Herb Gardening 101

Herb GardeningHow to grow healthy, delicious herbs in your garden and indoors.

Herbs have long been revered for both their medicinal and culinary value. They may cure colds, help you sleep and add flavor and zest to dinner. Fortunately for home gardeners, growing herbs is relatively easy. They thrive in just about any type of soil, do not require much fertilizer, and are not often bothered by insect or disease pests.

Defined as a plant without a woody stem that dies back at the end of each growing season, herbs were once considered a gift of the gods. Elaborate ceremonies and rituals celebrated their growth, harvest and use. Today, herbs are popular in many home gardens, where their leaves are utilized for flavoring and an entire plant may be used for medicinal purposes.

Getting Started

An herb garden can be grown outside or inside depending on your needs, climate and space. There are advantages and disadvantages to both.

Indoor Advantages
Outdoor Advantages
Easy to access Higher yields
No weeding More flavorful
Year round growing season More space

Whether you choose to grow inside or out, all herbs need plenty of sunlight, moderate temperatures, and a soil or potting mix that drains well. Keep in mind that most herbs are native to the Mediterranean — provide them with conditions similar to this region and they will flourish. Of course, you can combine the two by growing in containers. This way herbs can be outside during the growing season and moved indoors when it gets cold.

Indoor Gardens

Location is the most important choice you’ll make in setting up an indoor herb garden. Herbs need at least 6 hours of bright sunlight, which may be tough to get during the winter months. To ensure plants are getting plenty of light consider the following:

  1. Southwest facing windowsills offer the most light.
  2. A corner with two windows (one facing south and the other west) is ideal.
  3. Supplement with HID grow lights if your home doesn’t get enough natural light.

Growing medium is a better choice than garden soil for your potted herbs. Choose an organic growing medium that is loose and drains well. You can purchase a commercial mix or make your own:

Soil Mix – Use equal parts compost, sterile topsoil and builder’s sand. An all-purpose organic fertilizer can be added to this mix.

Soilless Mix – Combine 4-6 parts peat moss, 1 part perlite and 1 part vermiculite. If adding nutrients, blend 1/2 cup each bone meal, oystershell lime (raises pH) and cottonseed meal/canola meal per 8 gallons of potting mix.

Water your plants enough to keep the soil moist without over-watering (roots will rot in a soggy container). Let the top of the soil, or growing medium, dry out completely between waterings and check moisture levels often. A soil moisture meter can help eliminate over and under watering by measuring moisture at the root level. It’s also a good idea to plant herbs in separate containers, or make sure that plants grown together have similar watering needs.

Tip: Mint, parsley and lovage do best in fairly moist soil, whereas rosemary, thyme and sage prefer soil that is only slightly moist.

Seeds of annual herbs (basil, coriander, dill and oregano) can be started indoors and grown year round. Place a collection of popular culinary herbs in a sunny kitchen window and they’ll be available when needed. Perennial herbs, like chives, parsley, sage, sweet marjoram and thyme, can be started from seed, but it is often easier to purchase young plants from a nursery. Because perennials grow for more than one season, it’s best to keep them outside in pots during the summer and bring them in before the first frost.

Outdoor Gardens

Location is just as important for outdoor-grown herbs as indoor-grown. Figure out how much space each herb will need (read the seed packet or planting instructions) and how many plants you want to grow. Then calculate how much room you’ll need for your garden. Also, choose a location that provides adequate amounts of sunshine. Many herbs require 6-8 hours of sun each day to produce the essential oils that give them their pleasant taste and scent.

Soil will vary from area to area, but there are some specifics that all herbs need. Select a garden site with a well-drained loam soil, or improve the soil with the addition of aged animal manures, compost or peat moss. Quality soil should drain well, yet retain both moisture and nutrients. Also, use a soil test kit to test different areas in your garden. Soil pH affects nutrient availability to plants and can be adjusted by mixing oyster shell lime (raises pH) or elemental sulfur (lowers pH) into the soil. A slightly acidic to neutral soil (pH between 6.0-7.0) is best for the majority of herbs. If the soil in your area is really bad consider raised bed gardening. Filled with your own growing mix, a raised-box herb garden allows you to bypass poor soil altogether.

Prepare planting beds by digging 10-12 inches into the soil and turning it over. Get rid of any large stones. Then, mix in plenty of organic matter. Use a rake to level off the ground when you are done..

Water enough to keep the soil moist, but not soggy and avoid frequent light waterings which can draw roots to the soil surface. An occasional soaking is often better for plants. However, you do not want to wait so long between watering that herbs wilt or become stressed.

Tip: Group plants that have similar watering needs together and your herb garden will thrive.

Planting and Propagation

Many herbs can be started from seed, but there are a few (including rosemary, oregano and mint) that will take better to propagation by cuttings or being transplanted. Decide what herbs you wish to grow and read up to find out how they are best planted (see Plant Propagation 101).

Start Seeds Inside

If you know what you are doing seed starting can be pretty easy:

  • Select containers. You can use seed trays or peat pots. You can also use egg cartons, yogurt containers or make your own pots from newspaper.
  • Choose a high quality potting soil.
  • Fill containers with potting soil and water. Don’t let the soil get soppy, just evenly moist.
  • Place the seeds on top and cover with a tiny bit of soil. Very small seeds can lie directly on the surface without being covered. Check your seed packet for specific planting guidelines.
  • Place pots in a south-facing window where the temperature stays between 60-75° F. A seedling heat mat can help keep your young plants warm.
  • Read Ten Seeds Starting Tips to learn how a practiced propagator gets seedlings off to a healthy start.

Transplanting

After 5-10 weeks, your seedlings will be ready to move outside. But, don’t just throw them out there and let them fend for themselves!

  • Wait until the last danger of frost has passed and harden them off. To harden plants, leave them outside in the shade for progressively longer amounts of time each day. Start with a couple of hours and gradually work up to a full day and then overnight.
  • Water plants an hour or two before transplanting.
  • Transplant your herbs on an overcast day if possible, or in the evening to reduce shock.
  • Prepare your beds before transplanting so that the move is quick.
  • Loosen the herbs from the sides of their pots and gently rest them in a small hole in the ground. The plant’s base should be even with the ground.
  • Fill the rest of the hole and gently tamp down the ground.
  • Water.

Direct Seeding

  • Seed your herb garden after the danger of frost has passed.
  • Read the seed packets to determine depth of planting.
  • Prepare a trench to place the seeds at the correct depth. You can use your hands or a trowel for this.
  • Scatter the seeds at the recommended spacing. It’s better to plant too many seeds than too few — you can always thin the plants later.
  • Cover seeds with a little soil. If you have a lot of clay in the garden, consider covering the seeds with vermiculite. Since clay absorbs heat from the sun, there is the possibility of your seeds getting burnt.
  • Water gently.

Propagation by Division

By dividing existing plants, you can get new plants for free.

  • Divide plants in early spring before they start growing.
  • Use a spade to cut the roots. For smaller plants you may be able to pull the roots apart with your hands.
  • Add plenty of compost when replanting your divided plant into it’s new home.
  • Keep the soil moist – not sopping wet — until the new plant becomes established.
  • Chives, French tarragon and mint do well when propagated by division.

Maintenance

Once your herb garden is established you’ll need to do a little maintenance to keep it flourishing (see Caring for Your Herb Garden). Herbs are generally pretty hardy, in fact many produce oils and chemicals that naturally repel pests. Some herbs, like sage and rosemary, seem to like harsh conditions that other plants eschew.

Occasionally, your plants may get attacked by insects, molds, mildews or other undesirables. Visit our Pest Problem Solver for descriptions of common pest problems and a list of organic remedies.

Fertilizing

Your outside herb garden may not need much fertilizer — although it never hurts to throw some organic nutrients in your plants’ direction — but herbs grown in containers will require a bit of extra care.

Even if your growing media is perfect from the start, container grown plants continuously use up nutrients as they grow. They are also leached out from the potting mix every time you water — and you’ll be watering more often because potted plants dry out faster than their backyard counterparts growing in open soil.

To ensure the health of your container grown plants, mix a time-release organic fertilizer into the soil prior to planting. During the growing season, it’s also a good idea to add liquid fertilizer — fish emulsion works great — at about 1/2 the recommended strength, especially if you find your plants a little tired looking or their color fading.

Tip: Do not over-fertilize herbs. Too much of a good thing will produce bigger plants, but the essential oils that give them their flavor and aroma will be diluted.

Winterizing the Garden

If you live in a climate with cold winters, it’s likely your plants won’t make it through the season unless properly protected. Most herbs have shallow root systems that are easily damaged by freezing temperatures. To ensure their survival, make sure plants are healthy going into winter and do not fertilize or prune late in the growing season. This encourages plants to grow and what you want them to do is slow down. Plus, leaves help insulate the plant — so leave them on there!

A 4-inch layer of mulch will help keep plants warm when temperatures turn cold. Once the ground has frozen, spread a loose organic mulch (oak leaves, straw, evergreen boughs, etc.) around the base of each plant. Mulches that pack down or get mushy can promote rot and should not be used. Remove mulch only after you see new growth in the spring.

Finally, some herbs, like Greek oregano, lemon verbena and rosemary, are very sensitive to cold. Despite your best efforts they are unlikely to make it through a winter. Dig up plants like these and replant them in containers. Herbs in containers can be brought in the house and then replanted in the yard in the spring (see Overwintering Plants Indoors).

Harvesting and Storage

Harvesting herbs is easy! Basically, you snip off what you want and that’s it. The trick, however, is knowing when to harvest, which is dependent on the type of herbs you are growing and what you are growing them for.

Harvesting

  • If it’s the leaves you want (mint, basil, etc.) harvest them before the plant flowers. Early morning is the best time of day to pick leaves – after the dew dries, but before the heat sets in. Avoid washing leaves as this strips them of their aromatic oils.
  • Harvest flowering herbs (chamomile, borage, lavender) before the flowers are fully open.
  • Herbs grown for seeds (caraway, coriander, fennel, dill) can be harvested when seedpods change color.
  • If it is the roots you’re after (goldenseal, ginsing), dig them up at the end of summer or early autumn.
  • Many herbs (basil, mint, chives, oregano, parsley) grow better with consistent pruning and harvesting.
  • Perennials can be cut back to half their height without problems.
  • Stop harvesting and pruning perennials (hyssop, comfrey, lavender, mint, sage, thyme) by September, but annuals (basil, borage, chervil, coriander, dill, savory) can be harvested until the first frost.

Storing

Most herbs taste best freshly picked. This is because, volatile oils, the stuff that gives herbs their distinctive flavor, is fragile and breaks down quickly. If possible wait to harvest until right before you need them.

Short Term Storage

If you must pick your herbs before use, there are a couple of ways to keep them for a short period of time (see Selecting, Storing and Using Fresh Herbs – PDF). Remember, their flavor and aroma deteriorate quickly, so minimize storage.

Cilantro, parsley, basil and other long stem herbs can be stored in a glass of water. Trim their stems and place them in some water as if they were cut flowers. Other herbs (such as thyme, rosemary and chives) can handle a week or so in the fridge. Using a damp paper towel, wrap the herb loosely. Put them in a perforated — or open — plastic bag and place in the vegetable bin.

Long Term Storage

Drying

For the best flavor retention, drying herbs is the way to go (see How to Dry Fresh Herbs). While best if used within a year, dried herbs can be kept for 2-3 years.

For low-moisture, sturdy herbs (thyme, savory, dill, parsley, rosemary, sage):

  1. Cut whole branches.
  2. Rinse gently in cool water.
  3. Hang upside down in small bunches. A dark, dust-free, well-ventilated room is best for drying herbs.
  4. In 2-3 weeks, remove the leaves and place in an air-tight container.
  5. Grind or crush before use.

For herbs with tender, large leaves and a high moisture content (basil, lemon balm, tarragon, lemon verbena, lovage, mint, bay leaf):

  1. Remove the best leaves.
  2. Place them in a single layer on a drying rack — a window screen or any frame covered with netting will work.
  3. Hang the drying rack in the shade or a room with good ventilation. Air should be able to circulate above and below the rack. Do not put the rack in the sun — the herbs will lose too much flavor.
  4. During the first few days, turn the leaves.
  5. Once they are dry (about 1 week) store in air-tight containers.

Note: If leaves turn black or develop mold, discard the whole batch.

Freezing

Freezing is an easy way to store herbs for later use. It is relatively quick, and, in most cases, retains the flavor and the color of the herb. Herbs that freeze well, include thyme, chives, tarragon, borage, basil, dill, mint, lemongrass, savory, sage, and oregano.

To freeze herbs:

  1. Wash herbs and pat dry.
  2. Spread into a single layer and place on a cookie sheet.
  3. Put the cookie sheet in the freezer.
  4. After the leaves have frozen, move the herbs into an air-tight container and keep in the freezer until you are ready to use them.
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