Last summer did your tomatoes look at you longingly as you passed by? Do your daffodils wilt when you are near? Were your giant sunflowers only one foot tall?

If so, maybe these plants were trying to tell you something. Your soil may require some help providing the structure and nutrients that plants need to thrive.

You can't just put your plants in dirt and expect them to flourish. Remember: there is a difference between soil and dirt. Dirt is what you get on your clothes and hands while working in the soil. Soil is made up of elements that have been decomposing since the earth was created.

Soil is composed of bedrock and mountain stones broken down over eons by wind and rain. Since Napa Valley is in a volcanically active area, much of our soil is made up of volcanic matter deposited by the river. In addition, plants, animals and bacteria contribute to the composition of our soils. We have heard a lot about how chemicals used in the garden do not break down in the soil but remain in our streams and rivers. Natural materials are a better choice.

Consider having your soil tested to see what minerals it contains, what minerals it lacks, and how much fertilizer you need. Online merchants sell bacteria and mycorrhizae (beneficial fungi) that can help restore life to your soil. Adding manure from cows, horses or other grain-eating animals will improve the soil, but be sure the manure has been aged to kill any weed seeds. Otherwise you can expect a major weed crop wherever you spread the manure.

I live on the valley floor, where the soil includes a lot of silt deposited by the Napa River during flooding. This silt, which is clay like, creates a hard layer on top of the soil when it dries. Where the river floods its banks, this layer can be two to three inches deep or more.  

Clay soils hold a lot of water but don't provide much opportunity for plants to grow. The soil particles are tiny. For comparison, if a clay particle were the size of a penny, then a particle of sand would be the size of a house. The area between soil particles is where air and water reside, and plants need both to grow. Plants in soggy soil often die of root rot.

One of the easiest ways to improve clay soil is to add compost and other organic matter. Compost is composed of organic matter that has broken-down to form humus. It has little nutrient value but it does aerate the soil and improve drainage. In contrast, worm compost (vermicompost)—the castings produced by worms that eat food scraps and other organic matter—is a nutrient-rich soil amendment. Earthworms happily munch on kitchen scraps, lawn clippings, newspaper, even cardboard.

If you would like to learn more about composting, attend one of the nine composting workshops that will be conducted this year by Napa County Master Gardeners in conjunction with partnering agencies. One workshop is entirely devoted to worm composting, and the workshop on April 12 will be conducted in Spanish. Register  online at www.cityofnapa.org/compost. You can help your soil produce the healthiest plants in town. To learn more about the soil food web, I recommend the book Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web by Jeff Lowenfels and Wayne Lewis.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

Workshops: Napa County Master Gardeners will conduct a workshop on “Warm-Season Veggies” on Saturday, March 15, from 9:30 am to 11:30 am, at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Prepare now for your most successful vegetable garden ever.  Learn what to plant from seed, how to choose transplants, and when to plant for a bountiful harvest from spring into fall. Online registration (credit card only)
Mail in registration (cash or check only)

Napa County Master Gardeners will conduct a workshop on “The Small Home Vineyard” on Saturday, March 29, from 9:30 am to 11:30 am, and from 12:30 pm to 2:30 pm. at the Yountville Community Center, 6516 Washington Street, Yountville. The morning session will focus on bud break to harvest. Learn the basics of managing a small vineyard including grape physiology, canopy management, vine nutrition, fertilization, irrigation and cover crop.  The afternoon session will focus on identifying and managing the most common vineyard pests, especially powdery mildew. To register,call the Parks & Recreation Department at 707-944-8712 or visit its web site.

Napa County Master Gardeners welcome the public to visit their demonstration garden at Connolly Ranch on Thursdays, from 10:00 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.

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.

 

My previous column about indoor gardening addressed the importance of choosing houseplants wisely and learning about each plant’s requirements for light, water and temperature. I also urged you to be an active indoor gardener, moving plants around to accommodate shifting lightover the seasons, and to monitor your plants’ water needs closely. Your attentions will be rewarded with vigorous, healthy houseplants.

This column addresses the role of humidity and ventilation, proper feeding and pest control. For more advice, consult the University of California’s California Garden Web site (http://cagardenweb.ucanr.edu/Houseplants/), gardening books at a local library, or the staff at nurseries with a large houseplant selection. Consider investing in a comprehensive indoor gardening guide to help you learn about the plants in your care.

Most houseplants are native to tropical areas, where conditions are warm and humid. To increase the humidity easily, place pebble trays under houseplant containers. As the moisture around the pebbles evaporates, relative humidity increases. Grouping plants also helps a bit. Surprisingly, misting the leaves does not affect humidity much, although I find that some tropical plants with large leaves seem to benefit.Other plants will rot if spritzed with water, so be sure you understand each plant’s needs.

When feeding houseplants, follow package directions to the letter. More is not better.Excess fertilizer can kill a plant.

Houseplants need nitrogen (N), phosphorus (P) and potassium (K) as well as very small amounts of other minerals, called micronutrients. Most fertilizers contain a blend of nutrients in varying proportions. Foliage plants need more nitrogen, while flowering plants need more phosphorus.

Fertilizers come in several forms, from liquid to granules to sticks. Although roots take up the most nutrients, leaves can also absorb them. However, ordinary fertilizers will scorch foliage, so be sure to select a foliar fertilizer if you intend to treat the leaves.

Common houseplant pests include aphids, fungus gnats and spider mites. There are many types of aphids, and they can increase at an alarming rate. They feed by sucking plant sap. Infestations typically appear on soft, young growing shoots and around flower buds. If you catch them early,you can vanquish aphids by pinching off affected shoots or gently washing off the aphids with tepid water. You can also spray aphids with insecticidal soap, which smothers them. After spraying, wipe them away.

Fungus gnats are tiny, dark gray flies that flit about on top of the soil. The larvae feed on rotting vegetation in the soil. Plants growing in severely infested soil appear weak, grow poorly and often lose older leaves.

To combat fungus gnats, allow the soil to dry out between each watering. Use sticky yellow traps to catch adults. Alternatively, repot the plant in fresh soil. If these measures fail and the plant is large and worth saving, you can drench the soil with Bacillus thuringiensis(Bt),a safe and effective organic pesticide.

Spider mites are probably the most dreaded houseplant pest. They pierce the leaves and suck out plant juices.They hide on the underside of leaves and may go unnoticed until the plant is seriously infected. Affected leaves may show numerous yellow pinpricks, or they may be dry and limp although still green. If uncontrolled, spider mites can kill one plant and then move on to others.

Dry conditions encourage spider mites. Keep plants humid by placing them on beds of pebbles. If only some parts of the plant are infested, clip off those parts and dispose of them in a sealed plastic bag. Treat the remainder of the plant with insecticidal soap at least twice at five-day intervals. Pesticides often do not provide controlas spider mites rapidly become resistant to them.

In an upcoming column, I’ll discuss common houseplant diseases, soil needs, repotting and propagation. In the meantime, bring your houseplant questions to the Napa County Master Gardener Help Desk (address and hours below).

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.

 

Many gardeners have the same questions about caring for indoor plants. Why do the tips of the leaves turn brown? What’s the right amount of water? Why doesn’t my plant bloom? What’s that stuff on top of the soil, or crusted around the pot? Can I grow succulents indoors?

Indoor gardeners face many of the same issues as outdoor gardeners. They must choose their houseplants wisely and understand each plant’s requirements for light, water, temperature, humidity, soil and fertilizer. What’s more, indoor gardeners have to be actively involved in plant care.

Palms and spider plants, for example, benefit from bright light and even some direct sun. Succulents and cacti require fast-draining soil and infrequent watering, while the umbrella plant needs frequent watering to thrive indoors. Orchids placed in the sun will scorch. African violets prefer filtered light and even some fluorescent light in winter. The active indoor gardener takes time to learn about each plant’s ideal growing conditions.

The staff at local nurseries should be able to advise you about the houseplants you select. You may also want to purchase a comprehensive indoor-gardening guide to read more about the plants in your care. The University of California’s California Garden Web site (http://cagardenweb.ucanr.edu/houseplants/) can answer many questions.

Houseplants need light to manufacture their food through photosynthesis. Most foliage houseplants are evergreen and native to tropical or subtropical climates. In their natural habitat, they typically live under a canopy of taller vegetation, receiving plenty of indirect bright light but no full sun. In our homes, however, walls and roofs diminish the amount of light and create dark corners with little bright light.

In addition, the angle of light changes seasonally. Some areas of your home may experience direct light in winter, while summer’s sun is too high to enter the room. The amount of light in a room can vary dramatically. Take time to study the available light in your home and notice how it changes over time. Light duration, intensity and quality all have an impact on indoor plants.

As for water, plants need it for many chemical processes. They take it up by their roots and distribute it via a network of water-conducting tissues. Alas, water—too little or too much—contributes to many plant problems. The houseplant novice has the same question as the outdoor gardener: How often should I water my plants?

Two key rules govern houseplant watering: Never permit the soil to dry out completely, and never allow plants to stand in water for an extended time. Roots may die in either situation. As a general rule, a plant in a pot six inches or less in diameter needs water when the top inch of soil is dry. For plants in larger pots, wait to water until the top two inches are dry. Use your index finger to check for moisture. If the soil feels damp, do not water.

Ordinary tap water is usually fine for indoor plants. However, if your water is artificially softened, do not use it on houseplants.  

Brown leaf tips may be an indication of inconsistent watering. Use a calendar or other reminder to track your watering schedule. Cacti and succulents do not need water as frequently as umbrella plants. Watering every houseplant every Saturday earns you points for consistency but may not be a good practice.  

Providing a comfortable temperature is also essential to your houseplants’ health. Most indoor plants tolerate normal indoor temperature fluctuations. Foliage plants grow best between 70°F and 80°F during the day and between 60°F and 68°F at night. Indoor flowering plants, such as bulbs, miniature cyclamen, African violet and primrose, prefer the same daytime temperatures as foliage plants but lower nighttime temperatures, 55°F to 60°F. These lower evening temperatures promote recovery from moisture loss, intensify flower color and prolong flower life. 

Avoid exposing houseplants to wide temperature fluctuations or to extremely high or low temperatures. These conditions may cause plant decline, evidenced by a spindly appearance, damaged foliage or flower drop. Be an active indoor gardener and move plants from windowsills and doorways when the temperature spikes or plummets.

In future columns, we’ll explore other houseplant requirements—for humidity and ventilation, fertilizer, soil, repotting, propagation and pest control. In the meantime, bring your houseplant questions or concerns to the Napa County Master Gardener help desk (address and hours below), or e-mail us your questions using the diagnosis form on our website.

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.

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.

 

 

 

I remember ending last month’s to-do list with a promise that December’s garden to-do list would be shorter. What was I thinking?

There is actually a lot to do in the garden in December. If you planned ahead and were industrious in late summer, you are probably harvesting Brussels sprouts, cabbages, broccoli, kohlrabi and kales. Harvest individual Brussels sprouts from the bottom, or cut off the entire stalk and store somewhere cold while you use them. We have two upright, full stalks of bright green Brussels sprouts resting in our cool pantry, and I pop off a potful of sprouts as needed.  

Beets, carrots, scallions, radishes and lettuces of all varieties are easy to grow in fall and winter. Micro-greens and Asian greens also thrive in cool and even cold weather. It is easy to fill your salad bowl from the garden at this time of year.

When the weather gets really cold and my lettuce freezes, I have found that if I do not touch the leaves until they thaw, they will often be fine. Touching them damages fragile cells, which causes the leaves to deteriorate when they thaw in the morning sun.

Carrots and radishes can be sown now, as can English peas, sugar peas, sweet peas and spinach. Perhaps you are harvesting some of these crops now if you planted them in late summer. Pomegranates seemed to ripen a little early this year, but you might have a few of those left to pick, too. Complete your olive harvest if you haven’t already. University of California Extension has instructions for curing olives in several ways.

You can plant fava beans now. They are a popular cover crop in Napa Valley, preventing erosion during the winter rains. Plowed into the soil in spring, they contribute nitrogen and biomass, replenishing fertility.  

However, if you grow fava beans for the table, wait to harvest them until the beans swell inside the fuzzy green pods.  After shelling them, you can eat the beans raw or cooked, peeled or unpeeled. Italians enjoy young fava beans peeled and raw, with olive oil and salt for dipping, crusty bread and a glass of red wine. You can also let the pods mature on the plant and harvest the dry beans to use for soup.  

If you plant radishes right now, you may have some fast-growing varieties ready by Christmas or New Year’s. Consider crisp red ‘Cherry Belles’ or long white daikon types. Smooth- or curly-leaf spinach varieties, chard, parsley, and sets of shallots and garlic can still go in.  

Because a gardener’s work is never done, you will already find transplants at the nursery for spring harvests of broccoli, cabbage, cauliflower, lettuce and arugula. Shop for rhubarb and artichokes early; nurseries offer them on a first-come, first-served basis. When the supply runs out, you won’t see them again for a year.

Nurseries may still have a few bulbs for spring bloom. Their blossoms are lovely in the garden, but consider forcing bulbs for indoor color, too. Many bulbs are sold with directions for forcing. Some instructions may recommend chilling bulbs before planting outdoors. Follow the directions and enjoy the results.

Get out your floating row covers to extend the harvest of some crops as the temperature drops. You can also use this material to keep aphids and other insect pests off broccoli and cauliflower. If you have done your winter garden cleanup and eliminated piles of debris, lumber, pots and other hiding places for snails and slugs, you won’t find many pests. If you are still finding a lot of slugs, you might need to tidy up the garden a bit more.

December brings more gray days, but it is still possible to have lots of garden color in protected spots and in pots and baskets. If blue or purple flowers cheer you, then head for the pansies and violas. Violas in yellows and oranges make a wonderful contrast in sunny baskets.  

Remember to stay off your garden soil when it is wet to avoid compacting it. If you expect to plant bare-root roses, fruit trees or vines this winter, try to get the planting holes dug before heavy rains begin. Lay plastic sheeting over the planting holes to prevent them from getting too wet to work.

Begin pruning your deciduous fruit, nut and shade trees now. Do not prune evergreen shrubs, roses or vines. Pruning evergreens stimulates new growth that could be vulnerable to a cold snap. Cover your compost pile when it rains so you do not drown your hard-working microbes. Bundle up and enjoy our Napa Valley winter. January’s to-do list will surely be shorter.

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.

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.