As we enter the fall season our thoughts turn to saving the plants we can and knowing where to cut our losses. Many people who have been growing herbs, especially in containers, are wondering how to overwinter them for next year. On Facebook, they are asking questions such as: Will the herbs make it over the winter, should they be removed or cut back, can they be saved somehow for next year? To answer these questions, there are three things to consider.
Know the plant. Just like not all children or dogs or cats are the same, not all “herbs” are the same. “Herbs” is a catch all phrase for a useful plant but there are many different types. Learn if the plant is an annual, tender perennial or tropical, biennial, perennial, etc. This is objective information that is easy to find on the internet.
Know your zone. If it is an annual plant, it will not matter which hardiness zone you live in since its life cycle is one growing season. It will live, set seed, and die (but you may be able to save seeds). However, if you are growing tender perennials, tropicals, and perennials, it matters if you are in very cold winter place which has a lower zone number, or a mild winter place like Virginia, Zone 7, or even a warm winter area such as Florida, Zone 10. This is objective information that can be found on the internet or this link.
Know about insulation. Many plants will not overwinter if they are in a container because the container does not provide enough insulation. If the same plant were in the ground, it may do much better because the soil provides more insulation. If you are growing a perennial herb such as thyme in a container, you need to put it in the soil now in order for its roots to become established so it can survive the winter in the ground. Don’t forget to water after you transplant from a container to the garden bed as September and October can still have hot days.
Here are a few common herbs that I grow in my Virginia garden and how I deal with them in the fall.
Basil: By now basil has set seed and is finished for the season. Either save the seed or leave for the birds. The plant can be pulled anytime from now until we get our first frost, typically at the end of October. The frost will kill the plants and you will want to pull them out and compost as the cold will blacken the foliage. If you grew this in a container, it will not matter if you move it to the ground as it is an annual that will die in October.
Cilantro: If you had grown cilantro in the spring, either in a container or in the ground, it should have gone to seed by now and you can save the seeds for next year. The plant itself will die or is dying. You can sow cilantro seeds again in the fall with the cool weather but remember to water as the days are still hot. You can sow in a container or in the ground in the fall but the winter will kill the plants either way. It likes the cool weather and you may have enough time to get cilantro for the kitchen now but the plant will not survive our winters.
Calendula: By now this plant may look awful because it does not like the summer heat and tends to get powdery mildew on the foliage. It does not matter if it is a container or in the ground, the winter will kill it. You can save the seeds for next year. By late September, I pull mine out because it is ugly with powdery mildew and will not survive the winter and I would rather plant cool season pretty flowers like pansies. I do sow calendula seed again next spring.
Dill: Dill should have set seed by now, which you can save. Dill is a short-lived annual plant that usually sets seeds in mid-summer and then gradually dies by fall. You can pull the plant anytime and sow seeds again next year. If you had it in a container there is no need to move to the ground as it is an annual that should be dying now.
Tender Perennial and Tropical Herbs
Lemon grass and lemon verbena are not going to make it outside in the winter but you can harvest the lemon grass and freeze it or move the plant inside and let it go dormant. You can dry lemon verbena leaves for tea or potpourri, or you can bring the plant in the house and let it go dormant. They are not pretty when they are dormant, so you have to weigh the effort versus the cost of buying a new plant next year. Lemon grass is actually one of the cheapest plants to purchase if you buy the culm or shoot from an Asian grocery store and root it in soil. Lemon verbena has to be purchased as a small plant at a nursery and can be a little more expensive.
Ginger: There are different types of ginger but the one you think of when you purchase a dried root for cooking should be harvested soon. It will not make it over the winter here. I have another type called galangal which actually did overwinter in my garden but I think it was in an especially warm area that mimics a Zone 8. I had purchased it last year and grew it indoors over the winter. In May I potted it up and it grows very well in a large container. This type of ginger is happy as a houseplant so I will harvest what I have and pot up a small one to bring indoors now.
Turmeric: Tumeric should also be harvested soon, it will not overwinter here. I have tried to grow it in the garden bed to see if it would come back but it does not. Still, an cheap root to purchase at an Asian grocery store, just pot it up and it will grow.
Fennel: There are two kinds of fennel: bulbing and what they call leaf or foliage fennel. In my garden, the bulbing fennel is an annual where you harvest or pull the plant, bulb and all, so by now you should have harvested it. It will not overwinter. The leaf fennel is marginally hardy which means is really hardy to zone 8 but in our area, it may overwinter depending on the mildness of the winter and the microclimate where it is growing in your garden. Mine are in a full sun, warm spot so mine overwinter well. They can get very large in the summer and in the fall, they set seed. You can collect the seed to sow next year, leave the plant as is in the garden and see if it will overwinter, or cut back and see if the remaining stump or root will overwinter and come back. If you grew this in a container, you can try to move to the ground now and see if it will overwinter but very easy to grow from seed.
Pineapple sage: Pineapple sage comes into its glory in the fall when it blooms red flowers. This plant is also marginally hardy. Sometimes it comes back next year and sometimes it does not, depending on the winter. It is best to purchase this in the summer when you see it for sale at the nursery because by the time you want it in the fall, it may not be available anymore. Pineapple sage will die back in the winter so need to prune or cut back after our first frost to clean up. You can leave in the ground to see if it will come back. I had one that came back for a few years and then it died so I just bought more. If you grew this in a container it should be blooming now so you don’t want to move it or you may lose the blossoms.
Anise hyssop: Anise hyssop has vertical blooms that attract butterflies and bees. It blooms from summer to fall and in the fall, you can cut the flower heads and save the seeds. In the winter, the plant will die back. It comes back in the spring with purple foliage that gradually turns to green when it matures in the summer. This is a hardy perennial but short lived. If you grew it in a container, you can move it to the ground or collect the seed and sprinkle in the ground and you will probably get anise hyssop babies in the spring.
Oregano, marjoram: Mine are in the garden bed and by now these have set seed and look weedy and overgrown. You can leave as is, cut back the flowering stalks only, or give it a trim to leave a few inches. I personally leave my flower stalks which have seeds for the birds. In March I cut them back down to where I am seeing new growth at the base. No need to save seeds, this is a perennial plant that will come back every spring. If you have this in a container, move it to the garden bed now and water until established. The marjoram is marginally hardy but the oregano is very hardy. In my garden my marjoram overwinters well since it is a full sun, well-drained area.
Sage, rosemary, lavender: These are woody shrubs that will over winter in my zone 7 area provided the soil has good drainage. If they are in a wet spot, they may get root rot. If you have these in a container now, move them to the garden bed for insulation. Keep in full sun and do not forget to water so the roots can become established before winter. I do not prune the sage back. I leave the lavender wands on the lavender over the winter because they add vertical interest. In the spring, I cut a few inches below the wands to prune the lavender wands off but also to give the plants a little trim (they are getting huge now). There are other people who like to cut off the lavender wands now to “clean up” and either way is fine. My rosemary plant is too big, so I prune it back a good 6 inches every spring. Rosemary is a plant that can be harvested year-round for cooking or crafts.
Chives: Chives are perennial plants–very easy to grow. The foliage dies down in the fall and comes back in March. No need to cut it back or do anything. If you want to save the foliage to use for cooking before it dies down, you can give it a buzz cut from now until October and freeze the foliage or preserve in a butter. If this is in a container, move to the garden bed.
Thyme: Thyme plants make great groundcovers. These are hardy perennials that remain above ground in the winter. No need to prune or cut back unless you think it is spreading too much. If this is in a container, move to the garden bed.
Mint: Mint should always be grown in containers. Fortunately, they are hardy so they will make it through the winter in the container. By now many of my mints have set seed and are straggly. I cut them back to tidy them and pull weeds that have taken hold in the containers. Mint is easy to propagate by cuttings or divisions so no need to save seed.
Lemon balm: People often complain that their lemon balm is too assertive, but mine in my garden bed has not moved. This plant will die down in the winter and come back in the spring. By now the flower stems are bare and straggly and I may cut those off to clean up but there is no need to cut the plant itself or the foliage. And no need to save seed as it is very easy to propagate by division. Again, if this is in a container move to the garden bed but if you think it will be too rambunctious, just let it die and buy a new plant next year.
Parsley: If you have parsley in a container, you may have to leave as is and let it die because it does not like to be transplanted. If you have it in a garden bed, leave as is. It may stay above ground and green all winter long if we have a mild winter. If it has flowered and set seed, save the seed. This plant grows the first year and then flowers and sets seed the next year. So any plant that is flowering and setting seed is in its second year of growth and will die this year. If you want, you can harvest the seed and then pull or remove those plants.
If you have any herb questions, please comment and I will respond. Or join the Culinary Herbs and Spices Facebook group and others will respond as well.