seedlings starting to emerge from seed traysApril showers bring May flowers. That’s what they say, and sure enough, spring rains are important for our gardens. If you didn’t get to start seeds in March, then April is the time to begin, and no, you’re not behind!

My motto with seed starting is “Always better late than early.”

How many times have we had warming weather at some point in April or May, only to be hit with a sudden cold spell and a frost around Memorial Day, or even later? Seeds started later will benefit from the good conditions and thrive.

In Downeast Maine the average last spring frost date is around June 1st. This is the date when it is safe to plant most flowers, veggies and herbs outside. Of course there are some that like the cold and can be planted outside earlier and there are some that prefer to be planted out in mid to late June when the soil is warmer.

Here’s a guide for when to start your seeds indoors in order to be ready to plant them outside in May or June:

1st week of April (start indoors)

  • onions (if you didn’t start them in March)
  • leeks
  • scallion
  • sweet & hot peppers
  • eggplant

Mid-April (start indoors)

  • broccoli
  • cabbage
  • kale
  • kohlrabi
  • caulifower
  • lettuce
  • herbs like oregano, thyme, sage, basil

Late April (start indoors)

  • lettuce (again)
  • tomatoes
  • flowers! like zinnias, cosmos, marigolds, bachelor buttons, lavatera

Check out instructions from our March blog on how to start your seeds, but here are a few tips for the some of the veggie types listed above. And remember, the seed packet itself gives you lots of good information about when and how to plant.

Kids around a sled of soil

Getting ready to plant seeds. Photo from 2019 Container Gardening Workshop.

Broccoli, cabbage, kale, kohlrabi and cauliflower (brassica family)

  • Prefer cooler weather, and can even tolerate a light frost, so they can be transplanted out to the garden in early to mid May.
  • You will be impressed by how happy they look on a cold day!
  • Since they can take the cool weather, be sure to set the seedlings outside each day to prevent them from getting “leggy.” Tall skinny plants are not as resilient as shorter, stout plants.

Peppers, tomatoes and eggplant

  • Especially like warm soil in order to germinate. You can use a heat mat if you have one (they’re a little pricey) or you can just use a regular heating pad, removing the cloth covering.
  • Simple set your seed flats or pots, containing soil and planted seeds, on the heating mat.
  • Be sure to check a couple times a day to be sure the soil stays moist– not drenched like mud, but nicely saturated. I often pick up the flat to notice the weight– it helps me figure out if the soil is saturated or just the surface is watered. If the flat feels super light, it needs more water!
  • When it’s time to transplant them to their own pots, I like to use pots that hold about 2- 4 cups of soil, because they will stay in these pots for a while. I want to give their roots plenty of growing space! These vegetables love warm soil, so they will not be transplanted to the garden until mid June.


  • like to be transplanted outside to the garden as early as the soil is workable, meaning it’s not too wet or muddy, from spring rains.
  • You can determine this by turning over some soil in your garden bed. Take a fistful, squeeze it, and open your hand. If it is so wet that it holds together in a firm ball, it’s still too wet to plant.
  • Onions tops like lots of growing time in the garden before the summer solstice on June 20. Once the days begin to shorten after the solstice, all the plants energy can go into growing large bulbs in the soil.


  • Start flower seeds the same way you start vegetable seeds (March blog)
  • Depending on the variety, seeds can be started indoors 4 – 8 weeks before setting out in the garden, or in a container in your yard.
  • Most will be killed by a frost,  so don’t transplant outside till early June.

Find yourself a gardening buddy — it’s extra fun to learn about gardening with family and friends. The main thing is have a good time and share what you learn along the way!




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