A Basil Harvest


Polenta with Anise Basil Tomato Sauce stars portabella mushrooms, Parmesan cheese, and good things from the ­garden.

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7 Basil Recipes:

Italian-Style Pesto 
Creamy Summer Tomato and Vegetable Soup 
Flatbread Pizzas with Marinated Grilled Vegetables and Basil 
Polenta with Anise Basil Tomato Sauce 
Potato and Green Bean Salad 
Salad with Purple and Lettuce-Leaved Basils 
Lemon or Anise Basil Biscotti 

Basils are the essence of the summer herb garden and culinary icons with a large and devoted following. These beautiful herbs, which belong to the genus Ocimum, display surprising aromatic subtleties due to their ability to hybridize across species lines, resulting in an almost infinite variety of aromas and tastes. The gene pool creates a plethora of clear, gemlike scents that range through lemon, camphor, cinnamon, clove, and anise. It is this diversity of aromas that both cooks and gardeners find so appealing. Like other herbs, basils are little chemical factories, producing aromatic essential oils that are contained in microscopic sacs on the leaves and stems. When a plant is brushed or chewed, the sacs are ruptured and the fragrance released.

The genus name, Ocimum, comes, appropriately, from the Greek word okimon, meaning “smell”. There are 30 to 150 basil species, depending on who’s counting, and numerous cultivated varieties. The species name of the most common culinary basils, basilicum, is the Latin translation of a Greek word meaning “king”. Basils are members of the mint family (Lamiaceae), a large amalgam of plants characterized by square stems and opposite leaves. Many are aromatic; thyme, oregano, rosemary, and lavender are other familiar herbs in the same family. A few basils are perennial in their native tropical habitats, but most are annuals, which die after flowering and setting fruits.

The genus Ocimum is like a huge extended family, filled with doting parents, favorite aunts and uncles, even the occasional oddball cousin. Your taste will determine what kind of basils you like to grow—spicy, minty, citrus, sweet, pungent, take your pick—and how much you use. Here are some general guidelines to help you get the most from your plants, preserve your harvest, and use it in the kitchen.

Growing Basil

Basils’ cultivation needs are few but important. The semitropical and tropical regions to which Ocimum species are native offer some obvious clues: warm, sunny weather and plenty of moisture. Basils do well where hot-weather vegetables such as tomatoes, peppers, and eggplants flourish; their finest growth occurs during periods when night temperatures are above 60°F. In most areas of the United States, basils thus have a limited period of rapid growth. In the mid-Atlantic states, where we live, they grow well for about 140 days, beginning in late May or early June and ending in October.

Basils grow best in a site with daylong sun, but most varieties can subsist on as little as three to four hours of direct sunlight. They will tolerate a wide range of soil conditions but will grow best in a well-drained, loamy, nearly neutral soil (pH 6 to 6.5) that is well endowed with nutrients. Good air circulation discourages fungus diseases.

Most basil species can be ­propagated from seed. (Certain cultivars are so unstable that they must be grown from stem cuttings; purple-leaved types are notoriously difficult for breeders to tame.) Seeds may be sown directly into the garden after the frost-free date, or they may be started indoors four to six weeks earlier, which gives the gardener a head start and permits additional harvests. Space transplants or thin seedlings to 12 to 18 inches apart.

Water regularly—about 1 inch of water per week in the absence of rain—and give the plants a fortnightly draft of liquid fertilizer. Basils are fast-growing, heavy feeders; big yields are the result of steady growth and rich soil.

Harvesting Basil

How much basil should you grow to meet your cooking needs? To determine plant yields, we experimented with ten varieties of culinary basil, growing them both in gardens and in containers, and we made some surprising discoveries. Although it is commonly believed that big-leaved basils produce a greater volume and weight of leaves than those with small leaves, we found that growth rate and frequency of harvest may be more important determinants of a plant’s total yield. We also found virtually no difference between the yield of basils grown in the ground and those grown in containers. The top producer was a pot-grown ‘Genoa Green’, which produced a total of 27.5 ounces leaves over the course of the season. The least productive was the large-leaved but slow-growing ‘Purple Ruffles’, which produced just under 11 ounces; lemon basil, with its smaller leaves, outperformed it with 14.5 ounces. Our test plants produced an average of 13 ounces, or about 7 cups of leaves per plant.

During their summer growth, basil plants are desperate to flower and set seed. That’s the way to preserve the species, and it may help farmers and florists, but it sure cuts down on the amount of pesto that can be made from a single plant. As soon as stems begin flowering, their foliage production ends; however, home gardeners can combat basils’ drive for flowers by pruning plants heavily to keep them producing foliage all summer. Start pruning when the plant has six to eight pairs of leaves. Don’t just nip the flowers as they form; instead clip off all but two to four leaves. Within as little as three weeks, the pruned stem will have regrown two to four new, harvestable branches.

Storing Basil

Basil is best when used minutes after it is picked. To keep basil fresh for a day or two, place the stems in a jar of water away from sunlight. To have it fresh for seven to ten days, cover the jar and stems loosely with a plastic bag and place in the refrigerator.

Keeping basil for longer periods of time can be a problem. Freezing turns the leaves dark and flavorless.

We have for many years preserved basil by packing the leaves in jars with extra-virgin olive oil and refrigerating them—the flavor of the leaves preserved this way is remarkably close to fresh basil. We’ve never experienced a problem, but we can’t recommend this as an option because there is a strain of toxic botulinum spores that can germinate in oil even at refrigerator temperatures. To prevent growth of the spores, one would have to increase the acidity substantially by adding citric acid, available where canning supplies are sold, or vinegar; or use up the basil packed in oil within about three weeks.

Perhaps the best way for most people to preserve their basil harvest is to make and freeze batches of wonderfully flavorful pesto, which can be thawed easily and used in many ways. When freezing pesto, leave out the garlic; instead, chop and add some fresh garlic when you’re ready to use the pesto. Adding a small amount of chopped fresh parsley to the thawed pesto will give it a greener, fresher taste; you can also add more Parmesan cheese.

Basil is also traditionally preserved by hanging in bundles to dry or by laying stems on screens in a well-­ventilated spot away from direct sun. When they are crispy, strip the leaves from the stems, pack the whole dried leaves in clean jars with tight lids, and store them in a cool, dark place for as long as a year. Always dry your basil leaves whole, then crumble them into your preparation as needed. Once crushed, dried leaves lose their essential oils and ­fragrance rapidly.

During their summer growth, basil plants are desperate to flower and set seed. That’s the way to preserve the species, and it may help farmers and florists, but it sure cuts down on the amount of pesto that can be made from a single plant. As soon as stems begin flowering, their foliage production ends; however, home gardeners can combat basils’ drive for flowers by pruning plants heavily to keep them producing foliage all summer.

Using Basil

Cooks around the world use basil with fresh and cooked vegetables, in ­salads, with eggs, meats, and seafood, in soups and breads, with all kinds of cheeses, and for seasoning vinegars and oils. Accompanied by fresh tomato slices, it is wonderful in a sandwich in place of lettuce, and it adds a pleasant flavor to butter, vinaigrettes, marinades, and sauces.

Cook fresh basil only briefly or add it as a garnish to long-simmered ­dishes. In some recipes, such as in pesto, dried basil just won’t work: the fresh herb is essential. Otherwise, when substituting dried basil for fresh, use only about a third as much as you would fresh. It is always best to season lightly at first, taste, and then add more dried basil if ­necessary.

If a recipe calls for packed basil leaves, press them down in the measuring cup to measure. In recipes that specify nonreactive pans, don’t use aluminum, iron, or copper, which can react with the acid in the food.

Tom DeBaggio is an herb grower and author in Arlington, Virginia; Susan Belsinger gardens, cooks, and writes in Brookeville, Maryland. This article is an excerpt from their book, Basil: An Herb Lover’s Guide, to be published in September by Interweave Press.