Info from Old House Gardens -
'In the SOUTH, you can bloom them successfully in the ground, where singles tend to do better and bloom earlier. Plant bulbs in early summer, in a hot, sunny spot with well-drained soil, 4-8 inches apart with about 2 inches of soil over their tips. Water once but unless it’s very dry wait till leaves emerge before watering again. Then keep soil moist and fertilize regularly. Tuberoses need LOTS OF SUN, CONSTANTLY MOIST SOIL, and PLENTY OF NUTRITION to do their best.
WINTER CARE — In zones 9 and warmer (lows to 20° F), tuberoses can be left in the ground year-round. Elsewhere keep them growing as long as you can in the fall but eventually reduce watering till the foliage dries up or there’s a hard frost. Dig and store as glads (see above; no need for a fungicide dip), or dry and store them right in their pot.
In the spring, dump out the rhizomes. Each will have produced a cluster of daughter bulbs. Experts say that once a tuberose bulb blooms, it won’t bloom again, but any of the daughter bulbs that have reached the size of your thumb or so will bloom, and often smaller ones will, too. So add new soil to your pot and either replant the whole clustered bulb-clump or break off the largest daughter bulbs and replant only them.
An even simpler way that works well for us is to just leave the rhizomes right in their pot the second year and water and feed them heavily through the summer. However, by the third year they will have grown too crowded and you must repot. No matter what you do, regular fertilizing is always important to assure re-bloom
