This contraption is something Vicki got me the other year and I find it quite handy for starting off your hanging baskets. In the one you see here I have three trailing Petunia's, I know it looks a bit sparse at the moment but these three plants will grow to fill the basket. Anyway what I like about these containers is that they're good for sitting on the greenhouse staging while bringing the plants on but once its time for them to go out in hanging baskets you simply put a bit of compost in the bottom of the basket and then drop this container with plants straight in to the basket and then the roots just grow on out though the bottom. In the picture there are three with Petunia's which are for a project I have planned for this summer and one with four trailing Tomato plants.
If you want to join in the Petunia project with me you need to get planted up three 12 inch (30 cm) hanging baskets with 3 trailing petunia's in each. Just plant them around the top of the basket and don't worry about fancy liners or trying to hide it as the plants will do that for you in no time at all, I line mine with an old compost bag cut to shape and with the black side facing out. If you have a greenhouse put them inside to bring them on faster if not then a warm sunny place outside will do and then in a couple of weeks or so I will show you what to do with them. Make sure you have one good strong hanging basket bracket in place by this time though. Also it will need to be a bit out of the way because the baskets will hang a bit low by the time we've done.