I bought some plants and until now, I have kept them on a windowsil. They
seem to be thriving I intend to plant them in a basket (the old type
shopping basket) using polystyrene as a base and I bought the kind of
compost used for hanging baskets.

Should I buy the gel thingies that hold in the water?

I bought tomato feed too. When should I begin to use it?

Apologies for my possible daft questions, but many thanks for any help!