The herb-gardening season is drawing to a close. Twilight settles in earlier every evening, and the sun’s rays are shorter and cooler. This blazing summer brought its woes and its wonders, as always. The grasshoppers chomped unhindered by the biological control I spread about to keep their numbers down, and heat-loving weeds put up a fiercer fight than usual. On the up side, the lady’s-mantle was never more beautiful, and my new Echinacea purpurea ‘Kim’s Knee High’, a true dwarf, proved as tough and beautiful as its taller cousins.
Now, however, my herbs and I feel weary. The heavy chores—digging, hauling, turning compost, countless forays from nursery to garden—are finished. The herbs shot up, bloomed, and now give way to tired, blotchy leaves and drying seed heads.
For me, work remains to be done, but autumn’s chores can be done at a more leisurely pace than spring’s. Like the herb garden itself, garden work tapers off in autumn, when the garden gets ready for a long, peaceful winter nap, and I get a rest.
Know your frost date
Frost happens! Be prepared by knowing the average frost date for your area and attending to reports of the cold fronts that will further slow your herb garden. Although the frost date gives only a historical average date of killing frosts, knowing it gives you a working timeframe for tucking in your garden. If you don’t know your area’s frost date, call your county’s Cooperative Extension Service for the information, as it varies quite a bit from one locale to another.
First steps toward winter
Help your herbs grow sleepy by ceasing fertilization and tapering off watering, both of which encourage growth. Water less and less over a period of three or four weeks, unless an unseasonably hot autumn has set in. In that case, extend minimal watering until cooler weather resumes. Without supplemental water and feedings, the herbs will follow their natural course toward rest as they stop expending energy to produce new growth that the forthcoming cold weather will subvert. Herbs store their energy in their roots and crown during autumn, preparing for winter dormancy so they’ll be ready for spring. Let them do it without interference.
Have you let your herbs set seed? Some herbs, such as catmint (Nepeta fasenjii) and fennel (Foeniculum vulgare) can become garden pests if their seedy bounty spreads through the garden. Remove the seed heads and hoe any unwanted herb or weed seedlings that appear in autumn. If they get established and survive the winter, they will be unpleasantly hardy and aggressive in the spring.
You may want to gather the seed of herbs such as perennial dianthus, poppy, and purple coneflower and annuals such as nasturtium. Place the dry seeds in labeled paper envelopes and store them in a covered glass jar in the refrigerator. With a little care, these seeds will leap to life in the spring.
As a first step to bringing your container herbs indoors for the winter, isolate them and examine them for pests daily for a week or more.
Bargain herbs, anyone?
Save money and time by taking a stroll through your favorite nurseries, searching for the last few herbs and leftover bags of soil amendments such as compost. Snap up the last couple of sages, a stray hardy geranium, perhaps a little pot of garlic chives—selecting only herbs that are winter-hardy in your area.
This time of year, you don’t need to consult your garden plan for these little newcomers. Promptly plant your inexpensive little herbs in a sheltered garden spot, and, to establish their roots, give them plenty of water for a few weeks before tapering irrigation. Most will survive the winter in their impromptu home, and you can move them to permanent quarters in the spring. Perennials can be planted any time the ground is not frozen, but planting prior to frost date (even right up to it) gives the roots a chance to get established before cold weather sets in.
Make one job out of two by spreading your new soil amendments between the herbs, up to a couple of inches deep. The compost helps protect the herbs’ crowns and roots—the most vital parts of the plant. In the spring, work the compost into the first few inches of soil, where it aerates the soil and helps herb roots grow strong.
Bring in container herbs
Tender herbs such as bay laurel, scented geraniums, and lemon verbena can spend their winters indoors in containers. Take caution, however, as all outdoor plants are subject to hitchhiking pests such as aphids, white flies, spider mites, and so on. As a first step to bringing your container herbs indoors, isolate them from other plants, both indoors and out, and examine them daily for a week or more, looking for pests. Take the plants to their sunny indoor home if you find no pests.
If you find bugs, however, treat accordingly with strong sprays of cold water and/or insecticidal soaps such as Safer’s. If the pests persist, toss out the plant; it is better to lose an infested herb or two than gain a houseful of spider mites.
To prune or not to prune?
After a killing frost brakes herb growth, should you cut your herbs neatly to the ground, or is it best to wait? Well, yes and yes. Certainly pull out or cut off annual herbs, such as basil, nasturtiums, and calendula, to neaten the garden.
Among the perennial herbs, cut to the ground flower stalks on monarda, echinacea, lady’s-mantle, mullein, and the like, if you haven’t already, but don’t clear away the basal leaves. Some herbs form a low, late-summer rosette of new leaves that should not be disturbed; the leaves of others, such as lady’s-mantle, brown and crumple over the all-important crown of the plant, affording the herb protection.
Woody herbs, such as sage and roses, can be pruned, but only after they attain dormancy—that is, fall sound asleep in the January cold. These plants produce new growth on old wood, so prune only to remove obvious deadwood, excise nonproductive branches, and shape the plant.
Whether you prune a little or a lot, take care to remove all discarded plant material from the garden. It can harbor hidden diseases and pests, creating problems in the spring. If your herbs were healthy during the growing season and you see no change now, place the plant material in the compost bin. If not, discard it entirely.
A down comforter for herbs
Jack Frost will lay waste to annual herbs and nip the noses of perennial herbs, but without winter mulch, the herb garden’s down comforter, Old Man Winter can gleefully heave your herbs right out of the earth, leaving them to freeze and die. Winter mulch’s purpose is to smooth the peaks and valleys of winter soil temperature, protect herbs from drying winter winds, and conserve soil moisture.
Like a down comforter, you don’t need mulch until cold weather sets in for good. Mulching too early artificially preserves the soil’s warmth, weakening the herbs by prolonging their progress toward dormancy. If you add mulch too late, cold can damage the plants’ crowns and roots. In general, wait to apply mulch until the weather reaches the freezing point and stays cool or cold.
Many different organic materials can be used as mulch. Your favorite will probably be determined not only by effectiveness but also by availability of materials. In many areas, straw, dry leaves, or shredded bark are plentiful in autumn. Commercial shredded bark is fine; you can buy it in bulk from landscape firms or bagged from nurseries. If you have a good supply of raw material, home chipper/shredders do an adequate job but don’t shred as finely as the commercial operations do. In general, however, keep the following considerations in mind.
• Winter’s thaw cycle can deteriorate fine mulch (such as grass clippings) and expose herbs, so mix them with leaves and other types of mulch.
• To resist persistent wind, use a mulch with heavy pieces or use shredded bark, which mats into a fairly firm layer.
• Nonorganic mulches, such as plastic sheeting, can harm plants by reducing air flow and building up unhealthy concentrations of moisture and heat.
• Top off lightweight materials such as dried leaves with heavier bark pieces to keep the mulch in place.
The best winter mulch I’ve ever found is pine needles—but they’re not for every climate. The needles meet all of my qualifications of staying generally in place, protecting the herbs’ crowns, and persisting until spring. The best part, however, is the benefit the acidic needles make to my woefully alkaline soil. I turn the pine-needle remnants into the soil in spring (something that can’t be done with whole evergreen branches or bark pieces) and get excellent results. These mulches can protect and improve your garden at the same time, with minimal effort.
To mulch your garden, spread the mulch 4 to 5 inches deep and completely surround the plant crown; in very cold climates, herbs can be completely covered.
Winter itself takes the last step in your winter mulch, when fresh snow covers your herb garden. Snow stabilizes soil temperature, protects crowns and roots from drying winter winds, and adds moisture to the soil. It’s the perfect mulch; when you shovel the walks, throw the extra snow over the garden for the longest possible benefit.
The final cleanup
With your herbs snugly tucked in, only a few chores are left. Finishing them off will give you a satisfying sense of completion, and give you a head start on spring.
• First, have you ever measured your garden? If you haven’t, take a few minutes and do it now. Write down the measurements in a notebook and calculate the square feet of your herb garden. This figure will help you purchase and apply the correct amount of fertilizers, soil amendments, and plants, saving you money and frustration in the long run.
• Organize and tidy up your garden supplies. Arrange your tools and figure out ways to hang them or store them.
• Mark your calendar for winter watering. If you live in a dry, windy area, winter watering can make the difference between life and death for herbs as well as for shrubs and trees. A rule of thumb is to water liberally about once a month during winter thaws.
• Sort and inventory your garden supplies. Most herb gardeners have a stash of supplies that they tried and liked but forgot, or never liked in the first place. Set aside the supplies you will use, and ruthlessly get rid of the rest. With your supplies arrayed around you, record each and its quantity, using the book in which you recorded garden measurements. Take the book when you shop for spring garden supplies. You may find that you don’t need much, and when you do purchase more, you won’t buy a 10-pound bag when you actually need 5 pounds.
• Check your seed-starting equipment. If you like to start seeds inside under lights, check the light bulbs, electrical connections, and thermostats. Make necessary repairs and replace bulbs before spring is upon you.
Allow herbs to store energy in their roots and crown during autumn so they’ll be ready for spring.
The herb gardener’s winter rest
The herb gardener has two equally important winter tasks. One supports the body, the other is for the spirit.
Establish a winter stretching and exercise routine. Keep yourself limber and fit throughout the winter. It’s tempting to let the snow blow while you snuggle into an overstuffed chair with a good book and a cup of hot chocolate. That’s good, but also stretch every other day and walk, bend, and lift throughout the day. Go to a health club if it helps keep you on track. Keep moving. Remember how your muscles ached last spring?
Sign up for seed and plant catalogs. These wishbooks for herb gardeners bring an entire cornucopia of hopes and possibilities. Use the Internet or mail-in coupons in gardening magazines to make sure you get your favorites—they arrive during the worst snowstorm of January, it seems—as well as a few new ones. Arm yourself with sticky notes to mark your favorite pages, and make lists. Note the cultivation recommendations for your favorite plants. Compare varieties and costs of new herbs and old classics. And before you know it, it will be spring.
Doree N. Pitkin writes and gardens at her home in Greeley, Colorado. She is a master gardener and former assistant editor of The Herb Companion. She was also editor of The Big Book of Herbs (Interweave Press, 2000) and Herbs in Pots (Interweave Press, 1999).