Yard & Garden Brief

Herbs offer a great amount of versatility for the gardening enthusiast. While chiefly grown for culinary purposes in seasoning foods, herbs can be used in other capacities as well. Their oils and fragrances have long been factors in the manufacture of cosmetics, perfumes, dyes and potpourris. Their medicinal properties have also been used for centuries. And, with the growing interest in flower preservation, there is a strong demand for herbal materials in dried flower arrangements and related crafts.


Soil Properties: The vast majority of herbs demand a well drained soil with a pH range of 6.0-7.5 for successful growth. (Most soils in the metro area fall into this pH range.) Outdoors, avoid planting in heavy clay soils as well as areas which are notorious for standing water. Containers used for growing herbs should always have holes in the bottom for proper drainage. Also, avoid using soils which have a high nutrient content. These rich soils may actually prove detrimental to the plant's development by promoting rapid, lush growth which is weak in volatile oils, the herbs' important characteristic.

Light: Herbs, unless noted shade lovers, require at least 6-8 hours of direct sunlight in order to grow well. All day sun is even better. The more intense the light, the more the oils will develop within the glands of foliage and stems, creating stronger fragrances and seasonings. A southern or western exposure will meet the needs of most herbs, although some may do well in a very bright east-facing location. Indoors, it is crucial to give herbs the best light available. During winter, when days are shorter and typically darker, fluorescent lights may be necessary to maintain healthy plants. 10-12 hours of artificial light daily is adequate for most indoor grown herbs. Inadequate light will result in spindly,thin growth.

Purchasing Herbs: Plants may be purchased from local garden centers and nurseries beginning in early spring. Generally, these sources offer the more common herbs in six-packs or single pots. You'll also find vendors at local farmers' markets. Speciality mail order catalogues offer more variety of unusual herbs, but research your choices thoroughly. Northern gardeners have to be content with growing some herbs as annuals which would otherwise be grown as perennials in warmer regions of the county. Lemon verbena and sage are two such examples.

Propagation: It is important to check the specific propagation and planting requirements of each herb, because some methods work better with certain herbs than others. Typically, the herbs grown here as annuals are best propagated by seeds or softwood cuttings. Other methods are usually used for hardy perennial herbs. For example, lovage and chives are successfully propagated by division in spring.

Seeds may be started indoors under fluorescent lights during the late winter months. Lights should be set for 14-16 hours daily, placed approximately four to six inches above the seedlings and raised as they grow.

Transplant herbs outdoors once frost danger has passed and the soil has warmed and is firm enough to work. Space seedlings with the mature plant size in mind. Crowded conditions will result in tall, weak plants. It also encourages disease.

Watering: Keep garden bed plantings slightly moist between waterings. Water thoroughly by soaking the soil to a depth of approximately 6-8 inches to ensure that the root zone is receiving adequate moisture. Outdoors, container-grown herbs dry faster than those in beds, so must be watered more frequently. Indoors, water thoroughly when the soil feels dry a half inch or so below the surface, depending on pot size. Never allow the plants to wilt between waterings, but avoid constant soggy soil conditions. Constantly wet soil encourages root rots which are the most common problem of herbs grown indoors, especially during dark winter months.

Fertilizer: Fertilize sparingly; herbs are not heavy feeders. In most cases, garden beds can benefit from using a 5-10-5 commercial fertilizer at the rate of 3 ounces per every 10 feet of row. Apply once or twice throughout the growing season. Use a liquid fertilizer at half the label recommended strength once every 4-6 weeks or so for indoor plants and every 3-4 weeks for herbs in containers outdoors.

Mulching: Mulching materials such as straw, marsh hay and leaves provide good winter protection for hardy perennial herbs. Depending on the size of the plant, a mulch 2-5 inches thick will keep the temperatures around the plant more constant during the late fall and early spring, keeping winter damage to a minimum. Mulching can also be beneficial during hot, dry periods of the summer by helping maintain moisture in the soil.

Problems: In general, herbs do not have serious problems with insect pests and diseases. If using pesticides, choose only those insecticides and fungicides which are labeled for use on herbs. Aphids and other insects can be somewhat controlled with forceful sprays of water or with insecticidal soaps if they are a constant problem on edible herbs.

The most common problem with herbs, particularly those grown indoors, is root rot resulting from over watering and poor light conditions. The best precaution is to provide your plants with good soil drainage, bright light and decent air circulation.

Harvesting: Culinary herbs may be harvested throughout the growing season by snipping sprigs and leaves as they are needed. Many will contain the best flavor if harvested just before the flowers are beginning to open. By making the cut a few inches down the stem and just above a set of leaves, new growth will constantly be encouraged and a bushier plant will result. This is especially important with the annual herbs such as basil, which would otherwise become quite woody and less productive if it were left to go to seed.

Herbs grown for their flowers are harvested by picking a few stems or whole bunches just before the flowers are fully opened. And those grown for seed, such as caraway, are best collected late in the season when the seed is ripe.

Regardless of the method used, the time of day you harvest is very important. Mid-morning hours are best, as this is when oil content is highest. This is usually just after the dew has dried and before the heat of the day begins.

Once picked, herbs should be gathered quickly and kept out of bright light. Washing the herbs is not required but may be necessary if there is a lot of dirt or debris on the foliage. If this is the case, wash the herbs gently with warm water and pat them dry or use a hair dryer on a low setting. Otherwise, excess water will slow the drying process.

Methods of Preserving

airdry herbs
Hang stems upside down to airdry.
Air Drying: Gather 4 or 5 stems, and tie the ends together. Hang them upside down in a dark, warm, well ventilated room. Label them, using small tags, as dried herbs will look different than fresh and mix-ups can easily occur. The foliage should dry in 7-14 days depending on conditions. This method also works well for drying seed pods and collecting seeds. To collect seeds, simply place a paper bag around the hanging herb with holes in the side for air circulation. As the drying process begins, the pods will open, the seeds will drop out and collect on the bottom of the bag.

Air drying can also be done under the same conditions, using screen racks. Make sure the herbs are spread out only one layer deep. A cookie sheet or solid surface will not work as well, as only one surface will dry properly.

Oven Drying: Again, using a screen type tray, spread the herbs evenly and set the oven no higher than 100° F or at it's lowest temperature. Keep the door open and check every thirty seconds. The herbs will dry very quickly, within a minute to a minute and half.

Microwave: Microwave ovens provide the fastest means of drying herbs. But because of different wattages and models, specific settings would best be determined by experimenting with your own microwave. Start with using 15 second intervals and keep checking the herbs until they are thoroughly dried.

Freezing: Freeze small quantities of herbs at a time. A few leaves or sprigs placed in a labeled plastic bag works well. The material can also be chopped up and packed into ice cube tray compartments. Top it off with a little water and freeze. Avoid freezing large quantities as they can't be refrozen once thawed. Properly frozen herbs should be used within a year.

Storage: Once herbs are dried, strip the leaves from the stems. Do not keep stems as they tend to retain moisture long after the leaves have dried and may become moldy in storage. Store leaves whole if possible as the larger the piece, the better the flavor retention. Store the herbs in airtight containers. Herbs stored using these methods can usually last up to a year or year and a half. Keep stored herbs away from bright light and heat sources and check them periodically for any moisture buildup within the container.

Common name
* Shade tolerant
Latin name
A..Annual (As grown in Minnesota)
B..Biennial (As grown in Minnesota)
P..Perennial (As grown in Minnesota)
Angelica* Angelica archangelica B
Basil Ocimum basilicum A
Bee Balm Monarda didyma P
BorageBorago officinalis A
CarawayCarum carvi B
CatnipNepeta cataria A
Chervil* Anthriscus cerefoliumA
ChivesAllium schoenoprasum P
Common FennelFoeniculum vulgareA
DillAnethum graveolens A
Golden Marjoram*Origanum aureum A
Lemon Verbena Aloysia triphylla A
LovageLevisticum officinale P
Mint* Mentha sp.P
NasturtiumTropaeolum sp.A
OreganoOriganum heraocleaticumA
ParsleyPetroselinum crispumA
SageSalvia officinalisA
Summer SavorySatureja hortensisA
Sweet Marjoram Origanum majorana A
Sweet Woodruff* Galium odoratum P
Thyme Thymus sp.A

Reviewed 3/00

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Index to Yard & Garden Briefs

University of Minnesota Extension Service