Selecting a suitable tomato variety for upside down growing will increase your chances of success. Look for a plant that has been bred for compact growth and produces small to medium-sized fruit. No matter what variety you choose, keep in mind that growing tomatoes in an upside down hanging planter requires frequent watering. This is not only because tomatoes are primarily made of water, but also because the planters, with a relatively small amount of soil, can heat up and dry out quickly.
Tiny Tim matures in 45 days. A dwarf plant, it produces large yields of 3/4-inch cherry tomatoes.
Cherry Gold, the yellow version of the Tiny Tim, is another dwarf plant that produces cherry tomatoes.
Small Fry produces 1-inch fruit and is noted as especially good in hanging baskets, according to the University of Illinois Extension. This variety requires 72 growing days.
Red Robin is a miniature plant that produces an abundance of cherry tomatoes with a "real" tomato taste. It does well in a 6- to 10-inch pot, making it ideal for upside down gardening.
Pixie Hybrid II
The Pixie Hybrid II is a compact dwarf plant with 2-ounce fruit that matures in 52 days.
Early Girl produces tasty, uniform 4- to 5-ounce tomatoes. It requires 62 days for fruit to mature.
Saladette's long, narrow tomatoes are larger than cherry, but smaller than many garden varieties. These tomatoes tend to have less moisture, much like Roma tomatoes.
The Patio Hybrid tomato plant is rather compact. It reliably produces lots of tomatoes about the size of a tennis ball. In an upside down container, you can expect fewer tomatoes than if grown upright, but if the plant is thriving, you may have to provide some type of support for the plant. Keep an eye out for signs of possible plant stress from the weight of an abundant crop. Fruit on the Patio Hybrid matures in about 70 days.
Just as its name implies, the Toy Boy is a small plant with small fruit. It is frequently mentioned as a tomato variety good for basket growing.