Posted: 23/01/2015 at 22:05
I've done this quite a few (!) times. A lot will depend on when your plant sale will be.
Firstly, much as we gardeners think that home-raised perennials sold at a plant sale/summer fete or whatever are a bargain over the high price at a GC, the average punter tends to ignore such choice plants. If you like, they are looking for plant bling.
The easiest and most profitable sales come from annual plants raised from seed - think French marigold, cosmos daisy, alyssum etc. Or cuttings from pelargoniums etc. And the greater profit comes from ready-planted pots/tubs/baskets.
By all means get as many parents involved as possible (especially if they are doing stuff in their own GH - a few extras for the school are easy for them when they are pricking out seedlings) and see if local GCs would get in on the act. They may be able to donate a basket or two etc. Or a couple of bags of compost.
Check the price at the GC and price yours just a bit below, but don't try to be too clever - the pricing strategy has to be right. And if you can produce plants in flower, punters will buy. We know that "buds are best" ie future flowers are better than soon-to-fade flowers, but the impulse buyers rarely does - which is why GCs put full-flowered plants out in great number to attract the eye rather than the brain.
Well, this has been my experience - I hope it goes well for you!