As many people move toward supporting their health, herbal plants grow more and more popular. Farmers and gardeners, in turn, can leverage a great opportunity to provide an incredibly abundant resource to their communities by growing plants that have therapeutic properties.
Although many herbs are quite easy to grow, timing the harvest just right can be a bit tricky. And a lot of post-harvest tasks need close attention in order to preserve the potency of the medicinal compounds present in these incredible plants.
Why It Matters
Finding the best time to harvest an herbal plant is all about trying to capture the most abundant amounts of the compounds, called phytochemicals or herbal constituents, which are present in herbs.
It’s good to keep things flexible. There are no hard and fast rules, but following some helpful guidelines will help you capture the peak potency of a plant that will translate into vibrant herbal remedies.
Learn as You Go
There are so many varieties of herbal plants, all with very different characteristics. And each one may be a bit different in the harvest timing and technique. Beyond that, various segments of the plant may be used differently in traditional healing methods, such as the leaf, roots, blossoms or even the entire plant.
Every plant will have its unique growing patterns and life cycles that will affect the time of harvest. Folk tradition and herbal farming techniques provide a good foundation. But never underestimate the value of simply observing and interacting with plants and learning as you go.
Harvesting Leaves & Aerial Parts
Many leaves can be harvested throughout the growing season as needed, for recipes and remedies. This is especially true for culinary herbs and aromatic tea plants.
Common kitchen herbs such as lemon balm, peppermint, thyme, oregano and sage can be harvested a little at a time whenever you may want to make some broth (or when someone has a sore throat). Sometimes the best time to harvest may be when you are feeling inspired, or have a little extra time or vodka to make a tincture, syrup or some other fun herbal recipe.
Often the best time to harvest leafy, aromatic herbs is the morning or evening on a warm sunny day, preferably not after rain. The extra moisture can reduce the potency of some herbs and could potentially lead to mold issues in the drying process.
Abundant heat and a touch of drought can increase the aroma of some plants. You can gather certain herbs successively over time. And cutting down the flowering branches can extend their season before they go to seed.
Basil is a good example, where keeping the flowering stalks cut back can generate more leafy growth for a longer period of time.
Once the growing season winds to an end, or there is a seasonal transition in the life cycle of the plant, it can be helpful to cut back perennial plants almost entirely. Plants that get woody, such as lavender or oregano, benefit from harvesting the entire aerial (aboveground) portion of the plant.
Aerial parts often include the flower right along with the leaves, just as blossoms are coming on or forming in the plant. This often represents the height of the aromatic compounds or other healing phytochemicals in the plant. This can happen in spring, summer or fall depending on their particular life cycle.
When a grower desires the flower plant part, harvesting may take place over a period of a few weeks or months. Naturally, harvesting usually occurs as the plant begins to set flowers.
Morning is a great time for gathering blossoms, as some tend to close as the sun sets and the day ends. Most plants flower in succession, so not all blossoms will be ready at once. You will often observe unique flowering cycles with blossoms appearing on different stalks or branches at different rates, even on the same plant.
It’s nice to try to share the blossoms with the pollinators or tune in to when pollinators might visit flowers. You can harvest some blossoms (herbs such as chamomile or calendula, for example) by hand or with a small raking tool such as a blueberry picker. Others, such as lavender, you will need to cut at the stem and in different ways depending on future usage.
Some flowering herbs, such as sage or rosemary, you can gathered right along with the leaves to later mix together for herbal tea or other remedies. If flowers feel a bit sticky and resinous, consider this a sign of their potency.
For aromatic seed plants such as coriander and fennel, it can be a little tricky to catch the seeds when they are ripe enough, fully formed and at the height of their aromatic possibilities–but before they start falling off.
A lot of herbal seeds come from the Apiaceae or “umbel” family. Pollinators love the blossoms of these aromatic plants, and they’re usually quite easy to grow. When they reach the end of their natural cycle of flowering and fruiting, you can gather the seeds to be enjoyed later or replanted.
It’s possible to capture the seeds as they ripen and fall by putting a paper or mesh bag over the seed heads as they ripen. To share the blossoms with the pollinators, wait until the flowers begin to dry up a bit before putting the bags on. A good way to check if they are almost ready is to simply taste and feel the seeds and see if they are fully formed and aromatic.
With some medicinal seed heads, optimal harvesting goals will be entirely different, such as milky oat tops, where you are actually trying to catch them in a specific stage before they are fully formed and are still juicy with a milky white latex.
Root harvests traditionally occur toward the end of fall or very early spring, as the plant either goes dormant or comes back to life. It has been said that some roots will possess different energetic qualities depending on the seasonal pattern when harvested.
For example, some would say fall dandelion roots would be more moistening and spring roots would be more drying. There is certainly a lot to say about learning folk tradition regarding harvest times for roots of herbs, as they’ll all be a little different.
A lot of herbal roots are usually grown for a few years in a row, and it may take several seasons to establish a good root crop. Some roots you may harvest entirely, taking the life of the plant. Other roots you can harvest while leaving some in the soil to continue to grow.
Harvesting your own herbs for health and healing is such a rewarding experience. Taking a few extra steps to match peak potency with the time of harvest will help you create effective medicinal recipes from garden herbs.
Learning a bit about herbal life cycles, which part of the plant to harvest, how to prepare, dry and/or mix herbs may take a little time. But it is worth the end result.
Many herbal plants are perennial, and you get to know their patterns year after year. Exactly when they flower, when they go to seed or when they go dormant will vary a little in each location. Tasting, smelling and observing closely will give you clues to when the time seems right.
By following along with the patterns of nature and plant cycles, you will gain a satisfying and fruitful harvesting journey.
Know Your Herbs
While most herbs share a common love for well-drained soil and full sun, they have varying preferences and requirements. Below you’ll find a list of common herbs, along with brief growing notes that may prove helpful when planting.
- Basil: rich, well-drained soil; full sun
- Bee Balm: average, well-drained soil; full sun
- Borage: less fertile, dry soil; full sun
- Calendula: rich, well-drained loam; full sun
- Chamomile: well-drained, moist soil;
full sun to part shade
- Cilantro: well-drained, fairly rich soil;
- Comfrey: average soil; full sun
- Echinacea: average, well-drained soil, only water during severe drought; full sun
- Hyssop: ordinary soil (rich soil will produce luxurious growth, but less flavor and aroma); partial shade
- Nasturtium: ordinary garden soil; rich soils makes for few blooms; full sun or partial shade
- Lavender: dry, well-drained soil; full sun
- Lovage: rich, well-drained soil; full sun to part shade
- Mint: moist, rich, well-drained soil; prefers partial shade but will grow in full sun
- Oregano: dry, well-drained, alkaline soil, not too rich; full sun
- Parsley: moderately rich, well-drained soil; full sun to partial shade
- Pineapple Sage: light, sandy,
well-drained soil; full sun
- Rosemary: alkaline, well-drained soil;
full sun to partial shade
- Sage: light, sandy, well-drained soil;
full sun to light shade
- Summer Savory: dry, sandy soil,
with added organic matter; full sun
- Thyme: poor, well-drained, rocky, alkaline soil; full sun (rich soil makes less flavorful leaves)
- Yarrow: average, well-drained soil; tolerates poor soil and drought; full sun
– Jan Berry
This article originally appeared in the May/June 2022 issue of Hobby Farms magazine.