help wanted fine seed sowing

planted two trays of seed, very fine seed saxifrage, and lobelia, both seeds like dust, sown them on top of compost over a month ago on window sill says do not cover seeds and keep them moist, have done this and have got absolutely nothing from both packets?
am I doing something wrong?

 

Prob too cold thriftybri. Sow again now it is much warmer. Not too moist either

 

Did you cover the pots though?
With that kind of stuff I dont cover the seed, but I do cover the top of the pot.

These kind of seed are so tiny that should they germinate and the surface of the compost even dries out for a couple of hours the tiny plants die.

I've never grown saxifrage from seed, but just wonder if it needs stratification.
Lobelia, I have, it usually comes up easily but grows fairly slowly in the initial stages.

Of course there is always the chance that the seed was rubbish, come across that quite often as well, myself.

 

Hi thriftybri, I sowed, Toms, Cucumbers, Purple Sprout Broc & Lobelia on 1st April, all apart from Lobelia are doing great (5/6 inches tall) The Lobelia are just showing, so give it time.

 

sown inside on window sill covered with a top on try still nothing

 

mr fothergills seed says nothing about stratification on packet

 

When sowing fine dust like seeds I mix with a little silver sand and sow on the top of seed compost . I lightly cover the seeds with vermiculite and use a lid on the tray. Note as John558 states , germination takes 5 weeks . I don't grow Lobelia from seed , just buy a tray of plug plants is far less fiddly.

 

When I was young
I used to prick out Lobelia singly, I could see pretty well in those days and my fingers worked.

It is surprising how one little seedling can grow to make quite a large bushy plant, if left alone.

 

Plants that grow from "dust" seed always amazes me as well . Photo below is a Giant Redwood seed, the largest plant on the planet grows from this !

 

Got to agree @HarryS , over the years I've grown all kinds of trees and shrubs from seed, and it always amazes me how something really quite small can hold all the information required to grow into a whacking great big plant.

 

Lobelia seeds need a high and constant temperature for good germination. I always grow them in an electric propagator with the temperature at 21-24C/70-75F taking up to three weeks for germination.

 

This is the benefit of gardening forums such as Gardeners Corner. OK, yes usually the seed packet carries some instructions for sowing. These instructions are usually based upon experience gained through the various trial stages.
The forum comments help fill in what hasn't been written and often includes the hits & misses. I like the comment, of saving time and trouble. Buy a tray of plugs. Doing so no doubt helps, but the gardener, perhaps a novice will lose out on the experience. I liked the comment by Pete. Pricking out lobelia individually. I recall a student once pricking out alyssum, one by one. Thankfully since those days, cell tray are available.
Sorry. Memories. Usually very fine seed is mixed with, as our friend says, silver sand or even or finely sifted sand. Whether sowing in pots, pans or trays. Don't compress the compost/growing medium. Make sure the compost has been well watered and left to drain. Having sown the seed, it is beneficial to cover the pot, tray etc with a pane of glass. This will help retain moisture, however each morning, remove the glass, wipe dry and replace. If the glass begins steaming up then raise the glass to allow air circulation. Once germination becomes visible, don't be tempted to get the watering can out. Water and let drain by standing the pots/ trays in water of the same temperature as the greenhouse or growing area. I am sure you will obtain good results. Enjoy your gardening.