The practice of growing tomatoes in 5-gallon buckets wins an official blessing from horticulturalists at numerous extension services. Tomatoes need a lot of root room, and the University of Maine Extension Service, among others, approves of the 5-gallon size, recommending tomato varieties for bucket growing including Patio, Roma, Sprite, Husky Red, Husky Gold and Husky Pink. You can hang the bucket, instead of sitting it on a patio or the ground, to better use outdoor living space and to avoid the need for staking.
Drill a 3-inch hole centered on the bottom of the bucket. Balance the bucket on sawhorses or similar surfaces so the hole is exposed.
Turn the bucket the right way up. Place a circle cut from newspaper or a coffee filter in the bottom of the bucket. Cut an X in the paper to permit the tomato seedling to pass through. Thread the seedling's leaves and stem through the paper so it hangs upside down through the bucket.
Add potting mix around the seedling root ball so that part of the stem is buried in the mix. Add 2 cups of compost to the bucket. Fill the rest of bucket with potting mix up to about 1 inch short of the top.
Carry the bucket to the structure where you plan to hang it. Use an S hook to hang it by its handle. Water the plant so to thoroughly soak the potting mix. Stop when water begins to trickle out of the hole.