Growing from Seed
Basil seeds should be sown thinly and covered with approximately a quarter-inch (0.5 cm) of compost or fine soil. Keep the soil moist and free from weeds. Germination should occur within 5-7 days. Just so you don’t mistake it for a weed… new seedlings have two broad leaves. Once the seedlings have two pairs of leaves you can thin out the weaker seedlings. Most sources suggest thinning the plants to be 6-12 inches apart; however in my experience with common basil, I find it does well with a little more room to grow. I have had basil plants grow to be 24 inches wide.
If you want to get a head start, the seeds can be started indoors 3-4 weeks before the last spring frost. You can sow the seeds ½-inch apart in flats, keep them warm and moist, and then transplant them after they have two pairs of leaves.
Care should be taken not to plant basil outdoors until after the last spring frost has passed. It prefers full sunlight (6+ hours a day of direct light) and a warm climate, meaning more than 70 °F (21 °C) during the day and no colder than 50 °F (10 °C) at night. The herb should be planted in soil that drains well. It does best in soil that is combined with compost. Basil grows in soil that has a wide range of acidity (pH levels between 5.1 and 8.5) although levels between 5.5 and 6.5 are preferred.
Basil should receive 6 or more hours of direct sunlight a day. Some suggest watering outdoor plants every 4-6 days, but I personally like to check mine every other day to determine if the soil is moist. If the soil is dry I will water them, otherwise I wait another day. In my experience, it is hard to over-water outdoor basil, especially if the plants are in good soil that drains well. For indoor potted plants, water them until the soil is wet to a depth of about 1½ inches. The best technique for watering your basil is to do so at the base of the plant to avoid stressing the leaves and stems.
If you are repeatedly growing in the same spot outdoors, the leaves of your plants are yellowing or you are growing basil indoors, then you may want to fertilize. You should fertilize only once or twice per growing season for outdoor plants. It is recommended, for edible herb and vegetable gardens, to use a balanced fertilizer where the nitrogen content does not exceed 20 percent. A typical fertilizer that would be recommended for edible gardens is one rated 10-10-10 (the percentage of nitrogen, phosphorus and potassium in the mix, respectively). Stronger fertilizers should only be used when plants are being watered thoroughly and the drainage is good, to help prevent fertilizer burn.
Your basil plant should be pruned several times throughout the season. This will encourage new growth and is especially important if using the herb for culinary purposes. This can be done after the plants have grown at least 6-8 inches. When harvesting basil, I prefer to cut a stem just above a pair of leaves. Leaflets next to the topmost leaves are then converted into new stems. After several months of growth your plant will begin to flower and form seed. At this point the basil will grow more slowly if the flowers are not pruned away, and it will begin to turn bitter to the taste. Simply remove the entire flowering part from the stem by cutting or pinching.
Getting Rid of Basil Pests
No garden would be complete without a few residents making their homes in or around your basil plants. Some creatures can be beneficial to the garden environment while some are bad for your harvest. I have compiled a need-to-know list of some of the most common problem makers when it comes to growing basil and what you can do to get them under control.
Help! Common Problems with Growing Basil
Solutions to common problems experienced while growing basil.
Migrating for the Winter
Well, basil plants don’t migrate on their own, but if you want to prolong their life you can transplant them into containers and move them into a warm, sunny location indoors. You must do this before first frost. Basil will do best near a south-facing window (if you reside in the northern hemisphere) or it can be grown under certain types of grow lights, as described in How to Grow Basil Indoors. The good news is that you can enjoy basil all year round!Once your basil plant has reached 6-8 inches in height you can begin harvesting leaves. This involves exactly the same process as “pruning”. Harvesting basil is important, not only to promote the growth of new stems but to ensure that the plant does not flower too early. Once the herb starts to flower it will stop producing new leaves and the existing leaves may become slightly bitter to taste. If you are growing basil outdoors make sure to harvest all the leaves before the first frost, or transplant it indoors so that your crop is not lost.
Preserving the Herb After Cutting
There are many ways to preserve basil. This means that you can have basil available all year round, especially if you are growing basil indoors as well. Now let me break down the various ways that basil can be preserved.
Keeping Fresh Cut Basil Fresh
Basil loves warm weather, and furthermore it does not like your refrigerator. Putting basil in the fridge will cause it to wilt and turn brown. To keep basil fresh for several days after cutting it, put the basil into a glass of water with the stems down. Make sure the leaves are not in the water and sit it out on the counter-top or somewhere close by. If you insist on using the refrigerator, cover the basil with a plastic bag while it is in its container or glass to help protect it.
This is a great method for preserving basil if you do a lot of cooking and you want to have relatively fresh basil all year long. Take the basil from your harvest and, after washing it, put it in a food processor. You can even use the stems if you wish. Puree the herb, pour it into ice cube trays and put it in the freezer. I recommend using a little extra virgin olive oil in the puree, especially if you are going to be making pesto with it. After the cubes are frozen you can pop them out and store them in zip-lock bags. When you are ready to cook, it’s as easy as tossing a few cubes in the pan.
There is an art to drying basil and there are a variety of methods people use for doing so. One caveat to drying basil is that it turns brown, and this is a turn off for many people. This is why many people prefer to use fresh basil or freeze it instead. If you are wholeheartedly convinced that you want to preserve your harvest in this way.
First, you will need to harvest the basil leaves. The best time to do this is mid-morning, after any morning dew has burned off and before it gets hot and the leaves start to wilt. When you go to collect the leaves, take as much from the plant as you desire. However, if you want to encourage new growth after harvesting basil, make sure to cut each of the stems of the herb directly above a leaf node.
Second, you will need to prepare the leaves for drying. Removed any noticeably damaged or diseased leaves at this time. Shake the stems of each bunch vigorously to make sure any resident insects are thrown from the basil. Rinse the herb under a gentle stream of cold water and remove any soil that may remain. Dry any excess moisture from the leaves. This can easily be accomplished by layering the leaves between sheets of paper towels and applying a gentle dabbing pressure until the leaves are mostly dry.
Now that the preparations are complete, there are various methods that can be used to dry basil. This herb has a relatively high water content compared to other herbs, weighing in at 91% water by weight. This means that it is not the best candidate for drying naturally and so dehydrator drying or oven drying is your best way to go. If the herb stays wet for too long it is susceptible to mold. Any leaves that grow mold during the drying process should be thrown out. Here are some methods for how to dry basil leaves.Food DehydratorThis is the easiest method, but you need to have a food dehydrator. Simply dry basil leaves at approximately 95 degrees for 1 to 3 hours. Remove the stems once the herb is dried. It is my understanding that this Nesco Food Dehydrator is the bees knees.Traditional OvenEven though high temps will dry basil faster many people say that it damages the essential oils, so I recommend using relatively low temperatures in an oven. Turn your oven on to the lowest possible setting (usually around 140° F) and get it warm. Place your basil on a cookie sheet. Now turn the oven off and place the basil in the oven. After an hour of drying you can turn the oven back onto the lowest setting for ten to fifteen minutes. You can repeat this every hour until the herb is brittle, which means it is dry.Hang DryOne method for drying leaves is to hang bunches, upside-down by the stem, in a warm, dry, well-ventilated room for a week or more. You can run a sort of “clothesline” in a quiet, undisturbed part of your home from which basil can be hung. Use twisty-ties or twine to hang the basil herb upside-down from the clothesline by the stem. Once the basil is brittle to the touch it is dried.
Regardless of the method you use to dry your basil, once the herb is dried strip the leaves away from the stems and store the leaves in airtight containers away from sources of light and heat. If properly dried and stored, basil will keep for about a year. Now that you’ve taken all that care growing basil, you can enjoy it all year long!
Potential health effects
Recently, there has been much research into the health benefits conferred by the essential oils found in basil. Scientific studies in vitro have established that compounds in basil oil have potent antioxidant, antiviral, and antimicrobial properties, and potential for use in treating cancer. In addition, basil has been shown to decrease the occurrence of platelet aggregation and experimental thrombus in mice. It is traditionally used for supplementary treatment of stress, asthma and diabetes in India. In Siddha medicine, it is used for treating pimples on the face, but noted that intake of the seeds in large quantities is harmful for the brain.
Basil, like other aromatic plants such as fennel and tarragon, contains estragole, a known carcinogen and teratogen in rats and mice. While human effects are currently unstudied, extrapolation using body weight from the rodent experiments indicates that 100–1000 times the normal anticipated exposure still probably produces a minimal cancer risk.