GROWING MINIATURE BULBS OUTDOORS
Tender, summer-flowering bulbs are planted in late spring, when soil is warm and danger of severe frost has passed. Hardy bulbs are usually planted in late summer and early fall, when foilage has ripened and died back and the plants are in deepest dormancy. This includes fall-flowering types like the colchicums. The earlier bulbs can be planted, the stronger the root systems they can develop before winter, and the stronger their flowering during the first season.
Make sure the selected site has perfect drainage. Bulbs rot quickly when water stands around their roots. Dig generously, to about eight inches deep; enrich the soil with organic matter such as leaf mold or compost; increase aeration and drainage in sticky, clay-like soils with sharp sand; add a light sprinkling of bone meal or superphosphate, if fertility is low. Since few bulbs like very acid soil, lime is a “must” except where the soil tests so extremely alkaline that the addition of organic matter does not make it acid.
An average measure for depth of planting is twice the diameter of the bulb in cooler climates, an inch or so deeper in areas like southern Virginia to provide protection against summer heat. For quick effect, plant about a dozen bulbs in a group; six bulbs more widely spaced will usually increase and give the same effect in several years.
Watering
Most bulbs need moisture before, during, and after flowering, when foliage is green and growing or ripening. They’re better off on the dry side during dormancy. This is a perfect setup for most hardy types, because they need the least watering in summer, when droughts are most common. But it does increase the urgency for perfect drainage for some of the Western species that can’t bear moisture in winter.
Fertilizing
Except for an early-spring top-dressing of leaf-mold compost, we seldom feed our little bulbs. Occasionally, some healthy specimens may get a puny, undernourished look that calls for sprinkling bone meal or superphosphate over the soil and scratching it in. Or we may water with manure “tea” during or after flowering time.
If soil is properly prepared at planting time, supplemental feeding should not be necessary for most types for several years. By that time some bulbs have multiplied so enthusiastically they should be lifted, separated, and reset in freshly mixed soil.
Problems and Pests
If you plant bulbs where they don’t stand in soggy mud or water, you’ll have little loss from rot. But if you’re in a suburban or rural area inhabited by cute chipmunks, squirrels, or mice, you won’t want to plant juicy morsels such as tulips, crocus, and eranthis just to feed the animals. I’ve never had the time or patience to plant bulbs in wire cages. Poison baits can be dangerous when you have children or pets. An effective safety measure is to put the bait inside a clean milk bottle and cover it with a heap of straw or leaves, with evergreen branches to hold the heap in place.
Winter Protection
Because the root systems may not be completely matured, newly planted bulbs should be mulched with a light, airy covering of something like salt hay during their first winter. After that, the necessity for protection varies with hardiness and with climate. Sometimes these mulches hold in more moisture than is good for bulbs. If alternate freezing and thawing should heave the shallow roots up through cracks in the soil, press them back gently but firmly and cover with soil again.