Harden off: Take your plant out of the box and be gentle with the graft. Set it in a bright, sunny area indoors, but not in direct sun just yet. Give it a drink of water. Over a period of a few days, gradually move the plant outdoors and back in if the weather is still chilly until it has acclimated to the weather.
Planting: Unlike most grafted plants, this one requires that you DO bury the graft. Plant it so the graft is a few inches below the soil level. Support the tomato as needed, and prune excess vegetation to allow the tomatoes to ripen.
Container: This plant can be planted in a large (minimum 22-inch) container, such as a half wine barrel or something of similar size. Make sure you can adequately hill the potatoes as they form.
Care: Transplant into a soft, loamy soil so the potato tubers have ideal conditions in which to grow. Offer your tomato-potato water and amendments just as you would for any other vegetable plant. Be sure to hill around the roots so the potatoes to do not turn green. Hilling means adding soil to increase the length of the stem that’s under the ground.
Harvest: Once you have been harvesting the tomato for a few months, maybe around mid-September, cut the tomato plant off. Hack it to about 4 to 6 inches above the soil level. This will allow the potatoes to begin ripening.
Potatoes: Allow the potatoes to ripen for seven to 12 days, then you can dig up the potatoes and harvest them as normal or leave them in the ground for several more days.