Learn How to Grow Basil
By Kris Wetherbee | Jun 10, 2014
Decades ago, I never thought much about growing basil, especially since that bottle of dried basil in my cupboard seemed to suffice just fine. Then one summer afternoon, my friend invited me over for lunch to enjoy her homemade chicken and basil quiche. The aroma was enticing, and the flavor an unexpected surprise, with slightly peppery undertones and hints of licorice, cloves and thyme. The quiche had so much more depth of flavor than I was used to, simply because my friend had used fresh basil instead of dried.
Since that day, basil (Ocimum basilicum) has remained one of my three favorite fresh herbs in the kitchen, and has secured a permanent place in the annual summer garden. And for good reason — it not only tastes great, it’s also relatively easy to grow, unless of course you discount how downright difficult it can be to choose which varieties to plant. The choices have expanded even more in the last few years, making this decision anything but straightforward!
What to grow
There are more than 150 different types of basil: Many excel in foods, some are used primarily for medicine, and others are highly ornamental. Thankfully, not all types are easily found in seed catalogs and nurseries. But there’s still a surplus of common varieties to choose from, all of which range in colors, flavors, textures and forms.
The most common culinary type is often referred to simply as sweet basil. These varieties have higher concentrations of certain volatile oils that create a relatively sweeter basil flavor. Other types may have accents of lemon, lime, clove, cinnamon, licorice or even mint. Lemon basil, for example, contains citral and limonene oils, resulting in a similar sweet basil flavor heightened by lemon. The overall composition of these volatile oils is what ultimately determines the taste and aroma.
Along with a basil’s flavor profile, its ornamental value, landscape use and ease of growing can also play a part in deciding which varieties to grow. Christmas basil combines all three and looks stunning in the garden or containers, with extra-large, showy purple blooms and a nice fruity aroma.
If you’re looking for color interest in addition to green, Dark Opal gives you both, with a striking variegation of mostly purple leaves with green accents. Red Rubin is striking with its copper-tinged purple leaves, and Amethyst Improved is nearly black in color. Pairing any of these with marigolds or other plants with gold or yellow flowers or foliage makes for an eye-catching contrast.
Some of the newest varieties on the scene offer rich possibilities in the garden and kitchen. Profumo is a Genovese-type with rich, clean flavor, just right for when you want classic basil taste — and it equally excels in the garden, with somewhat large leaves that grow densely on mounding, compact plants. It is the perfect choice for use as an edging plant or for growing in small spaces or containers. Bush varieties in the past have offered only small, thin leaves to match their compact size. As a result, Profumo is my compact plant of choice when it comes to kitchen use.
One of the more recent varieties with outstanding garden-to-table characteristics is Pesto Perpetuo. Not only is this variety perfect for pesto, it’s also stunningly beautiful, with light green and cream variegation on the edge of its leaves. One of its most prized virtues is that it’s non-flowering, meaning you don’t need to pinch the flowers in order to prolong the harvest.
As a classic summer herb, basil needs plenty of sunlight and warmth. Choose a site that gets at least six hours of direct summer sun each day if bountiful harvests are your goal. Unlike most culinary herbs of similar origin, however, basil also needs a fairly rich soil for quality production and continual harvests.
Before you plant, work in a generous amount of compost or well-aged manure into the soil. This will not only provide nutrients for plants to grow, but will also improve drainage in clay soil and increase moisture retention in sandy soil.
This mint family member also needs plenty of moisture to grow and produce those big, lush leaves. Its moisture needs are similar to spinach or lettuce, so water accordingly. The key is to keep the soil consistently moist, but not damp. Otherwise, plants and subsequent harvests will suffer if the soil remains dry for extended periods. Mulching plants as soon as summer warmth settles in will help keep the soil moisture more even.
Basil is a heavy feeder, especially when it comes to nitrogen. That’s why I sidedress with additional aged manure, rich compost or compost tea a few weeks after planting and again in midsummer to encourage succulent growth and give plants the added boost they need. Any high-nitrogen organic fertilizer will do just fine.
There are some years that I start my own seeds indoors for transplanting after all danger of frost has passed, and there are other years that I have sown seeds directly into the ground. If my spring is especially busy, I will buy transplants from my local farmers’ market, garden center or nursery. Either way, I’ve learned that the end of spring frosts does not determine the best time to plant. Yes, you do need to wait until after all danger of spring frosts have passed before sowing seeds outdoors or transplanting, but the temperatures at night are what determine the best time to plant.
Wait until nighttime temperatures remain above 50 to 55 degrees before setting out transplants; wait until soil temperatures have warmed to 60 degrees before directly seeding in the ground. Seedlings may succumb and plants will become stunted if temperatures remain below 50 degrees for any length of time. Case in point: Though our average last spring frost is April 15th, basil transplants that go into the ground in June typically grow faster and outperform similar sized plants set out in early May. As such, I’ve learned that it pays to be patient.
When sowing seeds in the ground, plant them just beneath the surface, or scatter them on the soil, then cover with a thin layer (1/8 to 1/4 inch) of compost, potting mix or vermiculite. Be sure to keep the soil evenly moist as seedlings can take up to 30 days to germinate, especially in cooler spring soil.
Set transplants or thin seedlings to stand at 10 to 12 inches apart. Space compact varieties 6 to 10 inches apart; space well-pruned and vigorous varieties 16 to 24 inches apart. Frequent harvests and pruning encourage bushy and more vigorous plants.
Insider growing tips
Basil is easy to transplant at most any size, but 2- to 6-inch-tall seedlings work best. One exception is lemon basil, which should be directly seeded where it will grow, as it does not adjust well when transplanted. Sweet basil types, however, are quite sturdy and are easy to transplant up to 10 inches tall. The added bonus is that taller transplants survive destructive nighttime raids from slugs and snails better than smaller seedlings.
Keeping weeds at bay will help slow down slug and snail populations, as does hand-picking, beer traps or copper flashing. However, the best control method for me by far has been the introduction of decollate snails, a natural predator of slugs and brown garden snails. We released the decollates about 15 years ago and have had little to no problem with slugs since.
As I mentioned earlier, basil is very sensitive to cold. If temperatures drop below 38 degrees, the leaves will actually blacken. Sometimes, though, I take a chance and plant my basil in mid-May. Weather patterns can be very subjective, and there are times I don’t want to delay growing basil until late June just to avoid a potential chilly night or two in the 40s. That’s when a row cover comes in handy. If the plants do become a bit set back by cold, I simply water them for the next couple of weeks with a liquid fish fertilizer or compost/manure tea to get them out of their slump.
Pointers for a productive harvest
Harvest leaves frequently for a bushier and more productive plant. Start by pinching off the tip clusters when plants reach 6 to 8 inches tall; two weeks later, pinch off the center stem just above where the lowest side-shoots branch off. Always pinch above a leaf node — the joint in the stem where the leaves grow. That way, new branches will form and grow where the nodes remain, producing a multi-stemmed, lush and bushy plant with lots of harvestable leaves.
When the plant has several branches and is 12 to 18 inches tall, cut it back by two-thirds. This first big harvest is the perfect opportunity to make several batches of pesto. The remaining plant will regrow and be ready to harvest in another two to four weeks for continual harvests.
Frequent pinching of tip clusters and cutting plants back not only produces a bushier and more productive plant, it also delays flowering. Your best harvests are before the plant flowers. Pinching back the flowers as they form will result in larger leaves and better harvests.
Once the flowers take over, the leaves become smaller and less abundant, and its essential oils — and flavor — diminish. There’s no need to fret too much if the flowers get ahead of you, though, as you can still use the leaves until the flowers form seed. The flowers are tasty tossed in salads, stir-fries or soups, and the entire plant — leaves, flowers and stems — can be used to make a great-tasting basil vinegar.
One last tip: When you do harvest your basil, you can keep it fresher longer by treating it like cut flowers in a vase or glass of water on the kitchen counter, where it’s always close at hand. And by changing the water daily, your basil bouquet will maintain its fresh flavor for up to 10 days.
There you have it — everything you need to know for the best-tasting basil you’ve ever had. Be careful, though — once you grow your own, there’s no going back.
More on Growing and Cooking With Basil
• Easy Pesto Recipe With a Twist
• Basil-Lemon Ice Cream Recipe
• Roasted Tomato Basil Soup
• Chicken Sandwiches With Lemon-Basil Zucchini Ribbons and Boursin Cheese Recipe
• Ten Profitable Spices to Grow
• Best for Pesto: Genovese, Italian Large Leaf, Mammoth Sweet, Napoletano, Pesto Perpetuo, Profumo, Red Rubin, Sweet Basil, Lemon, Lime, Christmas
• Best for Cooking: Any of the pesto-type varieties, Amethyst Improved, Lettuce Leaf
• Best for Fish and Meat Dishes: Lemon, Lime, Christmas, Italian Large Leaf, Siam Queen, Sweet Basil, Sweet Dani
• Best in Sandwiches and Burgers: Genovese, Italian Large Leaf, Mammoth Sweet, Red Lettuce Leaved, Sweet Basil
• Best for Wrapping: Italian Large Leaf, Mammoth Sweet, Napolitano, Red Lettuce Leaved
• Best in Salads: Dark Opal, Italian Large Leaf, Lettuce Leaf, Mammoth Sweet, Purple Ruffles, Red Lettuce Leaved, Sweet Basil
• Best in Stir-Fry and Thai Cuisine: Christmas, Holy Basil, Lemon, Purple Ruffles, Red Rubin, Sweet Basil, Siam Queen, Thai
• Best in Fruit Salads, Desserts and Baked Goods: Cinnamon, Lemon, Lime, Siam Queen, Sweet Dani, Thai
• Best for Tea: Cinnamon, Holy Basil, Lemon, Mrs. Burns’ Lemon, Purple Ruffles
• Best for Herbal Vinegars: Any pesto type, Cinnamon, Dark Opal, Greek Basil, Lemon, Mrs. Burns’ Lemon, Purple Ruffles, Red Rubin, Siam Queen, Spicy Bush Basil, Thai
Kris Wetherbee and her husband, Rick, grow all sorts of wonderful basils in their Oakland, Oregon, garden.
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