Sweet Genovese Basil is an Italian variety perfect for pesto and all types of recipes. All Basil plants are annual which means that they only live through one season. Generally this is around 4-6 months depending on your local climate. The plant generally can grow to 1 1/2-2 feet tall.
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Outdoors the plant will be happy with the temperatures between 50 and 90 degrees. Anything above or below those temperatures will cause the plant to suffer and eventually die. Using a mulch will insulate the soil from the heat of the day and improve this situation greatly. To grow Sweet Basil of all types, the daytime temperatures must be warm but not too hot (around 75-90 degrees) and it must get at least 3-4 hours of sunlight a day. It can be grown with filtered light all day such as under a tree or in a bright window indoors.
If basil gets too hot, dry or if it becomes pot bound the plant will begin its flowering process which signals the end of its life. It rarely produces more tasty leaves after the flowers appear. It is important to keep the soil moist and somewhat cool and in a large pot, as well as pinching off the flowers that begin to form. The longest a basil plant will grow is about 6 months in the ground, about 3-4 months in a pot. Many people do not give the plant's roots enough room to grow and they become pot bound very quickly. This causes the plant to get too dry, too hot, and just plain cranky. It will eventually start to look yellow and the leaves will get smaller and the flower stalks will appear. At this point the plant will die and you probably cannot save it. You can however start a new plant and put it in a partly shady, cooler place in summer or indoors for the winter and still have great fresh basil.
What is eating my basil?
It is likely caterpillars or grasshoppers and may possibly be snails or slugs.
The easiest way to get rid of the caterpillars is by looking for them and removing them by hand. Look under all the leaves and see if you find any droppings they have left behind.
If so, that is definitely caterpillars.
If you find no evidence of worms, then it is likely grasshoppers but they are generally easy to see, when you disturb the plant, they jump up. Slugs and snails come out only at night but you can make a circle barrier of crushed eggshells and that should stop them from climbing up the stalks. Copper tape works great and a new product called Sluggo is a natural poison safe to use in the garden.