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.
Citrus trees are evergreen, not deciduous, and never go fully dormant. As a result, they cannot withstand extremely low temperatures as well as deciduous trees, which are better prepared to handle cold weather.
I thought I had followed good preventive measures for my own trees by covering them with tarps and watering them deeply before the first freeze, but they still suffered significant damage. With near perfect hindsight, I realize that I should also have strung the trees with lights of at least 15watts to provide a little warmth.
After a brief mourning period, it was time to move on. The old English proverb that “necessity is the mother of invention” came to mind as I surveyed the ripe fruit on the trees.
A quick Internet search revealed that citrus juice can be canned and the process is easy. I already had canning jars and lids, a water-bath canner and a juicer so I was ready to go. I sterilized the jars and lids, squeezed dozens of lemons and limes and then heated the juice to 190°F for five minutes. I poured the hot juice into the sterilized jars, sealed the jars with lids and bands and processed them in the boiling- water bath for 15 minutes. Now I have enough canned lemon and lime juice to get me through the coming year. If you want to juice your frost-compromised citrus, do it sooner rather than later as the damaged fruit will dry out over time.
Today, when I look at my citrus trees, my first reaction is to do something to help them recover. However, the wise gardener waits until the extent of the damage becomes apparent. Prune too soon and you may remove parts of the tree that could recover if left alone.
Pruning too early may also encourage new growth that is susceptible to cold weather. It is also best to delay watering and fertilizing until spring. Resist watering until new growth appears, and avoid fertilizing until you know the full extent of the damage and have pruned the dead parts. The pruned tree, being smaller, will not need as much fertilizer as before. For now, just kick back and wait until spring or even summer.
Wait to prune until trees show signs of new growth. Identify the branches damaged by frost. Branches that aren’t generating new leaves need to be removed. In some cases, the bark will have a different color than the rest of the tree, or even begin to fall away.
Make all pruning cuts into living wood. Clean pruning tools in a mixture of 10 percent bleach and 90 percent water to prevent spreading disease between trees. If you are pruning more than one citrus tree, clean the tools in between.
Wait to water until the soil has dried out and there is new leaf growth. With fewer leaves to evaporate the water, damaged trees are less thirsty.
When new growth appears in spring, begin fertilizing. Several light feedings are better than one heavy application. Choose a fertilizer formulated specifically for citrus trees. These products are high in the nitrogen and chelated iron that citrus trees need.Apply a two-inch-thick layer of mulch around each tree, extending the mulch beyond the drip line but keeping it at least six inches away from the trunk.
Spring begins on March 20, so I will have to ignore my freeze-damaged trees for a few months before I can pick up my pruning shears and get rid of the unsightly leaves, twigs and branches. Fortunately, now is the time to start seeds for late-spring planting so I won’t be without something to do.
Workshop: Join Napa County Master Gardeners for a workshop on “Rose Pruning” on Saturday, January 18, from 10 a.m. to noon, at the University of California Cooperative Extension (address below). January is the best time to prune your roses. Come learn pruning techniques from a certified Rosarian. Bring your rose questions. Online registration (credit card only)
Mail-in registration (cash or check only).
Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 11:00 a.m. until 1 p.m., except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( 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.
Raw kale salads with lemon and olive oil or with peanut and ginger dressing are making appearances on restaurant menus. Baked kale chips are a hit with kids. And more cooks than ever before are looking to kale for their winter vitamins.
Kale is a member of the large Brassica oleracea species. Cousins include collards, cauliflower, Brussels sprouts and broccoli. All are commonly referred to as cole crops, from the Latin word caulis, meaning stem or stalk.
Now is a great time to shop for kale seedlings at your local nursery or garden center. More varieties are being offered than ever before as interest and appreciation for this versatile vegetable grows.
Choices include Tuscan kale (also called lacinato, dinosaur kale or black palm) with its bumpy, black-green leaves; ‘Redbor,’ with its frilly purple-red leaves; and Siberian kale, with bright green, smooth leaves. All kales are rich sources of calcium, potassium and Vitamin C. History tells us that kales and wild cabbages have been foraged, cultivated and eaten throughout Europe for more than 3,000 years.
Tuscan kale adds a dramatic component to edible landscapes and is the preferred type for Italian cooking. Its leaves are up to ten inches long and two to three inches wide. As you harvest the leaves from the bottom, the plant gets taller and taller.
‘Redbor’ kale’s gorgeous magenta leaves make a stunning backdrop to orange winter calendulas. Try growing beautiful deep-pink flowering kales in front of a trellis of ‘Old Spice’ sweet peas.
If you prefer your vegetables to be green, consider Siberian kales, which are a little more like collards. ‘Winterbor’ is a deep frilled green and is both beautiful and useful in the kitchen.
Most kales are extremely winter hardy. While kales produce year round in our climate, the first light frost will bring out their sweetness as the leaf cells develop carbohydrates to buffer the plants from the cold. Harvest outer leaves from the bottom up; avoid picking the inner leaves which protect the growing point. Territorial Seed Company recommends washing and then cooling your kale harvest quickly. Keep refrigerated in a plastic bag to maintain freshness.
Kale thrives in well-dug, humus-rich soil with neutral to slightly acidic pH. Cold weather does slow the action of soil microbes, so you might need to add a complete organic fertilizer and some bone meal to your beds when you plant winter crops, just to give the microbes a boost. Always read fertilizer labels and apply as directed.
Vegetables in this family are occasionally subject to aphids. Immediately after planting, cover your crops or seed bed with Reemay or other row cover cloth to keep aphids from getting a hold. If you do discover aphids, you can usually control them with a hard spray of water. Winter crops are not typically as prone to aphid infestations as spring and summer crops are.
If you see little moths fluttering above your kale or other cole crops, look closely for cabbage looper, the larva stage of these moths. Loopers and other worms can eat your crops from the bottom up. Call the Master Gardener Help Desk (see below) for help in identifying and solving the problem.
Baby kale leaves can be harvested as soon as 25 days after planting, although cold temperatures can slow germination. Toss the baby leaves into fresh salads. Larger leaves can be steamed, braised, grilled, used as wrappers, stuffed, roasted and added to soups and stews. Harvested young, tender kale leaves can add color, texture and extra nutrients to winter meals. Seed can be sown successively throughout most of our mild winter.
My daughters taught me their favorite summer camp salad: Wash and dry the kale leaves. Remove the large central rib, then tear the leaves into bite-size pieces or shred. Squeeze fresh lemon juice onto the leaves, and rub the juice into the leaves with your hands until the leaves are wilted and soft. Finish with a drizzle of good olive oil and salt to taste. For other ideas for preparing kale, check www.epicurious.com. The site has 176 recipes for kale.
Open garden: Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursday mornings, from 10:30 a.m. until noon, except the last Thursday of the month. Connolly Ranch is at 3141 Browns Valley Road at Thompson Avenue in Napa. Enter on Thompson Avenue.
Workshop: Join Napa County Master Gardeners for a workshop on “Indoor Gardening” on Saturday, November 9, from 9:30 a.m. to 11:30 a.m. Transform a room into a vibrant living space with houseplants. Learn how to use color, texture and pattern for design and how to care for houseplants. The workshop will be held at the Senior Multi-Use Center, 2185 Elliott Drive, American Canyon. Online registration (credit card only) Mail in registration (cash or check).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners ( 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.
If you can tackle “Supercalifragilisticexpialidocious,” a catchy tune from Disney’s Mary Poppins, it should be a piece of cake to learn scientific plant names.
I hear a few gardening friends groaning. I hear my mother reminding me to sound out long, tricky words syllable by syllable. Just sound them out.
Sometimes easier said than done, but there is good reason for having scientific names. First, common names can misguide us. A bluebonnet in Texas is a lupine in California, and a jasmine in California is a pikake in Hawaii. Common names may work fine locally, but try to explain a local flower to gardeners in other parts of the world.
Also, when we have a sick plant in our garden, we have to know its correct name before we can solve its dilemma.
This is why gardeners look to scientific or botanical names. Botanical names are the same the world around and their meanings convey information we need to choose the right plants for our gardens.
During the 1700s, plant explorers collected many largely unknown plants from around the world, a quest that continues today. Carl Linnaeus, a Swedish botanist of that era, spent his life categorizing and naming plants. Using Latin, a universal language of the time, he developed the binomial naming system. This method gives every plant two names, the genus (generic name) and the specific epithet (species). The species name is often descriptive of the genus.
He grouped these names into families of related plants. Just as we recognize similarities in our own families, like blue eyes or curly hair, Linnaeus used plant similarities and origins to classify his findings.
Before Linnaeus’s system, a single plant might be saddled with many long Latin names that only a few interested scientists understood. The binomial system may seem daunting at first because many plant names are long tongue-twisters, but the information provided makes it worth mastering the code.
Pronouncing the Latin name correctly is important if you are describing a plant to someone else. If you pronounce the name incorrectly, you are conveying wrong information. The 2013 edition of Sunset’s Western Garden Book offers four pages on plant pronunciation and why we use botanical names. The “New Pronouncing Dictionary of Plant Names” (American Nurseryman Publishing Company) is a useful pamphlet that fits neatly in a pocket.
The binomial system groups plants into categories, from least specific (the family) to most specific (the variety).
Family is the large umbrella group. Family names are capitalized and end in aceae, such as Rosaceae, the family that includes roses.
Genus is the first word in a botanical name, and it is always capitalized. With Nandina domestica (heavenly bamboo), for example, Nandina is the genus.
The species is the second word in a botanical name. It often describes a plant characteristic such as color, size, shape, scent or origin. It is not capitalized. With this knowledge, you can deduce that Helleborus foetidus has a less than captivating scent.
Variety names are often descriptive, such as ‘Altissimo’ (tall), or they may indicate an officially registered, cultivated and named plant known as a cultivar (‘Bowles Mauve’). Varieties are enclosed by single quote marks.
Some species include many different varieties. If you want to buy a rosemary plant for cooking, look for Rosmarinus officinalis. Rosmarinus is the genus; Rosmarinus officinalis (meaning medicinal) is the species. You may find several named varieties at the nursery, such as ‘Tuscan Blue,’ ‘Spice Islands’ and ‘Blue Spires.’ Each one is slightly different, but all of them can be used in the kitchen.
Common names can be misleading, which is why we rely on Latin botanical names. For example, the fragrant star jasmine isn’t really a jasmine. Its botanical name is Trachelospermum jasminoides (meaning jasmine-like), and it is in the Oleaceae (olive) family. The common name for Choisya ternata, an evergreen shrub, is Mexican orange, but some call it mock orange. Philadelphus, a deciduous shrub in the Hydrangea family, is also commonly known as mock orange. Both shrubs have fragrant white blossoms.
There is much more to learn about plant names, but understanding the binomial system is a good start. Oh dear, my dog, Sofie, is eating my Philadelphus coronarius. She has good taste.
Workshop: Napa County Master Gardeners will lead a workshop on “Succulents in Your Garden” on Saturday, June 15, from 9:30 a.m. to 11:30 a.m. at Napa Valley College’s Upper Valley Campus, 1088 College Avenue, St. Helena. Learn what succulents will grow best in our climate and how to utilize them in your garden design. Learn how to care for them and keep them looking good and free from pests and diseases.
Online registration (credit card only)
Mail in registration (cash or check only)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. Napa County Master Gardeners (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?