Seed germination

I'm wondering what is wrong with my seed growing this year. I check for new seedlings every day, but I have 2 trays of seeds that have appeared overnight and are already leggy [Verbena bonariensis and Impatiens].
They are in unheated trays with plastic covers in the greenhouse. The covers are quite old, is it possible they're not letting enough light in? Another possibility is that the green house isn't light enough, it isn't ideally positioned but gets lots of light in early morning until mid-day then is in dappled shade.
Help please? :(

 

You are lucky liz, my verbina bodnariensis is not showing after weeks!

 

i don`t know what happened to the verbena i sowed. i only got two leggy things.

 

I germinate impatiens at 22c and get good germination, about 85/90%, they will be slower at lower temperatures. They (the seed producers)used to recommend sowing uncovered but now a thin layer of fine vermiculite is suggested so a fairly light position is needed.

 

I would not worry Liz. I grew some Cosmos last year, it shot up abour 4 inches in 4 days, then just sat and did nothing for quite a while. Anyway Verbena is leggy. I grow all my seeds inside the house, and they must get less light than your greenhouse, but I have never had any problems.

Waco, you could try putting the Verbena in the fridge for two weeks. It is a bit of a devil. When I grew it three years ago, after a while I put it in the fridge, and when it came out it still did nothing for another two or three weeks. I was about to throw it away then suddenly one day all two thousand seeds germinated on the same day.

I am currently trying to grow three trays of Verbena (Hastata, purple Rigida and blue Rigida). Even after the cold treatment they are coming through very slowly, and I suspect that Strongylodon is right - they need a higher temperature.

 

I have one tray of Impatiens seed saved from last year which has not germinated at all, so I will put in the heated propagator.
The Verbena bonariensis came up nicely but now seem to be just sitting there, would they like more heat or are they slow?

 

Liz, if they have germinated OK I would tend to leave them. Plants tend to go leggy when they have too much heat for the available light. They judge the season by the temperature, and if its warm they assume the season is well advanced but that they are under the canopy of another plant. So they grow taller and taller trying to get above the canopy. I suspect it is a good thing to keep temperature and light in balance - ie natural.

Most books suggest heat to make certain types of seed germinate, but once germinated remove the heat.

 

I grow verbena venosa every year (about 500-1200 for the parks obviously) I have never given them any cold treatment only because I have never seen or read any advice on the subject. Half of the seed comes up in 2/3 weeks and the rest 2/3 weeks later ... very annoying trying to prick out half a tray and not disturb the other seed. I shall try cold treatment next year. As I said before we can all learn from this site. Thanks PeteS.