The fragrances and flavours of herbs derive from oils that slow water loss and make them hardy enough to grow inside during the winter. Here are some tips about how to keep fresh herbs alive over winter and how to dry herbs too!
- Dig up herbs before the first frost and plant them in fresh soil, allowing for a couple of inches around the root ball. Check for insects which, if present, can be eradicated with a soap spray.
- Choose hardy plants to bring inside. Transplant them to containers that are deep enough for roots and that have drainage holes.
- Keep the potted herbs outdoors, but out of direct sunlight, for a week. This will condition them for less sunlight and acclimate them to the containers.
- Maintain five hours of direct sunlight daily to keep the herbs fresh. Turn them on a windowsill for even light, or expose them to fluorescent lights hung six inches above the herbs for 14 hours per day. Don’t let the leaves touch the cold window glass during winter, which could inhibit survival.
- Group your herbs closely to create humidity. Set your pots on a layer of gravel to ensure cool moisture without waterlogging the plants. Use liquid plant food at half strength to boost their health.
- Winter-kept herbs only need to be watered once or twice a week, usually in the morning. Don’t let the soil dry completely.
- Harvest your herbs in small quantities, leaving at least two growth points for new shoots to encourage density. Enjoy your fresh herbs all winter long.
How to Dry Herbs
Even if you bring your herbs indoors over winter there may be occasions when it is also useful to have some dried herbs on hand. The peak time to dry herbs is before flowering when the flavourful, aromatic oil content is at its highest.