Does Basil Like Cold Weather?
Basil is an easy and popular herb to grow, especially common or sweet basil (Ocimum basilicum). This member of the mint family is grown for its sweetly scented leaves used either fresh or dried that compliment a variety of foods. A member of the mint or Lamiaceae family, basil is usually grown as a tender annual. Generally, its growth cycle doesn’t include overwintering; rather it dies down and the hard seeds wait in the ground over winter and then germinate during the spring thaw. When temperatures dip, basil suffers cold damage almost immediately in the form of blackened leaves. Therefore, basil and cold weather do not gibe. If, however, you are the lucky owner of a greenhouse or live in a region where temps may dip but long hours of sun prevail, it is possible to try and over winter your basil baby indoors.
Basil Cold Hardiness
The cold tolerance of basil begins to suffer when the mercury drops into the 40’s (F.) but really affects the plant at 32 degrees F. (0 C.). The herb may not die, but basil cold damage will be in evidence. Keep in mind the cold tolerance of basil and wait until overnight lows are above 50 degrees F. (10 C.) before setting out transplants. If you set them out prior to temps in the 50’s (F.), you’ll either have to dig them back up or cover them to protect this tender herb from cold snaps. It is also advisable to mulch 2-3 inches (5-7 cm.) of grass clippings, straw, compost or ground up leaves around the basil plants. This will aid in retaining moisture and retarding weeds, but also protect the plant a bit in the event of a sudden, short cold snap. You can also cover the tops of the plants, down to the soil to help trap heat. If the cold snap really drops the mercury, a string of Christmas lights beneath the covered basil plants will help retain some heat under their covering. There may be some minor basil cold damage, but the plants will likely survive.
Basil and Cold Weather
Once the mercury falls into the 50’s and it seems that it is likely to continue to dip, make a plan for the basil plants. You may just choose to harvest as many leaves as possible and dry or freeze them. Or, if there is plenty of sunshine during daylight hours and temps are over 50 degrees F. (10 C.) but dip down at night, leave the basil outside during the day and then move it indoors at night. This is a temporary situation and will prolong the life of the plant, but it will eventually expire as temperatures continue to drop. Lastly, you may want to try to get the basil to survive the winter so you will have fresh leaves year round. In this case, you will need to pot the basil and bring it inside. Remember, basil requires lots of light — six to eight hours of direct sun or ten to 12 hours under artificial light. Also, basil is still an annual and as such, it will eventually flower and die, even when brought indoors. That is its life cycle. Additionally, if you do not have the light or space to try and over winter the herb, you can take tip cuttings from the basil and root them in small containers kept on the windowsill. You’ll have to keep an eye on the cuttings, as they tend to grow towards the light and may come in contact with a frosty window, which will result in blackened leaves.
