When we think of harvest time, we usually conjure up visions of autumn, with its colorful leaves and bright orange pumpkins, bright red apples and crisp, cool air. Many plants mature during those months when the temperature begins to cool, signaling the approach of winter. In those parts of the world where winters include snow and ice and freezing temperatures, most plants have no choice but to spend their growing seasons preparing to perpetuate their species in one fashion or another. Either they prepare seeds with sufficient nutrients to allow them to grow, or they build up nutrient stores of their own in order to survive those cold, dark months. In either case, the product of their labors is also available for us to share. Herbs, though, may be harvested at various times throughout the year.
Herbs, which to me includes all those plants we find useful beyond their appearance, have many parts that provide benefit in one form or another. The bark, roots, twigs, leaves, flowers, stems, seeds or leaves may be sought after, depending on the effect desired. Different herbs and different parts of herbs may require different harvesting techniques and schedules.
There are some general rules about harvesting herbs, which may be somewhat modified, depending on the plant and the use to which it will be put. Most leaves are at their most potent just before a plant bursts into bloom. To ensure that they're at their full potential, you usually harvest them after that time of the morning when the dew has evaporated, and before the sun is at its full height. Bark is generally collected in springtime, right up until summer begins, but it's always a good idea to obtain a regional field guide to make sure you're collecting when the bark toxicity, if any exists, is at its lowest. Roots are usually collected in the fall, except for those of the dandelion, which are gathered in spring. For fall root collection, schedule a time between when the green parts die back and when the ground gets hard from the cold.
For thousands of years, various cultures have developed and followed complex rites to ensure that herbs were harvested at the time they would be most potent. For some centuries recently, those rites were discounted as being associated with magical traditions; however, they were extremely effective and easy for their users to remember. Fortunately, present day thinking about such practices is more open-minded and many are realizing that the traditions of millennia have strong practical benefits. Whether you follow the ritual procedures or not, there are many factors to prepare for and consider.
Since storing herbs for long periods of time can cause them to lose their potency, you may wish to consider which herbs you will be using soonest and which will maintain their qualities longest. If at all possible, make a calendar to indicate what you can gather and when, and arrange it to enable you to acquire those herbs you will need in time to have them, at their freshest, and not have to store them too long. Of course, there will be some that you cannot easily obtain at various times. You can store them and, in fact, most will keep up to twelve months with little deterioration if they are kept in a dark cool place, however, keep in mind that as they age, they may lose some of their potency. Inspect them frequently for signs of insects or mold. Note that the loss of color is a sign that herbs have been kept too long and in sub-optimal conditions. You can also consider supplementing your supplies with herbs bought from a reliable shop or specialist mail order supplier.
Then, you might have to make arrangements to gather herbs from some location other than your own back yard. If you wish to harvest plants from private property, naturally you must contact the owners first and obtain their permission. You should make sure that the property from which you gather herbs has not been exposed to chemicals in the form of fertilizers, pesticides, herbicides or pollutants. Many herbs grow wild on the sides of highways, but those will have been exposed to carbon monoxides and pollutants from car exhaust and would be unsuitable.
You will need to know which tools are best suited for collection of the various plant parts you seek and make sure you have those with you when you harvest. You'll also need containers to hold what you've gathered. I like to use paper lunch bags for dry plants. I write the names of the herbs I've collected on the outsides of the bags with a soft pencil. When collecting sap, you will need spill-proof containers. If some of your herbs will be used fresh, you may wish to place them in an airtight container. Most herbalists agree that plastic can react to oils in the herbs and so should be avoided. They generally prefer pottery or glass containers instead. If you use glass, be sure it's dark colored. Herbs lose their potency more quickly when exposed to sun after harvesting. Of course, you should always make sure that your hands, tools and collecting utensils are clean and dry.
Once you have collected all the plant parts you will need for a period of time, you'll have to prepare them for storage. Most herbs will be dried and, depending on the plant part in question, varying drying techniques can or should be used. Flowerheads, berries, root pieces, and bark can be dried on a flat paper-lined tray. Berries should be turned regularly during drying. Seeds or small flowerheads should be cut with 6-8 inch (15-20 cm) stems, tied together in small bunches and hung upside down to dry. They can be hung over a paper-lined tray to catch the seeds or flowerheads when they fall off the stems, or a paper bag can be tied over the bunch to serve the same purpose. Larger leaves, like those found on burdock, may be removed from the plant and dried individually. Aerial parts (stems and leaves) can also be tied together and hung upside down. The medicinal oils tend to concentrate at the lowest point, so leaves will be strongest this way. Herbs with high oil levels, e.g. catnip, lemon balm and mint, require extra care when drying them.
Where you dry your herbs is something else to consider. They should be dried in a dark, relatively cool place. The temperature should be between 70 and 90 degrees Fahrenheit, or 20 to 32 degrees Centigrade. There should be good air circulation, too. Attics may be acceptable if they don't get too hot, or an outdoor shed with a small fan running. Don't put herbs up to dry in a garage or any storage area where you keep motors like those on lawnmowers - the fumes from the chemicals may contaminate them. It's best not to dry them in a microwave oven as the microwave radiation may have a deleterious effect on the herbs' chemical makeup. You can dry herbs in your kitchen or another room of your house if you have an unused cabinet or a spot in a corner where it is dark and they will not be disturbed.
Once drying leaves have become brittle (it usually takes between 5 and 10 days) to the touch, remove from the stems by rubbing them onto a piece of paper and then pour them into a dark glass or ceramic container and seal tightly. Similar containers can be used to store sap from plants like aloe vera (scrape the gel from the inside of the leaves with a palette knife or the back of a spoon), greater celandine or wild lettuce (these can simply be squeezed over a bowl. If you do collect saps, which is done at the end of winter, just before the new leaf shoots open, you might want to keep in mind that some are corrosive, so protective gloves might come in handy.
The following list provides some suggestions for your herb collection calendar:
Evergreens, such as sage, rosemary and thyme
Lungwort or sweet violet stems and leaves (during flowering)
Coltsfoot, cowslip or elder flowers
Early to Midsummer:
Stems and leaves before flowering on plants like angelica, catnip, dandelion, dill, fennel, lemon balm, parsley, peppermint, sage, yellow dock
Flowers of borage, chamomile, honeysuckle and St. John's wort
Mid to Late Summer:
Stems and leaves during flowering of marjoram, meadowsweet, mugwort, melilot, skullcap, thyme, vervain, yarrow
Flowers from lavender, mullein or hops
Leaves of borage, coltsfoot, fenugreek and some others can be collected after flowering at this time
After leaves have wilted, collect the roots and bolts of angelica or burdock during their first year, black cohosh, cowslip, garlic, goldenseal, marshmallow, purple coneflower or valerian
Ripe seeds and fruit from bitter orange, celery, dill, elder, fennel, lovage
Finally, a word about conservation. If you are harvesting wild herbs, or even if you're harvesting your own, it wouldn't hurt to follow one ancient tradition that was no doubt created to ensure the continuity of our plant apothecary. The Cherokee are said to have fostered the tradition of finding three plants of a particular kind and not touching them, harvesting only from every fourth one found. Certainly, that will help to keep a healthy supply of these plants available in nature for our own future benefit. Some plants are protected by law; never pick any plants that are considered nearly extinct, such as ladies slipper, false unicorn root, wild American ginseng, some echinacea species, trillium, and wild goldenseal. Whether your interest in herbs is culinary or medicinal or both, it's always a good idea to maintain the respect for them that our ancestors had. So, enjoy the beautiful fall weather and Happy Harvesting!