by Penny Pawl, U. C. Master Gardener

Swales are ditches or trenches that catch rainwater for the purpose of conserving it in the soil. And if you top the swale with compost, you will gradually improve the water-holding capacity of the soil underneath.

Most swales are created on hillsides to keep rainwater from washing downhill, but mine are on the Napa Valley floor. They are not straight but rather bend around the plants already in the area. They are about two feet wide and 12 to 15 inches deep. Compost was spread on top of the soil including inside the swale.

Last winter, rains filled the swales up three or four times. Each time, it took about three days for the water to be absorbed and stored under the swale. I have been planting a dry habitat garden in this area. Eventually, these drought-tolerant Mediterranean plants, which have been in the ground only one to two years, will be on their own, with no additional water.

Because my plants were young, I watered every few weeks this past summer. A slow-growing Hollywood juniper that had been in the ground for a long time, with no water, doubled in size this past  year. I can only presume it is because of the additional moisture provided by the swale.

As the roots of the plants go deeper and I continue to add compost on the surface, the water-holding capacity of this area should increase.

Last winter I placed a couple of garbage cans under downspouts, covering the cans between rains. I used this water on potted plants throughout the winter. Since then I have acquired two 300-gallon plastic containers. They rest on a raised platform under rain gutters, so after they fill, I can attach a hose and get some water pressure.

Because of the West’s growing water shortage, people are devising more ways to save rainwater. Some methods are elaborate, while others, like mine, are simple and inexpensive.

You can buy adapters to cut into gutters to direct the water and flat-sided tanks that butt up against the side of your house. These tanks are lidded and usually made of dark plastic so that light does not get inside. If kept covered, the water stays clean and free of mosquito larvae.

So how much rainwater can you glean from your roof? Most roofs are pitched, so a 1500-square-foot house may have a roof with double that surface area. In that example, an inch of rain will produce 1000 gallons.

To see how much rainwater you can save, check the chart at www.rainwater-green.com/RainfallCharts.pdf.  Driveways, parking lots and streets also displace rainwater. In our area, any water not retained likely ends up in the river and bay

Some states do not allow collection of rainwater. Others allow limited collection to protect the interest of those downstream. Cal

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By Yvonne Rasmussen, U. C. Master Gardner

At this time of year, I start to notice the ants in my garden, and sometimes in my house. In the garden I see them mostly when I water in an area that has been dry for awhile. They come boiling out from various places, frantically carrying their eggs and young out of the ground to keep them from drowning.

In the garden, ants are rarely a problem, but they can be an indication of other insect problems and sometimes a nuisance. I rarely see ants inside the house, but when I do, I know they must be going to a source of water or food.

I follow the trail until I find where they are going. If it is a food source, I clean it up, and within a day they are gone. If they are seeking water, not food, then it may be a bit more work to isolate the source and eliminate the ants. Next step is to finding where they are getting in and caulking or sealing the entryway.

There are more than 12,000 species of ants in the world and about 200 species in California, but the good news is that only about a dozen are considered important pests. The most common ant we see in our garden and home is the Argentine ant. These are small grayish-black to brown ants traveling in long trails to and from their food source.

They are attracted to sweet food sources most of the year—to protein in the spring—and they nest in shallow spots underground. By late summer, they can build up large colonies that may be connected and have multiple queens.

In Napa Valley, we also have pharaoh ants, house ants, thief ants, Southern fire ants, velvet tree ants, and carpenter ants. These different types can be identified by their size and color. Luckily we do not have the red imported fire ant that has been found in  Southern California. It is an aggressive stinging and biting ant.

If ants are causing you problems and you want to control them, management starts with proper identification. Once you know the type of ant and its behavior, you can plot effective control. Catch a few and throw them in the freezer to slow them down. For a good ant identification key, plus tips on control, visit the University of California Integrated Pest Management website (www.ipm.ucdavis.edu) or the Napa County Master Gardener help desk (see address below).

Do you really need to control ants in your garden? In the yard or garden, ants can be beneficial because they eat dead insects, animals and fallen fruit. They can also be useful for seed dispersal and soil aeration.

Sometimes ants will eat fruits and nuts, but most often they are a problem when they are tending pests such as soft scale, mealy bugs and aphids. These pest insects feed on plant sap and excrete a sugary substance called honeydew. This honeydew attracts ants; they will feed on it and protect the pests from predators. The ants will move the pests to new areas of the plant, thus spre

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By Penny Pawl, U. C. Master Gardener 

You may not realize it, but when you walk on soil you are walking on billions of creatures. I found this information on a Purdue University web site:  “Soil is alive! In fact, a single shovel full of rich garden soil contains more species of organisms than can be found above ground in the entire Amazon rain forest.” 

These microorganisms are so tiny that it takes a powerful lens to see them. They are working the soil, eating and recycling, which in turn feeds the plants that grow in that soil.

You can do an easy experiment to prove to yourself that the soil is teeming with creatures.  Water a small area well,  then layer it with newspaper (black ink only), cardboard, leaves, aged chicken manure, compost and perhaps some old lettuce or other soft plant material. Moisten each layer, then cover with black plastic, making sure all sides are secure. Don’t walk on this area, as compacting the soil will slow or even stop the process.

Peer under the plastic occasionally and you will be amazed by the activity taking place:  the cardboard and paper will be slowly disintegrating. You will see many more creatures than before, especially red wiggler worms, which love to eat decaying vegetation.  Sow bugs and millipedes will be plentiful. But the most numerous workers are the ones you can’t see: the fungi, bacteria, protozoa and nematodes.  

If you keep this spot covered long enough and keep your workers happy, the materials you layered will soon be transformed into rich, dark soil made up of worm and sow bug droppings. The soil will be well mixed because the creatures have been moving up and down in it. I have found red wigglers one foot deep in a raised bed.

Even soil that appears dry, compacted or frozen can still contain microorganisms waiting for the soil to become wet and warm again. 

Plants thrive in soil that has been amended with compost. Compost is not fertilizer. It improves the texture of the soil by separating soil particles to allow air, water and  microorganisms to move freely. When forests and open fields are left to do their own thing, soil creatures turn the fallen leaves and dead grass into humus. In cultivated landscapes like farms and gardens, we have to help the process along.

Worms are “shredders” in that they tear leaves and other organic material apart. Their work gives soil microbes more surface to feed on. All worms are not alike. Earthworms live in the top 12 inches of soil, and they sift soil through their gut, removing what they can use. In a way, they are turning the soil for you. Their castings, or droppings, are very high in nutrients that plants can use. Red wigglers eat decaying mattter. Night crawlers eat the same material, but they come out at night. 

Plant roots also aerate the soil, allowing water and nutrients to penetrate. At the same time, roots live in symbiosis with soil fungi and bacteria

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By Mary Hudson, U. C. Master Gardener

The growing season in the Napa Valley has been anything but normal this year. Our typical warm summer days were replaced by prolonged periods of below-normal temperatures, followed by brief above-normal heat spikes. 

     As a result, home garden vegetable and fruit crops were slow to start and quick to ripen. I fretted over my vegetable garden this summer, wondering when the tomatoes would finally turn red. I also recall an extremely hot Sunday that caused my pumpkin vines to wilt.

     September traditionally brings some of our warmest temperatures, but the days are growing shorter. It is time to harvest summer produce and prepare for fall and winter crops. 

     Most crops planted in early summer should be mature now, including tomatoes, carrots, chard, peppers, eggplants, corn, lima and snap beans, summer squash, cucumber, pumpkins and melons. Although you may have been harvesting these crops throughout the summer, your production is probably peaking or even waning now.

     It’s time to can or freeze soups, sauces, salsa, jams and jellies for enjoyment in winter. It’s always a delight to eat something homegrown, even if it’s from seasons past.

     You have probably already harvested most of your tree fruits, but some late-ripening plums, peaches, apples and figs may still be maturing. Be sure to continue irrigating these trees so they can withstand autumn heat.

     After gathering summer’s harvest, dig your vegetable beds deeply, amend with well-composted organic matter, and add a balanced fertilizer if you plan to grow a fall-winter garden.  Fruit trees are still actively growing even after harvest, but they should get their last watering in September. Feed with 10-10-10 fertilizer in late September or early October. Wait to prune until they are dormant. 

     Collect all fallen and spoiled fruits and vegetables. Chop them, then combine with leaves, dead-headed flowers or other organic materials from the garden and put them in the compost bin. Once these materials decompose, they can be worked into the soil to enhance your spring garden. Leaving them to rot on the ground will only encourage diseases and feed snails, slugs, earwigs and pill bugs.

      Start planting your winter garden. Napa Valley’s mild winters make it possible to grow many vegetables between now and spring. Sow seeds directly in the ground for peas, carrots, chard, lettuces, mustard, parsnips, turnips, rutabagas, beets, spinach, radishes and fava beans. Other vegetables—asparagus, broccoli, Brussels sprouts, cauliflower, celery, kohlrabi and cabbage—will perform better if set out as seedlings.   You can also plant strawberries now for a crop next spring.

     Are you interested in becoming a Napa County Master Gardener?  If so, you can pick up an application at the upcoming informational meeting on Wednesday, September 23, from 6 p

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By Cheryl Toivola, U. C. Master Gardener 

An important goal for many gardeners is to maintain a pest- and disease-free landscape. Although it is impossible to eliminate all nuisances, reducing the amount of pests is certainly achievable.

     The most effective way to reduce pests in the garden is to begin before you have even selected any plants. 

     First, start with a design that groups plants with similar needs together. Cluster plants that have comparable requirements for water, nutrients, exposure (sun or shade) and drainage.

     Then choose plants that are suited to your site. Make sure you have enough room for the plant when it reaches full size. Consider using California native plants or plants from other parts of the world that enjoy a Mediterranean-type climate. Evaluate the light, seasonal high and low temperatures and wind at the site and choose plants that can tolerate those conditions.

     Choose pest- and disease-resistant varieties when available. For example, the Crepe Myrtle is susceptible to mildew but nurseries now offer several resistant varieties, including ‘Zuni’, ‘Comanche’ and ‘Natchez’.  Many roses, such as ‘Simplicity’ and ‘Meidiland’, are also now resistant to powdery mildew. If you have existing plants in your garden that are highly susceptible to disease, consider removing them.

     At the nursery, always select the healthiest looking plants. Check the roots and avoid plants whose roots are kinked or circled. Stay away from any plants with signs of insects or disease.

     Choose plants that can tolerate your existing soil conditions. To improve the soil,  amend it with organic matter such as compost. Doing so will improve the soil’s ability to retain water. Compacted soils should be aerated periodically.

     Choose plants that will thrive within your site’s water limitations. Remember that most drought-tolerant plants will need water for their first several dry seasons but will need less as they become established. Consider your water quality. Many wells have high mineral levels that can affect plant health. Install a water-efficient drip-irrigation system and schedule it for infrequent deep watering in the early morning hours.

    Too much or too little water can kill plants. Drought conditions often stress plants and make them susceptible to pests and pathogens. Mites and leaf-suckers are more damaging to plants that are not receiving enough water. Wood-boring insects primarily attack plants that are water stressed. 

     Overwatering can also cause problems, such as root and crown diseases. Splashing water from overhead irrigation can spread fungal diseases. Our native oaks are particularly sensitive to overwatering. Too much water in the summer can predispose them to infection and disease.

     Keep your garden area clean by regularly removing diseased plants, and crush all unwanted

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