Flower bulbs can’t be beat for bringing bursts of color to the garden. And they do it in such delightful fashion – their shoots thrusting up almost magically from the seemingly unoccupied ground in sudden crescendos of bloom. Then, just as suddenly, they pass from the scene, returning to the ground to wait out the months until their next brief fling.
Most garden bulbs (which botanically speaking comprise plants that grow from tubers, rhizomes, corms, true bulbs, or other underground storage organs) owe their fast and furious above-ground lifestyle to the short growing seasons that prevail in their native haunts. Many hardy “bulb” species, for example, hail from regions that receive most of their annual precipitation from late fall to early spring. The steppes and uplands of Central Asia – the ancestral home of many garden bulbs – are a place of long dry summers, cold bitter winters, and brief springs. Long, arid summers also characterize the climates of the bulb-rich Mediterranean and South African Cape regions.
Other bulb species are native to localized plant habitats that experience seasonal shortages of moisture or sunshine. Deciduous woodlands are the spawning ground of many of the most familiar shade-loving bulbs, which complete their above-ground growth in early spring before the canopy chokes out rain and sunlight.
Whatever their land of origin, most hardy bulbs need relatively moist, cool to cold winters and relatively dry summers, developing their roots in late autumn and winter and putting in an above-ground appearance for only a few weeks in spring or fall. Frost-tender bulbs, on the other hand, often come from regions in which rainfall and growth are concentrated in summer.
This is something to keep in mind when placing bulbs in the garden. Of course, a massed annual bedding display of hybrid tulips or hyacinths can be great fun and will work in just about any reasonably good soil. But a perennialized planting of less highly bred bulbs, artfully deployed in the appropriate garden habitat, can be equally compelling. Any garden niche that roughly mimics the conditions of a Central Asia steppe or a
Mediterranean chaparral or a temperate forest understory is fair game for a scattering of naturalized bulbs, which mingle beautifully with herbaceous and woody perennials that derive from the same natural habitat.
Reticulated irises (Iris reticulata and its hybrids) and “species tulips” (such as Tulipa humilis) make natural companions for penstemons, dwarf campanulas, plumbago (Ceratostigma plumbaginoides), low sedums, and other perennials that occur naturally in rocky steppe habitats. Likewise, crocuses, colchicums, cyclamens, and tuberous anemones look right at home with lavender, perennial candytuft (Iberis sempervirens), shrubby sages, and other small shrubs from the Mediterranean. And just about any partly shaded garden niche could benefit from a colony of woodland bulbs such as corydalis (including Corydalis solida) and trout lilies (Erythronium spp.).
A sunny garden site that dries out somewhat in summer is likely to be favorable for most sun-loving bulbs. In areas that are subject to summer rain and humidity, a well-drained soil works best. Rock gardens and troughs; embankments; wall plantings; sandy berms – all are ideal locations for grape hyacinths (Muscari spp.), ornamental onions (Allium spp.), and other steppe and Mediterranean natives. Quite a few sun-lovers (including many fritillaries and irises) absolutely require a dry summer rest, rotting away in warm moist conditions. Conversely, most woodland bulbs are relatively unfussy, thriving in just about any partly shaded site.
Whatever their favored exposure, bulbs tend to do best in relatively rich soil, and will usually benefit from a sprinkling of high-potassium fertilizer in early fall or spring. For excessively dry or heavy soil, incorporate a good amendment for fertility such as Fafard® Sphagnum Peat Moss and/or Compost. A general rule of thumb is to plant bulbs at a depth of 2 to 3 times their diameter (from the soil surface to their tips). Bulbs (such as crocuses and tulips) that are favorite morsels for chipmunks and squirrels may need protection such as a hardware cloth barrier (or interplant them with bulbs that rodents tend to avoid, such as narcissus and alliums).
The right bulbs in the right place will add a seasonal spark to any garden. Plant some this fall to reap your reward next spring, and beyond!