Growing Together: The easiest flowers and vegetables to start indoors from seed

Seed starting mix, heat mats and covered trays help seeds get off to a rapid, healthy start. David Samson / The Forum

It’s well-known that gardeners are a frugal bunch. Why else were thousands of zucchini recipes invented just to prevent overgrown zucchinis the size of small orca whales from going to waste?

And I doubt I’m the only one who yells “Eureka!” at the garden center every time I find a fifth tomato seedling in a pack selling as four. Thrift is one reason many of us start seeds indoors to grow our own vegetable and flower transplants. It’s a fun hobby and makes spring seem closer.

But if we enjoy starting seeds, it doesn’t mean we’re obligated to produce all our own transplants. Some types are difficult to grow under home conditions and are maybe better left to the ideal environment of the local greenhouse. We can focus our efforts on starting seeds of flowers and vegetables that are most successfully homegrown.

The easiest types sprout quickly, emerge strongly and don’t require as much indoor growing time. Such seeds are comparatively large. The easiest flowers include zinnia, marigold, cosmos, calendula, four o’clock, nasturtium, cleome, alyssum and salvia, while the easiest vegetables include tomato, pepper, cauliflower, cabbage, broccoli, cucumber, squash, pumpkin and melons.

The more difficult flower types require extended months of growth and must be seeded in midwinter. Seeds of these types are quite tiny, the size of poppy seeds sprinkled on some bread types or even smaller. The slightly-more-difficult-to-grow category includes petunia, begonia, dusty miller, snapdragon, poppy, pansy, lisianthus, impatiens and coleus. They’re not impossible — they just take longer and require greater attention.


Flower and vegetable seeds that are easiest to start indoors germinate quickly, grow strong and require fewer weeks to develop. David Samson / The Forum

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Dates to start easiest-to-grow flowers indoors: Based on growing conditions in zones 3-4 for transplanting outdoors into flowerbeds May 15 to 25.

  • March 15 (require 8 weeks): Alyssum and salvia.
  • April 1 (6 weeks): Marigold and cleome.
  • April 15 (4-5 weeks): Zinnia, cosmos, calendula, four o’clock and nasturtium.

Dates to start easiest-to-grow vegetable transplants:

  • March 15 (8 weeks): Pepper, cabbage, cauliflower, broccoli and Brussels sprouts.
  • April 1 (6 weeks): Tomato.
  • May 1 (2-3 weeks): Cucumber, squash, pumpkin, watermelon and muskmelon.

Additional tips

  • Avoid starting too early. Seeding earlier than recommended usually results in plants that become weak and spindly from being held indoors too long.
  • Instead of using potting soil to start seeds, choose a mix specially formulated for the purpose, like Jiffy Mix, Miracle Gro Seed Starting Mix and Burpee Seeding Mix. Moisten these dry mixes the day before using by adding water to the bag and stirring to distribute.
  • Without proper warmth, seeds languish and can take twice as long to germinate, if at all. Germination heat mats are inexpensive and well worth the investment.
  • Instead of seeding directly into the final cell packs, sow in seed trays and transplant when seedlings develop their first true leaves, as the transplanting process results in stronger plantlets.
  • Seedlings quickly stretch and become spindly if adequate light isn’t given upon germination. Locate seed trays 1 to 2 inches below fluorescent or grow lights or move to a very sunny window.
  • Melons, cucumbers, squash and pumpkins are best started in peat pots so the entire unit can be transplanted into the garden, as these types resent having their roots disturbed.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Readers can reach him at

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