Growing tomatoes upside down appears to be a bizarre trend when in actuality it is an ingenious way to conserve space while growing fresh tomatoes in a small area such as an apartment balcony. There are also many benefits to growing tomatoes upside down; an increased fruit production because of better air circulation to the leaves and better absorption of nutrients by the roots from watering and fertilizing from the bottom up, plus no staking is required and your plant will have fewer problems with diseases that are more common when grown directly in the ground.
Drill a hole in the bottom of a five-gallon bucket if there isn't already one. It should be about 3 inches in diameter.
Remove the tomato plant from the container it came in and gently loosen the roots. Remove all of the leaves except the top set.
Reach inside the bucket, carefully insert the top of the plant through the hole of the bucket; only about 2 inches of the top of the stem should be showing through.
Hold the plant by the roots on the inside of the bucket and carefully put enough peat moss inside the bucket to cover the roots completely. Pack down gently so the plant is secure.
Fill the bucket with potting soil to within 1 inch of the rim. Firm the soil with your hands.
Hang the bucket by the handle in a place that gets full sun daily and is high enough off the ground to allow for the plant to grow several feet.
Water the hanging tomato plant until the water runs out of the bottom. Check the level of the soil after watering. If it has settled more than one-inch below the rim of the bucket, add more soil.
Apply fertilizer one month after planting using a water soluble liquid food that is lower in nitrogen (e.g. 5-10-50). Too much nitrogen produces abundant foliage, but less fruit. Another application of fertilizer can be done one month later. That should be enough for the season.
Prune your tomato plant only to keep it under control if it grows too large. Cut off the top of the plant to encourage more lateral growth instead of vertical.