I am confused about whether there are plants that are too tender to allow winter sowing. It seems clear that plants such as tomatoes that die in a fall frost can still be winter sown, in part because I know their seeds will sprout after a cold winter in the bed where the grew the prior year, and in part because others have told me they are good for winter sowing. But I understand impatiens do not winter sow well, although they are sometimes hardy in my region.
So my question: Are there some seeds that will not survive winter sowing because they are "tropicals?" What about "tender" perennials? Can all annuals be winter sown, or are some too "tender"? I am sure there is a line, but I don't see where it falls.
Datura is considered a tender perennial/tropical. Mine drops it seeds and I'm finding it reseeding itself in the bed. Datura's wintersow beautifully, so give them a try. However, please note that Daturas, like their Brugmansia cousins are poisionous if eaten.
I wintersowed my "tender" perennials in late March/early April. Tropicals and annuals can be sown in mid-April. It's really depends on when you get the last killing frost in your growing zone. Once the danger of frost is over, plant those seeds!
happy--I find it counterintuitive, too, and seem to spend most of my time confused about those plants that are not 'hard core perennials' in my zone--the tropicals and the 'tender perennials', and the annuals, too. Basically what I did last year was plant these 'tropical' seeds in April (later than the others) as shirley recommends. It seemed to work out OK for me although maybe I will try them indoors under lights next spring to get a bit of a jump start on germination.
And I am particularly confused about Hibiscus! I looked up the link, shirley, and it looks like that particular hibiscus is an Okra?
Other hibiscus, with which I am more familiar, fall into another group and seem to be perennials in my zone 6. I bought two of 'dinner plate' style (perennial) hibiscus in August for my perennial garden thinking I could collect seeds and make more of them by Wintersowing but maybe, maybe not?
I think WSing some of these plants/seeds in this 'grey area' between hardy and not hardy perennials/tropicals requires some experience and trial and error. It will be fun next season to try some of these...
Here's my take on it. If a perennial is hardy for your zone it will WS. If an annual is considered hardy or if it consistently self seeds in your zone it will WS. I found last year, that seeds not hardy for my zone germinated, but then died during subsequent cold spring temperature dips. Those still have to be started indoors and put out after last frost. There are lists in the wintersown.org site, by zone, of seeds that have been WS successfully. I don't think those lists are all inclusive. You can always give a seed a try and see what happens.
I cannot WS Impatients in my zone, but it sounds like you might be able to in yours. The purpose of WSing is not to be able to grow plants that are considered tender, but rather to grow plants that are considered hardy in a more natural environment. The benefits are numerous, and include no dampening off, stronger plants that are more cold resistent than those grown under lights, a higher rate of germination and it's just plain easy to do compared to an indoor set-up. People who haven't had much success indoors, usually have no problem when it comes to WSing.
Any idea why Impatiens and Coleus would be hard to WS? I understand that they are -- but they would both seem like perfect candidates -- especially the Impatiens which will sometimes self-sow. Very mysterious.
Don't know why Impatients and Coleus are so finicky. You could experiment and wintersow half the seeds in early Spring and germinate the rest of the seeds indoors. If the ones outdoors don't germinate properly at least you will still have seedlings that you grew inside.
My experience is - if it volunteers, then it can be wintersown. I w/s impatiens, cigar plant, passion flower. If anyone is interested in checking out my website, I have an excel spreadsheet that has some great info on what w/s for various zones. It was created by another group of wintersowers from another website. http://www.lakehousecreations.com/winter_sowing.htm .