How To Germinate Seeds Indoors

March 4, 2011 at 3:06 pm Leave a comment


Starting seeds can chase away the winter blues. These coleus will look fabulous in the garden and containers in about 6 weeks or so.

Some folks kick off the gardening season when they venture outside on the first warm days of spring to begin cleaning up their yards–fluffing mulch; removing fallen sticks and leaves; cutting back the dead foliage on last year’s perennials to make way for new growth. I love getting outdoors in the spring as much as any gardener, eagerly poking around in the mulch looking for a sign of the first crocus or hellebore’s appearance, but I’m also impatient. That’s why, in mid-January when the snow is flying and the air is still frigid, I begin shopping for seed starting supplies, knowing that within a week or two I can have green things growing right here in my home office.

If you’ve shied away from trying to germinate seeds indoors, or if you’ve let previous failures keep you from trying again, buck up, little camper! Seed starting is easy once you learn a few simple tricks.

Let There Be Light

Not all seeds need light to germinate, but every seedling needs light to grow. Remember that and you’re already well on your way to success. No matter how sunny your south-facing window may happen to be, it does not provide enough light for tender young seedlings to thrive. You need artificial light.

This light setup cost me less than $160 to make. Similar professional setups cost $500-600 in catalogs.

I’ve already explained how to build a simple, budget light stand for seed germination. Check out that article if you want to get started on a bit larger scale. But if you just want to try starting a few annuals or maybe some tomato or pepper plants, all you need is a single shop light and a place to hang it. You’ll need to keep your light source just inches away from your seedlings, so keep that in mind as you’re planning.

When purchasing bulbs for your shop light or light setup, don’t worry about getting expensive grow lights–all you need are some regular fluorescent bulbs. Bulbs come in different color temperatures–warm and cool. Warm lights provide either an amber or pinkish-purple glow while cool lights cast a blueish tone. Cool toned lights (I prefer the ones marked as “daylight”) seem to work best for germination. If you want your plants to flower or put on buds before you set them outside, mix a warm light in with your cool bulb (most shop lights have at least two bulb fixtures, so use one cool bulb and one warm) to broaden the light spectrum.

If you want to succeed with germinating seeds don’t skimp on the lights. Ambient light from your house lights or a window really won’t do, so make the investment. And, honestly, it’s not a big investment. One shop light and the accompanying bulbs will cost you $20 or less. It’s well worth it to get your seedlings off to a good start.

Seed Starting Containers

The Burpee Ultimate Growing System is one way to get seedlings off to a good start. It's not particularly cheap, but it is reusable.

You can start your seeds in just about anything–plastic flats, small plastic fast-food containers…anything that either has holes in it or that you can make holes in to provide adequate drainage. Although you don’t need to spend money on seed starting kits, I’d be remiss if I didn’t admit that I’m a big fan of the Burpee Ultimate Growing System. While some people aren’t crazy about the pelleted growing medium that comes with the system (I happen to like it), most will concede that their setup works very nicely for keeping seedlings growing in moist, but not overly wet, conditions. The Burpee system works by providing a watering tray and a stand that rests on small pegs. You drape the stand with a moisture-retaining mat, which wicks water up from the tray to the seedlings, watering them from the bottom up. The Ultimate Growing System isn’t particularly cheap ($20-25 for a 72-cell system is average), but it’s effective and reusable.

No matter what you choose to start your seeds in, make certain that it has drainage holes and a watering tray. The tray is important, because you’ll want to water tender seedlings from the bottom up by filling the tray with water, letting the soil soak it up through the drainage holes in your container, and then dumping the excess water out of the tray to prevent water-logged seedlings. (This is yet another reason why I like the Burpee system–watering is convenient and goof-proof.)

Growing Material for Seed Germinating

Whatever you do, don’t use garden soil for seed starting. Not only is it too heavy, but it’s teaming with bacteria and insects and other things that nature manages to keep in check outdoors, but that become destructive to seedlings in an indoor environment.

The best seed starting medium is a soil-free mix, usually containing peat moss and something to retain moisture and aid drainage, such as perlite or horticultural vermiculite. Seed starting mixes should be sterile, and most mixes labeled specifically for seed germination will be. Regular potting soil can work but is generally a little too heavy for seed starting. So take a little extra time to look for a good mix specifically for germinating seeds.

Sowing the Seeds

Once you’ve got a good light source, some seed starting containers, sterile seed starting mix and seeds…you’re ready to roll. Here’s how to sow your seeds step-by-step:

Step 1

Pre-moisten your seed starting mix (unless you’re using a pelleted form; then simply follow the manufacturer’s directions.) I use a large stainless steel bowl, a big serving fork, and some hot (or even boiling) water in a small watering can. (The hot water helps to keep the mix sterile, but also makes your starting mix warm and inviting for the seeds you’re about to plant.) Simply dump some starting mix into the bowl, add some water and stir it up.

You want the consistency to be fluffy, crumbly and moist, not soggy and wet. If your mix is too wet, add a little dry mix until you’ve got the right consistency. The mix should be moist enough to stick to your fingers but not so wet that you can’t easily brush it off your hands.

Step 2

Fill your seed starting container (flat, cells, what have you) with the starting mix. Tamp it down lightly and add more mix if necessary. You want the mix fluffy and light, not compacted.

Step 3

Plant! Simply follow the directions on your seed packet. The seed packet will tell you everything you need to know about germinating the seeds. Keep in mind that some seeds need special treatment prior to being planted such as soaking, “scarification” (nicking the seed shell) or “stratification” (a cooling period.) When you’re just starting out, you might want to begin with seeds that don’t require much in the way of special handling. Tomatoes and peppers are easy if you’re interested in growing veggies. You also can’t go wrong with most annuals–coleus, petunias, pansies, zinnias and others are all very easy to start indoors. Read the seed packet before you purchase it to make sure you have time to get the seeds started. Those that require stratification can take some time to germinate due to the special handling required, and some seeds take longer to germinate in general.

Be aware that some seeds require light to germinate. (If light aids germination, just press those seeds into the soil a bit to ensure good contact with the soil surface.) Others don’t need light, and you can cover them as directed on the seed packet. Some people press their seeds into the soil to the recommended depth using a pencil tip or some other implement. I usually just sprinkle dry seed starting mix over the top of them (the mix will moisten when it comes in contact with the damp mix you’ve planted in.) Either method works.

A word about warmth: Most seeds like a warm environment for germination. (Check the seed packet.) Some gardeners use supplemental heat mats to keep the soil warm. Personally, I prefer to keep my seed starting setup in a warm area of my home and avoid the hassle of heat mats. As long as the temperature stays about 60 degrees or so at night, and warmer during the day, your seeds will probably sprout without any help.

Step 4

Keep your seeds moist, but not wet. It’s best to keep them covered (either with a single layer of plastic wrap, a clear plastic bag, or the plastic domes sold with seed starting flats.) Keep the mix moistened either by watering from below when it becomes dry (water into a try and let the soil soak up the water through its drainage holes) or, the method I prefer, mist them gently with a spray bottle.

Mark which seeds you’ve planted where. I use cheap plastic garden markers but you can also use things like Popsicle sticks or the handles of plastic utensils. On your marker, write the plant name, the date you planted the seeds, and the expected time to germination. Once again, your seed packets provide a wealth of information–they’ll tell you how long you can expect it to take your seeds to germinate.

If your seeds don’t germinate in the expected time, don’t give up too soon. Give them another week or so and occasionally your patience will be rewarded.

I started these culinary herbs indoors from seeds in the dead of winter and now I have fresh basil, cilantro and chives whenever I need them.

Step 5

Once your seedlings have sprouted (hooray!) you can remove any heat mats, plastic or domes you’ve used, since the seedlings will require good air circulation. Keep them watered regularly–don’t allow the soil out completely. Again, water from below, or mist, or use a wicking mat like the Burpee system uses. Top watering only washes out tender seedlings so try to avoid it.

Every week or so, add a commercial fertilizer to your watering regimen. I like organic fertilizer like fish emulsion, but any balanced fertilizer (10-10-10 or thereabouts) will do. Use the fertilizer at one quarter the recommended strength when the seedlings are tiny. You can increase to half strength as they grow and move up to full strength just before you’re ready to put them outside to harden them off.

Step 6

Ready to plant your seedlings out? Not so fast! You need to harden them off. Hardening off is a term that refers to getting the seedlings accustomed to outdoor conditions gradually before putting them into the ground or a container. To harden off, place your seedlings outdoors in a sheltered location out of wind and direct sunlight. (If it gets particularly cold, you might want to bring them into an unheated garage or shed at night.) Gradually expose them to the elements–sun, wind, rain, cool temperatures–each day over a period of about a week.  Once they’ve become acclimated to life outdoors you’re ready to plant.

There’s nothing like planting out the young plants that you started and nurtured from tiny seeds. Not only will you save money by starting your own vegetables and annuals from seed, but you’ll have the benefit of knowing just how those seedlings were raised (without chemicals, if organic is your thing.) You’ll also be able to experience the pride of doing it yourself. There’s nothing like it!

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Entry filed under: Gardening Tips. Tags: , , , , , .

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