Is failure possible?
I would say, honestly, that the answer is yes. I've been Winter Sowing for a few years and there has always been a few flats that haven't germinated. And it's not always because of choice of seeds. Let me see if I can come up with the most common causes.....
I trade for my seeds and once in a while I am trying to grow something that I later on find out is genetically sterile or the seeds weren't gathered properly. I'm very forgiving because I once was a new trader too and I have no doubt that I may have traded seeds that weren't 100%. I learned by example and got better as I went along.
Another reason could be that a flat has dried out at a crucial point due to my negligence. It's easy to tell when a flat needs water because you don't see condensation under the lid. If I'm away for a few days during Spring and can't be home to check on the soil moisture then a flat could perish. I've since solved that problem by nestling my flats down into a kiddie pool with about an inch of water in it. The kiddie pool is placed in the shade to reduce evaporation from direct sunlight. The flats soak up the water and they're fine while in the pool....I don't have to worry about them drying out. When I get back home I take out the flats and dump any remaining water inthe kiddie pool. I store it upside down when I'm not using it as I don't want it to become a breeding ground for mosquitos.
A flat has overheated. I lost several flats last year because of a freak heat wave in early Spring. I was away and unable to get home for several hours. If I had been home I could have increased the ventilation slits and that would have allowed the overly-warmed air to vent away.
I've pushed the envelope and tried to germinate a tropical plant. I ALWAYS try a few tropical varieties each year. Winter Sowing is best for plants that originate in a temperate climate (a temperate climate is a region that has four distinctly separate seasons.) Sometimes I am quite surprised by my successes and sometimes I am not surprised by my failure. It's yin and yang and I take the failure whimsically....I don't get hung-up or depressed about it. I've been delighted to germinate a beautiful crop of annual yellow hibiscus that are regional to South East Asia. My success with coleus has been minimal...I had just a few seeds germinate...I loved what did germinate but I wished I had gotten more.
A flat simply doesn't germinate despite having all the criteria for germination. Mother Nature is in control....was there some inferiority to their genetics that didn't allow them to germinate? Anything is possible....and again I don't get frustrated over it.
Usually, we can expect very high germination percentages across the board....a large amount of the flats will germinate (my own percentage of success has been routinely about 90%...this could go higher if I stuck with only temperate climate seeds) and also, among the individual flats the germination inside the flat is super-high too. The flats protect the seeds from the elements, critters, wash-outs from downpours, and desiccation from wind...so there is a higher germination count simply because more seeds survive the winter to germinate when the weather warms. This is the main reason why Winter Sowing is superior to direct sowing, IMHO*.
*IMHO ~
In My Humble Opinion
I hope everyone will have tremendous success and I do expect it as well....but it is important to realize that some failure, minor though it is, should be expected.
Winter Sowing is only as perfect as Mother Nature. We must take the bitter with the sweet, but that sweet is very sweet!
Tip suggests these links for further study.
by Wone-Yoke Lao
Areas Important to Women's Succes in Computing
Department of Computer Sciences
University of Texas at Austin
University Counseling and Consulting Services
University of Wisconsin
Virginia Cooperative Extension
Virginia Polytechnic and State University
Virginia State University
