How to Start Seeds Inside: Step-by-Step

Get ahead by sowing seeds under cover

February 25, 2020

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Growing starts with sowing. Give your seeds the best possible start and you’ll have lots of delicious harvests to look forward to! Get ahead by sowing seeds on windowsills or in greenhouses, tunnels and cold frames while it’s still too early to plant outdoors. In this short video, we’ll show you how to successfully sow seeds under cover, step by step.

Start seeds off under the protection of a greenhouse, tunnel or cold frame to get a head start on the growing season and raise strong, healthy seedlings safe from cold, drying winds and pests.

An indoor windowsill is often a convenient place to start seeds in pots or smaller seed flats. Use a propagator for tender crops like peppers and tomatoes or, for a cheaper option, secure clear plastic over the top of pots with a rubber band.

Cool-season crops such as onions, celery and cabbage can be sown on a windowsill then moved into a greenhouse, tunnel or cold frame once they’ve germinated. Alternatively, continue to grow seedlings on indoors under grow lights.

The Right Time to Sow

Sowing too early means you’ll need to transplant seedlings into bigger containers more often while conditions aren’t yet good enough for transplanting outside. This wastes potting mix and takes up valuable space under cover. Use the Plant List in our Garden Planner to work out the perfect time to sow and plant in your garden’s location.

Seed Flats or Plug Trays?

Use seed flats for sowing very tiny seeds such as basil, or easy-to-transplant flower seeds. Seed flats are space-efficient during the first stage of growth. When your seedlings are big enough to handle, they can be transplanted into their own pots or plug trays.

Use plug trays with larger plugs for sowing bigger seeds such as beans, and smaller plugs for crops like lettuce and onions.

Trays may be made of plastic or biodegradable fiber. Alternatively, make your own newspaper pots.

Sowing in Plug Trays

Screen all-purpose potting mix to a fine texture. Fill the trays with the potting mix, then make shallow depressions with your fingertips. Most seeds don’t need to be sown particularly deep—about a quarter of an inch is fine for most crops. Drop seeds into the holes you’ve made, then sieve a little more potting mix over the top, making sure all the seeds are buried. Water trays carefully using a watering can or hose pipe fitted with a fine rose. Label trays with the variety and date of sowing.

Lift trays and pots regularly to check the weight and gauge how much moisture is in the potting mix. If it’s light, water.

See the Almanac’s full guide to starting seeds indoors.

Try Out the Almanac Garden Planner for Free. 

As a courtesy, the online Almanac Garden Planner is free for 7 days. This is plenty of time to play around on your computer and try it out. There are absolutely no strings attached. We are most interested in encouraging folks to try growing a garden of goodness! 

Try out the Garden Planner on your computer (for free).


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