By Susanne von Rosenberg, UC Master Gardener of Napa County
One of the reasons I really enjoy having fruit trees is that they are perennials: they give back a lot for relatively little effort. You can get the same benefits from perennial vegetables.
The most common perennial vegetables for our area are artichokes, asparagus and bunching onions (scallions). Others that are highly suited to our Napa Valley climate are cardoon (a relative of artichokes), tree collards (also known as tree kale or walking stick kale), walking onions (also called Egyptian onions) and nopales (prickly pear cactus pads). Additional options include sunchokes (Jerusalem artichokes), perennial arugula (caution: it self-seeds readily) and miner's lettuce (claytonia). In our climate, miner's lettuce acts like a self-seeding annual, but it is a perennial in areas where it receives sufficient moisture.
In addition, you can “perennialize” regular kale, garlic (for green garlic) and, to some degree, Swiss chard and broccoli. To start treating regular kale as a perennial, simply cut it back to a few inches of stalk when it starts to look tired and it will resprout. You can do the same with broccoli. You won't get another large head, but you will refresh the plant and get more small side shoots.
In my yard, Swiss chard readily self-seeds, so there is always some chard growing wherever I water regularly. If it's not in the way, I let it grow. If you plant garlic and don't harvest the bulb, it will sprout as a cluster of green garlic the following growing season and continue to create bulbs underground. Eventually, as with flower bulbs, you will have to dig it up and divide it. Keep some of the best bulbs and replant some cloves for more green garlic.
Think about the pros and cons when you consider adding perennial vegetables to your garden. The main advantage is that you only plant once, yet you harvest for multiple years. Because the plants stay in place longer, they develop stronger and more extensive root systems. This helps the plants take better advantage of available water and nutrients.
Because you're not replanting every year, you're protecting the soil ecosystem. For busy people, adding one or two perennial vegetables per year can be a way of building a productive vegetable garden without investing a lot of time.
You can also let the plants flower, which supports pollinator insects. Some perennials add beauty to your garden. Sunchokes, which are part of the sunflower family, will grow 8 to 10 feet tall with adequate water and produce numerous small sunflower-like flowers.
However, there are some downsides. First of all, you lose flexibility. You have to carefully consider how big the plants will get and whether they make sense at full size in their proposed location. Good locations for perennial vegetables include areas adjacent to other perennials (including berries, fruit trees and ornamental plantings), at the ends of annual vegetable beds and in groupings with other perennials that have similar water needs.
For many perennial vegetables, it takes longer to get harvestable produce. Also, you may need to keep watering them when the weather is dry. When we have a light rainy season, you'll likely have to keep irrigating.
If you are not rotating vegetables and you are keeping them alive year-round, you may have more pest problems. Control pests as soon as you notice them. If you have gophers, you may find that certain perennial plants, such as artichokes, need to be planted in cages because the roots are just too tasty for gophers to resist.
Finally, because you are continuing to water, you are also likely to continue to get weeds, so you will need to cultivate around the plants or mulch regularly to keep the weeds down. Also make sure to check that you are selecting the right kinds of perennial vegetables for your garden. Many common perennial vegetables, such as watercress, require relatively high amounts of water or need sandy, well-drained soil. Others can become invasive. Do your research or contact the Master Gardener help desk for more information.
There are many other perennial vegetables to try if you're adventurous. On the border between herbs and vegetables are sorrel and lovage, which can be used as salad greens, in soups and as seasonings. Daylily tubers, young shoots, buds and flowers are all edible. The leaves of scorzonera (black salsify) can be harvested and eaten just like lettuce. (If you harvest the edible roots, however, you will kill the plant.) Sweet potato leaves are also edible, as are linden tree leaves. Have fun diversifying your garden!
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Is there an easier crop to grow than arugula? Also called rocket, arugula is available from many seed suppliers and garden centers, which commonly sell one of two types: wild Italian arugula (Eruca selvatica) and common arugula (Eruca sativa).
Wild Italian arugula has delicate, peppery foliage and blossoms and small nutty leaves that make it more suited to salads than cooking. It is more heat resistant than common arugula, although heat is usually not a problem at this time of year. Italian arugula germinates in about 14 days. Soaking the seed for a few hours (no longer as seeds need oxygen) may speed germination. Baby leaves will be ready to harvest in seven to eight weeks.
Common arugula germinates in about ten days and is ready to harvest about five weeks later. Common arugula is also peppery and nutty, but its leaves are larger and softer than the wild arugula leaves. When filled out, a plant may reach six inches in diameter.
Neither type of arugula transplants well. Sow seed directly where you would like arugula to grow.
Arugula is forgiving as far as soil is concerned. A neutral soil, consistent moisture and a well- prepared bed with added compost will certainly boost your harvest, but even newly turned soil can produce an abundance for autumn meals.
Sow seeds directly in the ground in shallow furrows three to four inches apart, or broadcast the seed. Cover with about a half-inch of soil and keep the patch damp through the growing cycle. To deter birds and slugs and get your beds off to a strong start, consider using row covers.
Arugula is ready to pick as soon as the leaves start to fill in and show their lobes. A small, shoebox-sized patch sown every couple of weeks through winter will keep you supplied with arugula.
If your garden center does not carry arugula seeds, or you would like to try different varieties to find one that is spicier or milder, here are some suggestions.
Territorial Seed (www.territorialseed.com) offers five varieties, including ‘Roquette,’ which is especially good for salads. It is frost hardy and grows 12 to 18 inches before bolting. Come spring, let it flower and self-sow to assure an abundant future crop.
‘Dragon’s Tongue’ is a beautiful variety from Territorial. Its leaves are deeply lobed and a striking deep green with red veins. It is also frost hardy and reportedly not bitter even when it approaches 18 inches in height. I want to grow this one just for looks.
Renee’s Garden Seeds (www.reneesgarden.com) has an interesting arugula selection. One that caught my attention seems to be an addition to the two families above. Wasabi arugula (Diplotaxis erucoides) forms pretty, leafy rosettes that have the spicy, startling flavor of horseradish. Its little flower stalks with dainty white blossoms are a special spicy delicacy. Add them to salads, sushi and pasta dishes. They make a memorable and surprising garnish.
Picking arugula flowers for salad will not only enhance your meals but will also keep seed heads from forming. If you want the arugula to self-sow, leave some flowers to set seed. To harvest, you can uproot the whole plant, pick individual leaves from the outside in, or use the “cut and come again” method, leaving roots in place to sprout new growth.
The best arugula salads are simple. A few years ago I cooked with a woman who had been private chef to Charles Schwab until she tired of the traveling. Soon after she gave up her post, she got a frantic call from her replacement, begging for her arugula salad recipe, a house favorite. Laughing, she gave him the recipe: put chilled arugula leaves in your salad bowl. Drizzle with a good extra virgin olive oil and toss until the leaves are lightly coated. Squeeze fresh lemon juice over the leaves, toss again, and season to taste with salt. Finish with shavings of a dry cheese, like Vella Dry Jack.
Need more ideas? Scatter a few fresh leaves on top of pizza or flatbread; use in sandwiches in place of lettuce; or add the peppery leaves to soups garnished with sour cream or crème fraîche. Experiment with arugula in place of basil in winter pesto. Arugula is easy to grow and a healthy addition to the winter kitchen.
Workshop: Napa County Master Gardeners are hosting a workshop on “Fruit Tree Selection and Planting” on Saturday, November 16, from 9 a.m. to noon. The workshop will be held at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Learn what to consider when choosing deciduous fruit trees for your garden and microclimate. Learn about bare-root trees and how to plant them. Online registration (credit card only)
Mail in registration form (cash or check only)
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.