It is that time of year again to question if your just tired of winter and wanting to grow new green things or or if it really is time for seeds to be starting. So, here are a few things to remember about when looking around the garden center and wondering just when seeds should be started indoors.
- NOT ALL SEEDS: First thing is that not all seeds need to be started inside or will even thrive if they are started indoors. Many veggies prefer to only grow outdoors and tend to be dramatic about transplanting.
- Plants that do not transplant well and are therefore best started outdoors or in containers include cucumbers, muskmelon, pumpkins, squash, and watermelon. These are all tender, however, so refrain from sowing them outdoors while frost is still a threat.
- Root vegetables, like carrots, turnips, and beets, don’t like having their roots disturbed, so it’s usually safer to just start their seeds outdoors in the ground rather than transplant them later on. Plants with long tap roots also do not like to be transplanted; examples include dill and parsley.
- Finally, plants like radishes and peas are so fast growing and cold tolerant that it just makes sense to get them right in the ground!
- Best for Indoors: broccoli, brussels sprouts, cabbage, and tomatoes. Those with a slower root development, like cauliflower, celery, eggplant, and peppers, should also be started indoors.
- Tender vegetables like tomatoes, eggplants, and peppers are very susceptible to the cold temperatures of spring, so it’s best to start them indoors and keep them safe from unpredictable weather.
- Starting Indoors Timeline: As a general rule, most annual vegetables should be sown indoors about six weeks before the last frost in your area. Look for your frost dates here. Your seed packet will often list when the seeds should be started indoors. For example, it may say, “start indoors 8 weeks before last expected frost date in your area.”
The right container: You can sow into pots/single seed trays or into plug trays/module trays. Each has its advantages:
- Sowing into pots or a single tray container is more space efficient, as the young seedlings take up less space initially. It’s a more efficient use of seeds, too, because you can germinate the seeds in a pot and then transfer every single seedling into its own pot or plug. Sowing into a single container can also be useful for sowing very tiny seeds such as basil or easy-to-transplant flower seeds. For easy, cool-season crops—everything from onions to celery to cabbage—you can sow multiple seeds in the same container seed flat. You can even stack trays up after sowing to save on space. After two or three days, start checking daily for signs of germination then move them out to the greenhouse or cold frame to continue growing. Or you can continue to grow seedlings on indoors, using grow lights to ensure strong, even growth.
- Plug trays, on the other hand, are containers with individual pockets for each seed. They remove the need to transfer seedlings as often, minimizing root disturbance. Simply sow them into the plugs then grow them on until it’s time to plant them, though they may need transplanting into bigger plugs or pots if the roots fill their plugs before it’s time to plant them out. Two or more seeds are usually sown per plug and then the germinated seedlings are either left to grow on as a cluster or thinned out to leave the strongest seedling in each plug. Trays with smaller plugs suit most leafy greens and radishes, especially if they will be transplanted promptly (within three or four weeks of sowing). We also like this method for cluster-grown crops such as beets or beetroot and salad onions.
We often repurpose food containers such as yogurt cups and sour cream containers as seed starting containers. Simply clean them out and poke a few drainage holes in their bottoms. They are generally large enough to house one or two small seedlings for a few weeks. Eventually, seedlings will need to be transplanted into their own pots.