Seed Starting: When to Start What?

About this time of year, the itch to start seed starting hits. Those late winter snowstorms send gardeners into their basements to find their lights and flats and double check their stash of seeds to make sure they have all they want. Some gardeners can't wait even this long, and for them there is winter sowing.

Tomato seedlings thrive under lights.

If you prefer to start seeds indoors, most annuals and vegetables should be started between early March and mid-April in Minnesota. The University of Minnesota Extension service has a fine post about seed starting and recommends that brassicas (cauliflower, broccoli and cabbage) as well as lettuces be started indoors in early to mid-March. (Onions and celery need an even earlier start.) The brassicas are cold-weather crops and generally can be put outdoors earlier and do well in cold frames or hoop houses. A long list of popular annuals, such as petunias, ageratum, coleus and snapdragons, can also be started from seed in early March.

In mid- to late March, plant your peppers and eggplants as well as marigolds, annual phlox, cleome and hollyhocks. These all need eight to 10 weeks indoors under lights before the last frost date.

Hold off until April before doing your seed starting for tomatoes. While some folks plant them earlier, the U recommends waiting. My experience is the seedlings are stronger if they are started later, though I'm sure with enough light and fertilizer you can grow very large plants indoors by giving them more time.

April is also a good time to do seed starting on annuals such as baby's breath, morning glory, nasturtium, cosmos and zinnias. Some of these annuals can also be sown outdoors after the last frost date for a later bloom.

To learn more about seed starting, check out our articles here, here and here.

Ready to grow? Save a spot in an upcoming webinar or workshop!


  1. Laurie Ashworth on February 24, 2019 at 4:26 pm

    I am going to start a small garden in my back yard this Spring. I will limit what I plant to cherry tomatoes, spicy lettuce, peppers and a few green beans. I don’t know where to buy small quantities of seeds that are fresh. Could you recommend some websites or stores? I live in White Bear Lake.


    • Mary Lahr Schier on February 25, 2019 at 1:53 pm

      Laurie — Most garden centers should have the seeds (or plants) you need. There is a Bachmans on White Bear Avenue, but any garden center would have lettuce, tomato plants or seeds, etc.. If you prefer to start everything from seed, Seed Savers Exchange is a good mail order company, but I’ve also bought seeds from Burpee, Jung Seeds, Renee’s Seeds and Botanical Interest and had good luck with all of them. Enjoy your new garden!

    • Terry Roy on March 10, 2020 at 9:51 pm

      Laurie, I am in WBL and if you just want a few seeds instead of an entire packet I’d be happy to share. Alternatively, a site called Seeds Now offers small sampler packs of non gmo veg and flower seeds for 1.99 each. The White Bear Library also has a Seed Bank! You can email me terzap (at) gmail com with what you’re looking for, I grow at least 20 different kinds of veg (6 types of beans alone, lol)! I don’t start toms or peppers from seed though.

    • Mary Lahr Schier on March 11, 2020 at 2:00 pm

      Laurie — See Terry’s comment above for ideas. The seed collection at the White Bear Lake Library is a great options. (We’re doing an article on it in Northern Gardener this fall, too.) Most gardeners have extra seeds around to share.

  2. Marilyn Thomas on March 1, 2020 at 11:56 pm

    I am new to the area; a transplant from the south. I’m helping my daughter with her garden this year (I’ve had many southern gardens) and look forward to any help I can get on growing in this area. Thank you for being here!

    • Mary Lahr Schier on March 2, 2020 at 12:53 am

      Welcome to Minnesota! You may want to check out some of our classes as you get oriented to the area.

  3. Katherine on March 26, 2020 at 5:01 pm

    Should I spout my seeds in a damp coffee filter inside a bag or just put them in soil under a grow light?

    • Mary Lahr Schier on March 31, 2020 at 6:13 pm

      Just put them in seed starting mix or potting soil and under the grow light. The only reason to sprout in a coffee filter is if the seeds are somewhat old (ie from a year or two ago) and you aren’t sure if they are still viable. If they germinate in the damp coffee filter, they are viable.

  4. Jonathan Preus on March 30, 2020 at 10:43 pm

    I have left over seeds from last year and before. Tomatoes, radishes, beans, lettuce, cauliflower and others. Which of these old seeds are most likely to sprout, which least likely? I will try a few, but would appreciate your advice as to which plants’ seeds stay viable longer. I learned something last year – a small plot where flowers had grown for years proved to be very good for tomatoes, when I moved the flowers and put in tomato seedlings.

    I just found your info online by accident, after years living in Lauderdale! Would like to visit your office – open hours?

  5. Dee Haataja on April 13, 2020 at 7:25 pm

    I am from northern Minnesota, North of Park Rapids. Isn’t a different zone? Thanks Debbie

    • Mary Lahr Schier on April 13, 2020 at 7:54 pm

      Yes, you’re in USDA Hardiness Zone 3. So, it would probably be a good idea to move all the seed starting dates up a couple of weeks. You could plant tomato seeds (indoors under lights) about now to plant out in early June.

  6. Jayne on April 18, 2020 at 7:29 pm

    Hello! Twin cities gardener here with a little greenhouse on my deck. Past years I burned my poor plants in it, but I am home to keep an eye on them this spring. :). Anyone recommend starting tomato seeds in the greenhouse mid-April? Will it get too cold at night? You think there’s enough sun light? I am adding better vents in the greenhouse to treive heat if needed, but also worried about that seed starting mix drying out.

    Thanks for any advice. I have started marigolds and sunflowers from seed on my kitchen counter under the counter light. They have been repotted and are now cozy in the greenhouse.

    • Mary Lahr Schier on April 19, 2020 at 3:31 pm

      As long as you can monitor the temperature well, you should be fine.

  7. Amy B. Mingo on May 7, 2020 at 3:07 am

    I have 2 4×4 raised beds I am prepping with garden soil and compost. I was unable to get seeds until last week so am late to start them. Can I plant directly? I have so many heirloom seeds that came in my order and don’t know if I can plant them all or should save some for starting next year. I have arugula, asparagus, bush beans, beets, broccoli, Brussels sprouts, cabbage, cantaloupe, carrots, cauliflower, celery, corn, pickling cuke, eggplant, honeydew, kale, 4 kinds of lettuce, yellow onion, peas, cayenne, jalapeno, banana and bell peppers, pumpkin, radish, spinach, squash, swiss chard, cherry and beefsteak tomato, turnips, and watermelon. Whew. Any help you can give me would be great. Im 52 but this is my first veggie garden ever. I am able to use cages and trellises for things to climb and be stabilized as well. Thank you so much.

    • Mary Lahr Schier on May 7, 2020 at 1:07 pm

      Wow, that is a lot — especially for a first vegetable garden. I’m not sure how much space you have, but it might be a good idea to focus on the vegetables you like the most this year. Many of the seeds you have can be planted directly, such as arugula, Swiss chard, lettuce—any of the greens—plus melons, beets, cucumbers, radish and squash. Tomatoes, eggplant and peppers are usually started indoors in mid-April, so you are a bit late for those, but you could try. If you are growing onions from seeds, I’d hold those until next year as they take a long time. Asoaragus is a more complicated crop to get started. You may want to research that a bit before planting. Good luck!

  8. Mugdha Halbe on November 17, 2020 at 7:01 pm

    Last year some of seeds from my annual flower fell on the ground and they germinated it self, when I saw plants growing, I dug them and put them in the pot and they did well. So it forced me thinking may be I can do the same thing with my other annuals, just put them in the ground now(for 2-3 annuals I already did it), and then they will geminate as nature allows.
    Would be ok, if I do that now this week since ground is not really frozen, for some more spring and summer flowers?

  9. Joe Vail on February 23, 2021 at 2:00 am

    Question on plant availability and seed starting.

    We love pickles and have done a bit of research to find small cucumbers that make excellent pickles (Boston, straight 8 etc) Do places like Bachmans and the like sell these plants in the spring or do I need to start from seed? Also, last year we were not able to find sugar snap pea plants so do I need to start those from seed as well? Lastly, do I need a growing light to start all plants from from seed? #neverdonethisbefore I cleared brush and built a raised bed last summer. A u-shape with door and 6ft fencing and put in irigation drip lines so once I plant they really take off.

    open for any and all suggestions

    • Mary Lahr Schier on February 24, 2021 at 4:14 pm

      Joe — you will find a variety of vegetable plants at Bachman’s and other nurseries in spring. You could also check local farmers’ markets, which sell plants early in the season. For indoor seed starting, lights are a good idea, though cucumbers can be started outside in the ground in later spring and still do well. Here’s a blog post with details on seed starting:

      Sounds like you have a great set up for your garden!

  10. Dan on March 28, 2021 at 5:15 pm

    Live in Hibbing, looking for indoor start time for tomatoe seed planting, seeds are an un named variety that came from Amish farmers in Ohio.Dan

    • Mary Lahr Schier on March 29, 2021 at 4:44 pm

      Anytime between now and mid April would be OK for seed starting. Check your last frost date — you may not want to transplant seeds outside until early June.

  11. Vpk on April 3, 2021 at 12:22 am

    Hi, I am in southern minnesota, I am wondering what kind of soil should be used if I am using inground veggie gardening? Please suggest. Thanks!

    • Mary Lahr Schier on April 5, 2021 at 5:53 pm

      Your local garden center or home store will have a garden soil mix that will work well in a raised bed over the ground. If you are creating a garden in the soil you have, you might want to add some compost for vegetables.

  12. Paula on May 1, 2021 at 4:40 pm

    Hi. It’s may 1st today, by Zimmerman. Can I start my seeds now in a green house (no under lights, but outside)? Or are there seeds I should not start right now due to being a little late? What will happen if I plant them now? Pumpkins, watermelon, cantaloupe, carrots, beets, corn, beans, peas, cucumbers, tomatoes??
    Also when should I plant my potatoes??

    • Paula on May 1, 2021 at 5:10 pm

      Hi, when should I plant my dahlia bulbs?

    • Mary Lahr Schier on May 4, 2021 at 4:45 pm

      You can plant your potatoes now. I don’t have a greenhouse, so am not sure what the best recommendations are. It is a bit late to start tomatoes indoors under lights. You could try in the greenhouse, though. Carrots and peas can be planted outdoors now. The rest of your list could be started in the greenhouse or wait a couple of weeks and plant outdoors. Hope this is helpful!

  13. Tey on May 6, 2021 at 2:57 pm

    Hi, I am in Duluth mn right by the lake. I started tomatoes from seed indoors and they have gotten quite large. Wondering when I can plant them outside (I plant them in large pots)?

    • Mary Lahr Schier on May 7, 2021 at 4:23 pm

      Tey — I’m having the same issue. My indoor plants grew faster than expected. The usual recommendation is nights in the 50s before you can plant them outdoors without protection. If nights get in the 40s and you can provide some protection (covering at night, for instance) they might do OK. I’m trying to hold mine (in the Twin Cities) another week or 10 days indoors at night and outdoors in the day.

      • Tey on May 8, 2021 at 12:20 pm

        Thank you Mary,this helps. I am so anxious to get them out there but will do my best to hold out until next weekend! We are supposed to see 60s for day time Temps starting Tuesday

  14. Mark on June 15, 2021 at 7:05 am

    Timing is also important in plant seedling. Planting indoors is good.

Leave a Comment