Since the Topsy Turvy uses the upside-down gardening method, it is likely that you can soften the dirt in the container than from containers which sit on the ground. The planter hangs above most of the issues that contaminate soil, like fungus, weeds and pests. It is not entirely immune to those problems, however, so soften the dirt with caution.
When you buy the Topsy Turvy planter, it doesn’t include dirt. You buy the potting soil of your selection. Gardener’s Supply Company suggests a combination of sphagnum moss, peat, perlite and vermiculite. Deciding on a sterile potting mix initially gives you a much better chance of being able to reuse the soil the next year.
When the growing season ends, examine the plants and dirt in the Topsy Turvy carefully for signs of pests or disease. If you notice pests on your Topsy Turvy plants, discard the dirt because it likely harbors eggs. Do not reuse the dirt if the plant was not healthy at the end of the season; even after you remove the plant, the pathogens likely remain in the soil and can infect next year’s plants. One exception is blossom end rot. Topsy Turvy tomatoes tend to suffer from it if the dirt isn’t watered often enough, and it seems as a dark circle of decay at the bottom of the tomato. It is brought on by a calcium deficiency in the plant, not a fungus or other pathogen, so it doesn’t contaminate the soil. If you’re not positive a predicament is blossom end rot, throw away the dirt to be safe.
Many of the nutrients in potting soil either have absorbed by the plants or leached out as water drains out of the planter. Because of the upside-down design, water drains quickly and easily from a Topsy Turvy, so it may wash out a significant amount of nutrients. Prior to reuse soil in the Topsy Turvy, refresh it by mixing it with compost, using 1 part compost and 3 parts potting soil. Turn 1/2 cup of water-soluble, time-release vegetable fertilizer, such as a 5-10-10, into the dirt to finish preparing it to your next round of plants.
The dirt from the Topsy Turvy isn’t the one thing you’ll be able to reuse. Before you put away your Topsy Turvy, clean it thoroughly so you can use it again. Mix a solution of 1 part bleach to 9 parts water, then spray it on the inside of the planter, wipe it with a clean cloth and rinse it with water. If any debris doesn’t remove easily, rub it gently using a scouring pad. The bleach kills any pathogens which may infect the next round of plants.