Cage grown potatoes require a well-draining, nutrient-rich bed for planting and setting down roots. Work the top 6 inches of soil in your cage location before installing the cage. Breaking up soil clods and adding compost improves soil quality and drainage. Applying a general-purpose, slow-release fertilizer to the soil before planting ensures the necessary nutrients are present for the developing plants. Work the fertilizer into the soil and water it well before planting.
The cage size determines the potato bed's size. An 18-inch diameter cage provides enough space for three or four potato plants. Make the cage from ¼-inch hardware cloth or chicken wire. Cut the desired length and form it into a cylinder. Use wire to secure the ends of the wire mesh together. The cage may blow over in strong winds if it isn't properly anchored. Stakes hold it in place after installation over the bed.
Plant seed potatoes in a cage just as you would in a traditional garden bed. Dig a shallow hole for each seed potato, spacing them 6 to 8 inches apart. Set the seed piece in the hole and cover it with 3 inches of soil. Water the soil as necessary to keep it moist but not so often that it becomes soggy. The soil inside the cage dries out more quickly than in a garden bed, since the soil is exposed to air on all sides. Fill the cage with more soil each time the potato plants are about 6 inches tall, leaving no more than the plants' top leaves exposed. Continue adding soil until the cage is filled or the plants start flowering, whichever occurs first.
Cage-grown potatoes are ready for harvest once the plants finish flowering and turn yellow and wilt. There's no need to dig up the bed. Remove the stakes and lift the cage off the potato bed. Knock the soil down into a mound. Sort through the soil by hand, removing the potato tubers, as you uncover them. The plants produce potatoes down the entire length of their long stems if properly watered throughout the growing season. This harvest method prevents damage to the tubers, since there's no need to dig and risk scarring the potatoes.