There is a web page here with step by step instructions (with photos) about how to grow tomatoes upside down. I’ve mentioned special planters before which help you do this but it is quiet simple to make the planters yourself out of buckets. Simply drill a hole in the bucket’s bottom and lid, wait till the plant is about 12 inches and then turn upside down  and hang from something that’s strong enough. Growing tomatoes upside down is fantastic for those who have little yard space and it also saves you from having to tie the plants to anything to keep them upright.