Five Keys to Successful Seed Starting
As spring slowly approaches, many gardeners start thinking about growing plants indoors from seed. Here are the five things you’ll need to consider.
Your seeds won’t germinate (sprout) if they are not kept evenly moist. Thoroughly moisten the seed-starting medium (not garden soil!) before sowing the seeds.
Keep a plastic lid or loose plastic bag over your seed pots or trays to keep the moisture in like a mini greenhouse and you probably won’t have to water again until the seeds germinate. However, check periodically to make sure the growing medium is damp (not soaking wet or it will get moldy and the seeds will rot).
Avoid letting them dry out – soil pulling away from the sides of the pot is a sign that it’s drying out. If the medium seems dry, give it a spritz of H20 with a mister. Misting is much gentler than a watering can and won’t dislodge your delicate seeds.
Different seeds like different temperatures to germinate and thrive. There are a few crops that prefer cool soil, like spinach and peas, so you can sow them directly outside when the soil can be worked. But most other seeds, including tomatoes, peppers, and cauliflower, need some heat to sprout and grow nice stocky plants (typically, mid- to upper-70’s is ideal).
You can buy heat mats from gardening stores or catalogs or you can DIY by supplying bottom heat by putting your seed flat on top of the refrigerator, television, or other warm spot. A 40 watt incandescent bulb positioned just under a metal shelf pointing up makes a good heat source for seed pots placed on the shelf – just ensure the shelf is metal and there is no threat of fire!
Once your seeds germinate, they need lots of light or you’ll end up with weak, spindly plants. Your light can come from a very bright window that keeps your seedlings in bright, direct sunlight all day (not very common) or from artificial lights. Although the fancy ‘grow lights’ tend to work best (after all, that’s what they were designed for), any fluorescent light will work.
What’s critical is that your light source is just 3 or 4 inches above your plants. As the fluorescence gets farther away from the plant, the physical benefits of the light decrease, so do what you need to do to hang those lights close to the plants. Most of us aren’t concerned with attempting a decorator look with this – a contraption fashioned from plant hooks in the ceiling, string, and wire coat hangers works wonders.
Start off with 24 hours of light a day and gradually decrease it to about 14 hours as the seedlings develop true leaves. Get your light timer from your holiday closet and set it to turn on early in the morning and turn off at dinner time.
Many of us have transplanted our delicate seedlings outside into the garden and come back the next morning to find our itty bitty plants flattened and broken by the evening’s pelting rain or gusty wind. An age old trick for growing sturdy, stocky plants that can take the outdoor weather is to have a very light breeze floating across the plants throughout the day. If the tiny seedlings feel that breeze they will grow thicker stems which will help protect them when you transplant them outside. Use a small fan positioned far enough from the seed trays to create just a light breeze.
Once your seedlings develop true leaves, they’ll need supplemental feeding to continue producing strong, healthy growth. There are plenty of fertilizers developed specifically for seedlings but, generally speaking, any liquid house plant fertilizer at half strength will do.