A small garden doesn't mean you have to skip veggies such as potatoes (Solanum tuberosum) that traditionally hog ground space. A potato tower allows the tubers to grow up through a soil-filled cylinder to produce more potatoes in the same amount of ground space as a single hill of potatoes. After some minor construction initially, your vertical garden supplies potatoes for the whole family with minimal effort.
Potatoes grow underground, so you need a tall structure to support the soil for vertical growth. A tall cylinder design works best for the potato tower. Use a variety of materials to create the structure. Chicken wire and bamboo fencing both work well as the outer wall of the tower. An old tomato cage is an option for creating the cylinder shape. Wrap the outer wall material around the cage. Another option is to form the cylinder shape from the chicken wire or fencing between 18 and 24 inches in diameter, and use additional wire to hold the shape. Rebar stakes pounded into the ground give stability to the tower.
With the potato tower structure secured in place, you're ready to plant the potatoes. Use certified disease-free seed potatoes for planting. You want at least two eyes on each seed potato for the best results. The seed potatoes go around the inside perimeter of the tower structure, with about 4 to 6 inches between each one. Potatoes grow well in a variety of soil conditions, as long as it is well worked so it is loose and drains well. Adding compost to either garden or potting soil creates a nutrient-rich filler for the potato tower. You need to cover the potatoes with several inches of potting soil and compost mix to protect them from the sunlight and to give them a place to grow. If you used chicken wire to build the structure, layering straw inside the tower helps hold in the soil.
As the potatoes grow, you need to add more soil to the tower. Add another 3 to 4 inches of soil each time to increase the growing space available for the potatoes. You also need to keep the potato plants watered well -- about 1 to 2 inches weekly between your irrigation and rainfall. A tower higher than 3 feet tall is often difficult to keep adequately moist since the water has to reach all the way to the bottom. You will notice the soil drying faster when you grow the potatoes vertically in a tower, so more frequent watering is necessary. Water is most important while the potatoes flower. You can stop watering the plants when they begin to die off.
The visible part of the potato plant signals when the vegetables are ready for harvest. The plant starts to die off as the potatoes reach maturity. Early harvests give you smaller potatoes, while waiting results in larger spuds. If you're not sure when to harvest, dig up a few tubers near the top to check on the size. When you're satisfied with the crop, you can easily harvest the potatoes by taking apart the tower. As the soil falls, all of the potatoes become visible. Kids can help by grabbing the potatoes out of the soil.