Overwintering Your Herbs Indoors
The weather is cooling and Fall is definitely in the air. This means it is time to think about ways to keep your more tender herbs safe over the winter months and one of the best ways to do this is to overwinter the plants indoors. If you can grow herbs outdoors, you can grow them indoors this winter.
Most herbs are tough by nature, but some take to an indoor climate better than others Don’t bother with annuals, such as basil (although I will mention something about this herb later), dill, poppy, borage or cilantro; these herbs already have exhausted themselves in the garden. They will just get scraggly and die inside so why waste the time and space.
Instead, focus your over-wintering efforts on tender perennials, such as rosemary, bay, tender lavenders, scented geranium and lemon verbena; and herbs that are compact and/or have trailing stems, such as thyme, mint and winter savory. I say compact or trailing because unless you have a glassed sun room you probably can’t have a small tree in your living room!
I like to bring in a pot of calendula in late September to harvest a bit longer indoor. It is an annual but you can keep it going a for quite a while indoors, by pinching the flowers off just as they bloom. This is a great way for you to keep adding the lovely carotenoid rich petals to your cooking and tea in the winter months.
I mentioned basil earlier – I have had success with bringing basil in and cutting it back half way. It seems to last then until late winter as long as you trim it regularly and give it lots of light. However, it is an annual and it is definitely not going to last long indoors.
So here are some general guidelines for overwintering the herbs indoors to help you have success.
The first thing to do is beat the frost -aim to dig and pot your plants at least a few weeks before your first expected frost. Better yet: Bring herbs indoors when outdoor daytime temperatures are 18 -21C degrees (about the same as indoor temperatures).
The next step is to choose the right pot -what I mean is that if you are digging the herb out of the garden you will need to choose the best pot to put it in. Choose a container slightly larger than the root ball of the plant; or use a large window box-style container to hold several smaller herbs. Plastic pots are lighter and more portable than terracotta; they also retain water better than unglazed clay pots. Keep in mind that plants need less water in winter, however. If your home tends to be warm and dry, choose plastic pots; if it’s cool and humid, terracotta could be a better choice. Be sure any pot you use has drainage holes.
Next, you'll want to consider is the soil you use. Use a good-quality commercial potting mix—or a homemade blend of compost, vermiculite and peat moss—but never garden soil. Garden soil often is too heavy, drains poorly and can harbour insects, disease pathogens or weed seeds.
With less daylight in winter, plant growth slows, so less water and fertilizer are needed than during spring and summer. I would recommend not feeding at all until active growth resumes in late winter, and I water most plants only every two weeks. But I do mist frequently because humidity usually is low in winter.
Also keep in mind – spray away insect pests. Don’t risk bringing pests indoors. After potting garden herbs, spray them thoroughly with a soap-based spray to keep scale, mealy bugs, spider mites and other common pests from hitching a ride inside. A good preventive spray can be made of soap, garlic and chilies (I’ve posted my recipe at the end of the article).
You also want to take time to trim. This is good time to give plants a light “haircut”—trim back the top third of plants to encourage strong new growth, and to help compensate for root loss.
In terms of bringing things indoor – move gradually. Your plants will barely notice the change if they have time to adjust gradually to their new conditions. Just as plants benefit from “hardening off” (gradual acclimation) in spring, they do better with a similar but reverse process in fall. If possible, start by moving them to a bright but sheltered location outdoors, such as beneath a tree, for a week before moving them indoors.
And the final steps you need to consider…
For best results, replicate outdoor growing conditions as much as possible.
Choose a bright, south-facing window; or place plants 4 inches below a fluorescent light fixture. I have mine on wooden shelves that are about 5 feet high so I can get lots in my French door window!
Also avoid a location directly adjacent to a heat source, which can dry soil and stress plants. So not over heat vents or too close to wood stoves.
Overwintering herbs indoors can be so rewarding, just brushing the leaves of your rosemary plant on a cold winter day can elevate your mood and keep you going on those bleak days. So have fun creating your indoor winter garden!
Natural Bug Spray Recipe:
1 litre boiling water
2 cloves garlic, coarsely chopped
1 cayenne pepper, chopped or 1/4 tsp cayenne powder
1/4 tsp natural dish soap
Combine together overnight, then strain through a coffee filter. To use: mist on plant everyday for a week to rid the plant of aphids and spider mites. Repeat process as necessary.