I have seeds that I have collected from my own flowers and also store bought seeds left over. I would like to know the best time to direct sow them so that they will sprout and grow in the spring. Can I sow them now or should I wait until just before the snow flies or wait until after our last frost in the spring? I am in Iowa, Zone 5a. I will be sowing them in my raised beds that are 3 landscape timbers high and are 4' X 8'. Thank you for your help.

I am perhaps the last person to comment on this question, but for me at least, I would sow those seeds in the fall, certainly before the snows come. Here in the south, depending on whether the flowers are somewhat hardy or not, I might sow some varieties of seeds now and have them germinate and then grow and bloom in the fall. If you want spring germination, this is not the time to sow them.

Some of it depends on what kinds of flowers we're talking about. Annuals may not bloom in time while perennials may have time to get large enough to withstand winter temps and snow.

What do you have?

I am in Iowa along the Mississippi River. I am in Zone 5a. I am talking about mostly perennial seeds and some annuals such as Zinnia and Cosmos. I had Cosmos self seed and also Petunias. They drop their seeds in the fall and then grew in the spring. The germination rate may not have been the best. I can grow a few seeds in my garage under gro lights in the winter which I did last winter for the first time. Our garage is heated. I just would like to grow flowers for cutting in my raised beds and wanted to get a jump on them growing and blooming when they should. Any suggestions are appreciated.

Ken and Celia for your comments.

The answer for commercial seed mixes is kind of "good luck" since each variety has its own preferences. Do the store-bought mixes have any advice on the seed packets? That's a starting point for each mix. (I think that when I have planted mixes, some of the seeds stay dormant for a year or two, then give me surprise "volunteers" for 2-3 years.)

With saved seed, each species has its own preferred time of sowing. Big seeds with hard coats probably need scratching and soaking, whereas dust-like seeds are their own pain-in-the-butt. It does seem too late this year to sow annuals in Iowa Zone 5. What's your average first frost date, late September? Save annuals for next Spring.

Maybe "spring-winter-sow" SOME annuals as a low-effort way to establish some seedlings without insect pressure or fussing to keep soil evenly moist for weeks. Start them in plastic, covered flats in some shade, before the last frost. They'll germinate when the sheltered tub reaches a suitable temperature, earlier than the soil in a raised bed would have started them. The covered tubs will protect them from wind, rain, insects and slugs. When they sprout, pop the lid and start to harden them off. When they're big, plant them out in chunks.

Or, if you have LOTS of saved seed and didn't give most of it away, you can simply broadcast annual seeds thickly in spring and rely on vast numbers of seeds to overcome less-than-ideal germination conditions.

When in doubt about the best way to sow mixed perennials, split up your stash. Whatever the best method is for each seed type, sowing 1/4 of your stash that way will probably produce as many of that plant as you need. You can afford to "experiment" with (waste) the other 3/4 of your seed. It may surprise you to find some easier or more productive methods if you experiment.

- Sow 1/4 now and hope they can establish themselves before frost.

- Winter-sow 1/4 of the perennials seeds in covered tubs or jugs, especially any varieties that you want to be sure you get lots of. Consider looking up each species that you saved seed from. If that seed germinates faster, easier or more completely with cold-wet stratification, winter-sowing is the easiest way to get high germination rates.

- Sow 1/4 later, like early spring, (whenever experienced gardeners suggest you have good odds for a "mix" that might include perennials, annuals and biennials, as many mixes do).

- Save 1/4 of the seed for the year after and for trades. If you keep track of which mix was sown in which spot, you can take a photo and say "this mix produced these flowers in the first year". Also, this year will show you the which are good ways to sow each variety or mix. Next year you can have the same success rate with 1/3rd the effort.


- Some seeds like poppies can be surface-scattered just before snow or even on top of snow! If you have poppy seeds or a poppy-rich-mix, give them what they like.

- big, hard seeds need a pre-soak and probably benefit from scratching. You might even sieve them out of mixes so you can give them a head start!

- Any saved seeds from varieties that you especially like are probably worth some extra effort. Set aside as many as half of those favorite seeds and look up the recommended method for each species. For the next few years, start at least a few of each favorite variety in the ways that are recommended most for that species. If they are perennial or reseed well where you live, you only need to succeed for one year to have a permanent patch. And now you know how to re-start that patch from saved seeds.

On the zinnias at least, I would wait to sow them till early spring. I've been growing them from seed in a similar zone for several years and almost never get volunteers. The cosmos should do fine; I haven't planted them deliberately for several years and I still keep finding them (and always in places I don't want them! ). The petunias should do ok, too, although as many as I plant, you'd think I'd have them popping up everywhere.