I agree with Laurie & Ace, particularly about the fertilser.
Think of it this way: Initially there are no roots or leaves to take up any fertilser, then when these (roots/leaves) do appear it is unlikely the fertiliser will be taken up because of light levels and temperature.
Then there is the issue that may occur if they do take lots of feeding on board at this timeof the year, the plants may become soft and lush, and then are more susceptible to frost,disease and of course they will be more of an attraction to wild life.
I will indeed try to grow some in pots for next year
There is still plenty of time to do that now!