Seed Starting Basics
Seed gardening is the most rewarding type of gardening!
To take a small, dormant capsule of life and unlock its culinary and/or aesthetic potential is glorious indeed!
There are few gardening experiences as rewarding as gardening from seed. If you’re a novice gardener and you’re wondering whether you need to start your seeds indoors or out, a few well-thought-out considerations will help you choose the right time and place to sow your seeds. You can ask yourself a handful of questions about the seeds you want to start, such as:
How long does it take to produce or blossom?
Does it do better with a head start inside?
What time of year do I want to sow it?
Does it transplant well?
Once you’ve considered those questions, it’s time to get organized.
Soil - Indoor Starting
A good commercial potting mix or seed starting mix is a great way to start seeds indoors, or you can make your own with a mix of peat moss and Perlite. Generally, you don’t want to use garden soil for seed starting as it may contain weed seeds or possible pathogens that might cause issues in the early stages of growth.
If you are starting seed indoors, pre-moistening your seed-starting medium helps it absorb water after sowing, making it easier to work with. Seed-starting medium is finer and fluffier than potting soil, holding an ideal amount of water and air for new seedling roots. After sowing seeds, cover containers with clear plastic or a clear dome until seedlings emerge. Take care to keep your soil moist, as germinating seeds are very sensitive to drying out, but avoid making the soil soggy by emptying any standing water from catch trays. While germinating, and when seedlings are small, water gently to avoid shifting seeds around; a mister works well for this.
When sowing outdoors, check the soil moisture frequently by dipping your finger in the soil, just past the seed depth. This is the area you want to keep consistently moist during germination, and then deeper after germination. Using a watering wand or watering can with a perforated water breaker will create a gentler stream so seed will be less likely to shift.
The recommended seed depth is listed on the back of the packet. Some seeds need to be covered by a generous amount of soil in order to germinate because they are large, and/or because darkness aids germination. Others shouldn’t be covered at all or just lightly pressed into the soil because they are very small, and/or light aids germination.
Have you ever experienced damping-off fungus? This common fungus can cause seeds to rot in the soil or it attacks seedling at the soil line, causing them to fall over and die. The disease can spread rapidly and wipe out an entire container in a short time. The first step in prevention is to use clean, sanitized pots and trays, with drainage. Do not use soil from your yard to start seeds indoors; it can contain pests and diseases. The best option is sterile, seed-starting medium from your local garden center. If you want reuse seed starting medium, sterilization is easy. Put medium in a shallow, oven-proof container (no deeper than 4″), cover tightly with foil, and bake in the oven at 180°F–200°F for 30 minutes. A sprinkle of cinnamon on the soil after sowing also helps stifle fungus like damping off.
Air circulation is also an important tool in preventing fungus. Place a small fan on low setting near your seed pots pointed near the containers but not blowing directly on the soil as it could dry out quickly. Finally, indoors or out, if you have sown a lot of seeds in a small amount of space, thin out the seedlings when recommended (see packet), as closely-packed seedlings provide the perfect environment for fungal growth.
Indoors, be sure to keep your grow lights on for at least 14 hours a day. This is important, as artificial light is not as strong as sunlight, and sufficient light is important for growing strong, sturdy seedlings.
A soil thermometer is a helpful tool for getting great germination. Seeds require a specific temperature range for germination to occur and that temperature varies among species. For example, peppers and tomatoes like to be between 70-80 degrees, and although easy to germinate in most indoor settings, will germinate better and more quickly with a heat mat underneath until they sprout. Conversely, sweet peas will germinate better in cooler soil that is only 55°–65°F. When taking outdoor soil temperatures, check the soil in the morning and evening to find an average as it tends to be less consistent than indoor soil. Check your seed packets’ sowing instructions for specific soil temperature requirements. Learn more from the article, Soil Temperature for Higher Germination.
Hard Seed Coat
Some seeds have hard seed coats and require “scarification” for germination to occur (e.g., sweet peas and morning glories). In nature, the hard seed coat helps to keep them viable longer. The fluctuating weather conditions of winter and early spring help to break down this coat naturally. There are a few easy ways to mimic Mother Nature and “scarify” them yourself. You can soak them in water for 12 to 24 hours, nick them with a file, or clip the seed coat with a nail clipper to allow water to get inside the seed. Any special requirements should be listed on the seed packet.
Stratification for Perennials
Some perennial seeds specifically require cold, moist winter conditions to germinate. You can “trick” them into believing that they have gone through winter by sowing them in pots with moist soil and placing them in the refrigerator for a few weeks. Or you can also sow them directly in the ground in the fall in the place you want them to grow, so they can go through natural winter conditions outside. Follow recommended planting depth and then tap them in firmly. Occasional watering in that area throughout the winter may be beneficial in dry climates. You may also try sowing them in containers outdoors. Even in cold climates, this can be quite effective. Use large pots filled with moistened potting soil. Sow your seeds as noted on the packet, then cover them with clear plastic and put them in a protected location. About once a month, or more frequently during warmer periods of winter, give them a sprinkle of water. Come spring, you will have a head start on your garden containers!
Different seeds have different needs. With a little extra effort, it is easy to ensure you are achieving fast and high-rate germination.