaves, bright orange flowers and dramatic red fruits, pomegranates make attractive, long-lived additions to the garden. Their ruby arils—the pulp-covered seeds—are beautiful in salads and make a refreshing juice. The fruit is also used commercially for making grenadine, the sweet red syrup in a Shirley Temple. Local birds appreciate any fruit left on the tree.
No wonder the Spanish missionaries considered pomegranates essential to propagate along El Camino Real in the 1700s. Pomegranates are still often found on old homesteads and in historic gardens across the state.
By 1927 California boasted 2,750 acres of pomegranates. As of 2011, the last year the USDA tracked commercial production, California had more than 30,000 acres of pomegranate orchards.
Some fruit trees, like plums, are susceptible to oak-root rot and can't be grown near diseased oak trees. Fortunately, pomegranates do not have this issue. Sometimes the pomegranate rind splits, exposing the seeds to insects, moisture and mold. Regular watering minimizes splitting, as it does for tomatoes and other fruits. Cease watering two to three weeks before your anticipated harvest.
Allow pomegranates to ripen fully on the tree as they won't ripen further after harvest. Clip the stem to avoid damaging the fruit; do not pull the fruit off the stem.
Pomegranates actually improve in storage, becoming juicier and more flavorful. Keep the fruit cool but not cold. A temperature below 41°Fwill turnred arils pale and promote decay. Stored at the proper temperature and around 85% humidity,the fruit can last for up to seven months. When the arilsstart to fade and look streaky, flavor fades, too, and it is time to put the fruit in the compost.
Pomegranate seeds germinate readily, but you may not get a high-quality tree from seed. Most pomegranates are propagated from rooted cuttings.
A few years ago, University of California Extension fruit-tree specialists Paul Vossen and Deborah Silver published a paper recommending pomegranate varieties for our area (http://home orchard.ucdavis.edu/plant_pomegranate.pdf). They describe ‘Wonderful' as producing large, deep-red fruits with juicy red arils, small seeds and good flavor. Vossen and Silver also suggest ‘Grenada' and ‘Eversweet' for a harvest that begins in August instead of September.
And if you have space for only one? Taste different varieties to find your favorite. The good news is that even ordinary pomegranates from your grocer's shelf can be Wonderful.
Workshop: U. C. Master Gardeners of Napa County will host a workshop on “Making Wreaths from Your Garden” on Sunday, December 6, from 2 p.m. to 4 p.m., at Yountville Community Center, 6516 Washington Street, Yountville. Learn what plants from your garden will make good wreaths and how to choose and prepare plant materials to make them last a long time. Get tips and tricks for designing and making easy creative wreaths for the holidays or any time. Each participant will create a wreath to take home, using locally collected plant materials and supplies provided. To register, call the Parks and Recreation Department at 707-944-8712 or visit its web site.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Monarch butterflies are declining rapidly in number, along with the native milkweed plants that they depend on from Canada through much of the U.S. Experts attribute the decline to the expansion of cities and suburbs,morelawn mowing, more herbicide use and more intensive farming practices. The drought hasn't helped.
California boasts 15 native species of milkweed; most are drought tolerant. These plants are the primary food of Monarch larvae.Milkweeds also support a large range of pollinators, such as bees and hummingbirds.
Milkweeds are named for their milky sap, a sticky latex that oozes out when the plant is cut. The plant tissues contain cardenolides, a type of steroid. Monarch caterpillars eat the plants, which then protects them by making them distasteful to predators.
Most livestock avoid milkweed unless they are very hungry or unless it is accidentally mixed in with hay or feed. Milkweed tastes bitter and all parts of the plant are considered toxic to most mammals. Use gloves or wash your hands after touching the plant and avoid touching your eyes.
Native Americans used fibers from the milkweed stem to weave cloth and make cords and ropes. They treated ringworm and bee stings with the sap and made an extract from the leaves for curing coughs, relieving lung inflammation and stimulating lymphatic drainage.
The seed pods contain a fair amount of floss that carries the seeds on the wind. Today the floss is used as a hypoallergenic filling for pillows and comforters.
Milkweeds typically flower between late spring and the end of summer. After they disperse their seed, the above-ground growth dies back, readying for winter. My milkweed had a little stub above ground throughout winter. This last spring and summer, it shot up to about three feet with good space between the narrow green leaves. In mid to late summer, the colorful blooms attracted one lonely Monarch that seemed to keep circling back to feed and rest over many days.
I adopted this plant without knowing what type of milkweed it was. I was told it was hardy and drought tolerant and to leave it alone after planting. I was instructed to water it for a few weeks and then very little once established.
Newly planted seedlings produce leaves the first year; in the second year, you get flowers. Once I saw the orange, red and yellow blooms, I looked up what kind of milkweed I had. To my horror, I learned that it was a tropical milkweed bloodflower (Asclepiascurassavica), also known as butterfly Asclepias ‘Bright Wings'.
This milkweed is not native north of Mexico. Unfortunately, due to its showy flowers, multiple bloom periods and ability to attract egg-laying Monarchs, it has been widely planted.
Scientists are concerned that this non-native milkweed, unlike North American milkweeds, will have foliage year-round when grown in areas with mild winters and adequate moisture. This persistent foliage might encourage Monarchs to lay eggs outside of their regular breeding season or to linger in areas longer than they normally would and to risk freezing. The year-round presence of milkweed is also associated with higher parasitism rates in Monarchs, lowering the survival rate.
My tropical milkweed has produced many seed pods. I remove them before they pop open to prevent reseeding. I recently tried finding some native milkweed in nurseries to replace mine, but they were sold out. Mail-order sources had milkweeds, but they looked too much like mine.
This spring I will plant seeds of showy milkweed (Asclepias speciosa, which grows up to five feet) and narrow-leaved milkweed (Asclepiasfascicularis, which reaches three feet) or get seedlings at the nursery. The California Native Plant Society recommends these species for Napa Valley.
My Monarch moved on by October 10. I was going to remove the tropical milkweed, but on close inspection, I noticed four healthy, good-sized Monarch caterpillars and a number of tiny ones chomping away. I hope some will make it to the coast as butterflies before winter. Then I will uproot the tropical milkweed.
For more information on native milkweeds and Monarch butterflies, consult the website of the Xerces Society for Invertebrate Conservation or the California Native Plant Society.
Workshop: U. C. Master Gardeners of Napa County will hold a workshop on “Fruit Tree Selection and Planting” on Sunday, November 15, from 2 p.m. to 4 p.m. at Yountville Community Center, 6516 Washington Street, Yountville. Get ready to plant bare-root fruit trees or to transplant from a pot into the ground. You will learn about soil types, site selection and preparation, and first-year care so that your new fruit trees thrive. The second half of this workshop will help you decide what trees to plant. Topics include disease resistance, rootstock influence, climate and chill hours, and specific varieties that perform well in various parts of Napa County. To register, call 707-944-8712 or visit the Parks and Recreation web site.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.