At this time of year I order a few Plug Plants from a Gardening Catalogue. It often proves worthwhile and saves a lot of worry over Germination too. Things like Impatiens(Busy Lizzies) are very hard and slow to Germinate without the right conditions, so Its cheaper to buy them as Plug Plants and no wasted seeds.
Also Geraniums too are best done this way and again , are cheaper than buying the plants later from a Garden Centre. The photo on the left, shows these plug plants after they were transplanted Into trays. They will then grow on, until planting outside in late May or early June.
Other Than the plants named above, I usually grow the rest of my Flowers from seeds. Other than plants like Fushias, which again are best grown on from Plug Plants or from a nursery as young plants. I shall begin starting my seed sowing in February/March and the Greenhouse will be Insulated by Polythene(Bubble wrap), inside the glass. To stop Frost damage.
Also maybe a small Paraffin heater on nights that are due to be very Frosty Indeed.