Growing an herb garden? Without a doubt, summer reigns, but many herbs can continue to thrive and grow well into the fall, too. The length of time your herbs will keep producing depends on the variety, climate, and conditions in your garden. While some are quick to remove over their herb garden in the fall while cleaning out the remains of other summer fruit and vegetable garden plants, many herbs can withstand cooler temperatures and keep on givin' for a while longer.
Warm-Weather vs. Cold-Hardy Herbs
Certain fresh herbs are better suited to warm weather, while others are more tolerant of cooler temperatures and will continue growing deeper into fall:
- Warm-Weather Herbs: Basil, cilantro, and dill are examples of herbs that thrive in the warmth but struggle once temperatures drop below 50°F. These common herbs will start to slow their growth and eventually die off as fall temperatures drop and time spent in partial shade increases.
- Cold-Hardy Herbs: Culinary herbs like parsley, thyme, rosemary, sage, and oregano are hardier and can withstand cooler fall temperatures. Many of these hardier herbs will keep growing until the first frost—and may even survive light frosts—with proper care.
How to Extend the Life of Your Favorite Herbs
As the season progresses, give your herbs some extra care:
- Protect them against cool weather and frost. Most herbs thrive when temperatures are between 60-75°F. Like most plants, cold soil temperatures slow new growth. Frost-sensitive herbs like basil will begin to wither and die once frost hits, while cold-hardy herbs merely pause growth for the season until a hard frost. During a mild winter, cold-tolerant herbs may continue to grow, but not as much as during the height of the growing season.
- Bring potted herbs indoors; make the most of a sunny windowsill. As the days get shorter in the fall, the reduced amount of sunlight will slow down the growth of your herbs. Most herbs need at least 6-8 hours of sun per day, but you can supplement natural light with a growing light if your herbs are planted in potted containers. I position our indoor herb garden in a south-facing window so the plants spend as much time as possible in the bright light, then turn on a grow bulb mid-afternoon until evening for extra care. (Put the light on a timer and you'll never forget.) While a grow light doesn't perform miracles, it helps, especially if you like to plant herb seeds like cilantro or basil all winter.
- Watering helps, especially if you're in a dry climate. Fall can bring cooler temperatures and drier air, so you'll want to make sure to maintain moist soil. Adding a slow-release fertilizer, compost, or a light layer of mulch around the base of the plants can also help.
- Ward off pests and diseases. As the season winds down, pests like aphids and spider mites may become more of an issue on a host plant. Cold weather can also invite diseases like powdery mildew. You can prevent too much plant loss by trimming dead or damaged leaves and using organic pest control methods. This applies to both garden beds, raised gardens, and indoor herb container gardens.
FAQ
Do row covers really help when temperatures drop?
Yes, for a period of time in the fall installing row covers or cloches can protect your herbs from early frosts and keep soil temperatures warmer. Just like greenhouses help plants early in the spring, the added layer can protect them from sudden cold snaps. We don't usually cover our hardy perennial herb plants, but I do get a few extra weeks of growth out of basil plants and other annual herb plants by sheltering them in the fall.
What should I do with herbs that are slowing down as the weather cools?
As fall progresses, some herbs may begin to slow down or stop growing. You have a few realistic options:
- Freeze or dry: You can harvest them and dry or freeze the leaves for later use.
- Oil infusions: If you have basil or other tender herbs, consider making herb-infused oils or vinegars to preserve their flavor before the cold season hits and damages the plants.
- Pruning and mulch: For perennial herbs like rosemary and thyme, simply pruning them back and covering the roots with mulch can help them come back strong the next year.
Does harvesting herbs promote growth?
Sure does! Regularly harvesting and trimming your herbs encourages the plant to grow, producing more shoots and leaves. Continue to help them flourish in the fall by continuing to use the herbs, but as Amy Enfield, Ph.D., Senior Horticulturist at ScottsMiracle-Gro points out, once your herbs stop actively producing new leaves, harvests should also stop for the health of the plant.
