Q. I would like to grow some unusual bulbs in containers this summer. What are the basic guidelines to ensure good growth?
A. Late winter or early spring is a good time to consider the wide range of exotic bulbs available for container planting. Summer-flowering annual bulbs are colorful and unique choices for containers. These include bulbs, tubers, corms, rhizomes such as lily of the Nile (Agapanthus), montbretia (Crocosmia), tuberous begonia (Begonia x tuberhybrida), garden canna (Canna x generalis), caladium (Caladium), elephant ears (Colocasia), calla lily (Zantedeschia), peacock orchid (Acidanthera) and tuberose (Polianthes). By starting these tender bulbs indoors, they will have a head start before being gradually introduced to balmy outdoor conditions. After May 15 the containers can take up permanent residence outside.
Most bulbs prefer a good commercial potting soil with some added organic matter and sand. Plant the bulbs shallow, 1 inch below soil level, except for tuberous begonias, which are only partially covered with soil. Crowd the bulbs closely in a heavy container able to withstand windy weather. Correct watering is critical with bulbs. Water when the soil feels dry to the touch (unless otherwise specified). Bulbs rot in soggy, overwatered conditions. Provide indirect light until active growth appears, when most bulbs prefer full sun (again, not begonias). Rotate the pot to ensure even growth. Fertilize with a dilute balanced 15-15-15 solution.
Bulbs must have a dry, dark, dormant season. During fall, dig the bulbs up, remove all foliage and dirt and dry in the sun. Store in loose peat moss or vermiculite in a cool, dark place during winter. Some gardeners store the bulbs in their containers in a very cool porch. Do not water during winter. Many bulbs will signal they are ready to grow again by initiating growth early next spring. Plant them immediately.