How to Germinate Seeds Indoors for Spring Success

It can feel like forever waiting for seeds to sprout once we've planted them. If you're feeling anxious - don't worry, it is still very early in the Kentucky growing season. Soil temperatures outdoors are not staying warm enough for long enough to properly germinate vegetable seeds outdoors. The question is, how can you germinate seeds now to get a jump start on the growing season?

Hiring a professional garden coach makes it easy as they always have helpful tips on seed germination in a jiffy! But for you DIY'ers... here are the dirty deets: 

#1. Seed Selection

You may start *most* lettuces, brassicas, and some herbs indoors now. EX: salad greens, cooking greens, broccoli, cauliflower, cabbage, kohlrabi, (wait on brussels sprouts), fennel, celery, green onions, dill, cilantro, calendula, nasturtium, etc.

It is not advised to start root vegetables indoors or very fast growing plants. EX: Carrots, beets, turnips, radish, parsnips, rutabaga, potato, snow peas, snap peas. Having to transfer a root crop from a container into the garden *can* disturb is roots and harm the plant. But hey, you are a gardener so you are a gambler anyway! You can always roll the dice and try anyway! Peas are very fast growers and will outgrow the indoors containers before its time to take them outside.

The above seeds are best directly sown outdoors once the soil temps are warmer - mid to late March in Kentucky. 

Plants like strawberries, asparagus, rhubarb, onions, leeks, & shallots are best grown from bare root "crowns" or in "sets" which are small dormant plants directly planted in Mid March.

Sweet potato "slips" are planted in late May - June in Kentucky.

Garlic is planted from cloves in October - November in Kentucky.

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 #2. Prepare a Quality Soil Medium

It's best to use a sterile, lightweight potting mix to grow your seedlings. Best avoid using or reusing soil from your yard. Start with a blend of peat moss, perlite, and lime for example. It’s best to moisten your soil before filling your germination containers. I like using black plastic trays that contain individual "cells" for each seed. The plastic allows the roots to develop evenly and retain moisture well as opposed to peat containers or egg cartons. They multi-cell trays are simple because you don't have to manage multiple containers. Next, pack soil firmly over tray to eliminate gaps. Put the seeds in place, label them, then cover firmly with more potting mix. Be sure the mix is moist and heavy. Seeds will not germinate in dust.

#3 Light Exposure

The three conditions for proper germination are: dark, moist, and warm. Most seeds germinate in the dark. Once they’ve sprouted the seedlings need about 16 hours of artificial light or 8 hours of direct sun to grow sturdy. If using fluorescent grow lights, it's a good idea to properly adjust the lights to about 4” above the seedlings as they grow. If using hotter lamps you will want the lights about 12” above seedlings as they grow. Rotate the containers if there is uneven growth among plants. If the plants are reaching too far for light, they will become leggy, weak, and won’t survive being transplanted outdoors.

#4. Water, Ventilation, and Nutrients

The main aim of seed starting indoors is to create optimal growing conditions AND to get ahead of the outdoor growing season. As your seeds sprout, one of the important steps on how to germinate seeds is by keeping the soil moist. You may use a mister or soft shower overhead setting when seedlings are tiny. Once they become more established, switch over to watering them from the bottom (like filling up the catch tray so the roots can pull the water up). Ensure proper ventilation by running a fan on a low setting to regulate air movement. Remember to regularly feed the seedlings with an organic liquid fertilizer like Monty’s or Fish Emulsion at the proper rate on the package. Keep the soil moist, the air moving, and the air temperature in the mid 60's. Some of us LIKE to use heat mats indoors, but they are A MUST if seed starting in a cold garage or hoop house.

#5. Gradual Outdoor Move

If you have been pampering your seedlings in the protected environment of your home, you will need to make a gradual move to the outer world. It's advisable to place your seedlings in a protected outer spot before you decide to set them in your garden. This process is know as “hardening-off” the plants. Expose them to the outdoors each day for a week, increasing in duration. For example, on day one leave them out for 1 hour, on day 2 - two hours, day 3 - three hours, and so on until the 6th or 7th day. By then they will have acclimated to the wind, sun, and temperatures for a higher likelihood of survival.

Conclusion

It may be difficult to wait for your seed to sprout, but the few tips mentioned above are very effective. At the end of the day, knowing how to germinate seeds effectively will get you early Spring wins!

Consult one of our Professional Gardeners for more hands-on help today! Our office hours are 10-4p M-F EST and 11-4p on Saturdays. The office line is 502-550-4109 or email us at [email protected].

PS- This video doesn't line up timing-wise BUT you learn the strategy!