Richters InfoSheet D9007
Growing Herbs from Seed
By Richters Staff
Starting Herbs from Seeds Indoors
Raising herbs from seeds is an excellent way to start a herb garden or expand an existing one. Although some herbs can be challenging to start from seeds, most of the popular herbs are easy from seeds.
Herbs are seeded directly in the garden or in containers. Container sowing gives you a jump on spring before it is safe to plant outdoors. Container sowing also allows better control over germination conditions, especially for expensive or slow-to-germinate varieties. If you plan to grow herbs indoors for year round fresh herbs then you need to start your herbs in containers. With sowing direct in the garden plants will grow where you plant the seeds, and, with proper thinning, there is no need for further transplanting. As a rough guideline the annual and biennial herbs are suited for either direct or container sowing, while slower germinating perennials are best started in containers.
Once started herbs are planted outdoors in the garden or potted up in containers for growing indoors or outdoors on decks, balconies or patios. Herbs in containers do not reach the sizes they normally attain in the garden. Because growth is more restrained in containers, care must be taken not to harvest too much at one time, particularly indoors during the slow growing winter season. Indoors herbs should be placed in your sunniest window or under fluorescent growlights positioned as close as possible to the plants and kept on 16 hours a day. Only herbs grown for their leaves are suited for indoor growing while herbs grown for their flowers, seeds or roots are not. Tender perennials too sensitive to withstand winter outside can be grown in the garden during the summer, but must be wintered indoors.
Containers and Growing Mixtures: Just about any sort of container will do. Cut-down milk cartons, yogourt containers, pots and trays are fine if they are clean and drainage holes are punched into the bottoms. The sowing medium should be loose, well draining, able to hold moisture, and be free of weeds, pests and diseases. Equal parts peatmoss, perlite and garden loam make a good mix. Sprinkle a little water over the mix and sterilize in an oven, at 80°C/180°F for 30 minutes. Sift through a 5mm/1/4" screen, or remove stones and soil clods by hand. If you do not make your own mix, use a good commercial seeding mixture.
Sowing: Fill the container with mix to within 1cm/l/2" of the top and firm it down. Mark off rows about 2.5cm/1" apart with a pencil, pressing 2-5mm/1/8-1/4" into the surface. Gently tap the opened seed packet so that seeds fall evenly in the furrows. It is better to sow thinly than to crowd. Cover seeds with soil to twice their diameter in depth and firm down. Fine seeds should not be buried, just firm into the soil instead. Water by soaking the container in a dish or sink filled with water to within 1cm/1/2" of the top of the container. Moisture will be drawn up by capillary action. Label the container and cover with wet newspaper to retain moisture, and place in a warm location (20-25°C/70-80°F) until germination begins. (Some herbs require cool or freezing temperatures initially to break seed dormancy.) Light is not necessary until seeds sprout. Lift the cover 1-2 hours daily to let fresh air reach the soil surface. If the surface shows signs of drying, water with a fine spray, taking care not to dislodge seeds. A misting nozzle works best. Keep the soil moist but not soaking wet.
After Germination: When seedlings appear, remove the newpaper cover and move containers to a cooler location (15-20°C/60-70°F) where they will receive good light but not too strong sunlight which can burn them. Turn the container daily to expose the seedlings to light equally on all sides.
A frequent problem at this stage is damping off: the sudden collapse of seedlings at the soil surface. It is caused by soil fungi and is aggravated by excess soil moisture, overcrowding of seedlings and low temperatures. The use of a sterilized sowing medium and clean, sterile containers helps prevent this malaise.
Transplanting: When seedlings have two sets of true leaves, they are ready to be thinned or transplanted. Some herbs that do not transplant successfully because they develop long tap roots should be thinned as you harvest starting when quite young. These include anise, borage, chervil, coriander, curled cress, cumin, dill, fennel nasturtium and parsley. Given a choice it is probably better to sow these varieties directly in the garden unless a fast start is important or if they are intended for indoor growing.
Most herbs can be transplanted to bigger containers to give their roots more room to develop. Use a richer soil mixture, e.g. two parts garden loam to one part perlite and one part peat moss. Gently lift seedlings out using a pencil to dig seedlings free and taking care not to damage the delicate root system. Separate seedlings and plant about 3cm/1-1/2" apart. Be sure seedlings are not planted any deeper or shallower than they were before. Label and water carefully without knocking over transplants. A seaweed extract added to the water helps reduce transplant shock.
As plants begin to grow, gradually expose to stronger light. Most herbs require a minimum 4-5 hours of direct sun daily. A sunny window is fine as long as the reflected heat is not too intense.
When the plants have grown enough to touch their neighbours, they are ready to be potted, or planted outdoors weather permitting. If you intend to transplant outdoors place plants outdoors in the shade for a few hours each day during the week prior to scheduled transplanting. This hardens the plants and minimizes the shock of transition from indoors to outside.
Starting Herbs from Seeds Outdoors
Site Selection and Preparation: Any well drained sunny site will please herbs. Generally herbs are not particular about soil type as long as it drains well. Poor soils tend to produce highly aromatic foliage, while richer soils produce less aromatic, but more abundant foliage. All soils will benefit from the addition of organic matter such as compost, manure or peatmoss, dug in to a depth of 20cm/8". Add sand too if your soil drains poorly. Cross rake the site to produce a smooth surface, removing all weeds, debris and stones.
Sowing: Mark off rows at least 25cm/12" apart. Gently tap the opened seed packet so that seeds fall evenly in the furrows. Avoid overcrowding. Small seeds can be mixed with sand for more even distribution. Cover seeds with soil to 3 times their diameter in depth and firm down to assure a good contact between seeds and soil. The tiniest seeds should not be buried, just pressed into the soil instead. Label rows, then water thoroughly with misting nozzle, taking care not to dislodge seeds. A cover of burlap will help prevent drying out between waterings. Keep evenly moist, but not soggy.
The alternative to row planting is broadcast seeding. This is a good seeding method if you want clumps or large plots of a single herb rather than rows of it. Scatter seeds over the prepared site evenly by hand or with a seeder. Then cover and water as described for row planting. When seeds are broadcast, it is not as easy to tell which seedlings are weeds and which are herbs.
When seedlings appear, remove the covering. After two pairs of true leaves develop, thin the crowded areas by pulling out the smaller, weaker seedlings. Many culinary herbs have flavour almost as soon as they sprout, so you can use the thinnings for seasoning. Remove weeds as they appear.
You can stretch the harvest season of some short-cycle herbs such as coriander and borage by making successive sowings several weeks apart.
We welcome your feedback on your experiences growing herbs from seeds. The information you provide will help us refine our recommendations to other herb enthusiasts. Please email your comments to Infosheet Feedback.
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