The little non-climbing convolvulous minor (such as Royal Ensign) can be sown much earlier....but the climbing Heavenly Blue morning glory really will be OK if you hold fire till the nights are absolutely frost-free (which, in Yorkshire, can be as late as the end of May). The suggested sowing times on seed packets often assume you are using heated germination aids and extra lighting. I have 2 main sowing periods for annuals, including veggies (apart from the perennials which are sown all over the place). March, for the hardy types (cornflowers, poppies, sweet peas (although I do a lot of these hardy things directly into the soil in autumn)agrostemma, calendula) and May for French beans, zinnia, cosmos, tagetes, dimorpotheca. ursinia. I start my tomatoes between 15th March and 1st April. I will use a cold-frame for some things (such as the dahlia tubers) but in general, I wait for annuals till the weather is good because they catch up easily.....and I hate that hardening off, bringing them in, taking them out, moving around stuff.

Sounds an awfully lot like what is called 'damping off', a term we use to identify any number of fungal disorders that result in the death of seedlings. But the problem could simply be cultural. The causes for seedling death can be complicated...sort of like putting a jigsaw puzzle together; if one of the pieces is missing, we don't get the whole picture. Excess moisture is the most obvious explanation. Is it as simple as watering too frequently? The consistency of the potting medium can also come into play...some are so slow to drain that the medium stays saturated for long periods of time, which suffocates (literally) the root system of the seedlings. Most seedlings grown on sunny window sills don't receive enough light, especially if the plants are full-sun species. The stems become elongated (leggy) and weak and exceedingly prone to collapse. Were your seedlings leaning sideways to reach for the sunlight? I think that you will find that most of keep our seedlings under a lighting system until they are ready to be placed outside. Can I assume that you don't have these plants on a heat mat? Seedlings need to have the heat mat off as soon as they germinate. If you give us some more information, perhaps we can be of more help. What kind of propagation mix, containers, lighting set-up (if any), heat (if any), etc.

Great post!. I also want to echo my thanks. Last year I was reading over a few posts about germination methods and advice as I was starting my first set of peppers indoors. All but one type of seed germinated at near 100% germination and very few died off (that said I was pretty obsessive about checking my seedlings :)) The greenhouse worked well and I had a very successful crop of peppers and tomatoes that I've never had success with in this climate before! The only significant error I made was some over watering of some of my tomato plants. The over watering was somewhat comical as I thought they were drooping from lack of water so I added more. I think I learned that if the soil is ummmmmm saturated they can't be lacking water LOL. I am still enjoying my pepper sauce as well as some frozen chopped up peppers for egg scramblers and fresh tasting salsa in Feb! Thanks again for all the advice given to newbies over the years!

Since the two you listed are both conifers, you could ask on the conifer forum. There are a fair number of folks who do their own reproduction.