Garden Rain Lily

The rain lilies of the bulb catalog: Mexican, Central and South American Zephyranthes and Habranthus that flush pink, white, yellow or copper flowers a few days after a summer storm. Easy, tender, naturalizing - and toxic in every part, with bulbs that look like shallots.

Plant the bulbs an inch or two deep in free-draining soil in full sun once the ground warms in spring, water them in, and then leave them to the weather - they bloom on rain, not on anything you do.

These are warm-season bulbs, so the timing is the opposite of a daffodil's: plant them in spring, once the soil has warmed, rather than in autumn. Set the small bulbs one to two inches deep and three to four inches apart in full sun — they take light afternoon shade but flower less for it — with the neck just below the surface, and water them in. Unlike the native Atamasco lily, which is a plant of moist meadows, this group wants soil that drains freely: ordinary garden soil, a raised bed, or a gritty potting mix all suit them, and heavy ground that stays wet through winter is the one thing that reliably kills them.

Bulbs bought at flowering size often bloom their first summer; small offsets spend a year building up. They are outstanding container plants, and a crowded pot flowers better than a sparse one, so plant them shoulder to shoulder — a pot is also the standard way to grow them north of their hardiness, since it can be moved somewhere frost-free for the winter. In effectively frost-free zones 9 to 11 you can plant in autumn as well. The bloom trigger is rain: a deep soak after a dry spell brings a crop of buds up together and they open three to five days later, which is why a hose used the same way — hold off for a couple of weeks, then drench them — can be used to schedule a display for a particular weekend.

Almost none: soak them and then let them dry out again, feed lightly for more flushes, leave the foliage until it yellows, divide every few years, and mulch, lift or pot them where winter freezes hard.

Watering is the only technique that really matters, and the trick is to water the way weather does. Rain lilies flower on the contrast between dry and wet, so a plant kept evenly damp all summer makes leaves and sulks, while one that dries out for a week or two and is then drenched throws a flush of flowers a few days later. Give them a deep soak, let the top of the soil dry, then soak again. A light feed of a balanced or bloom fertilizer every few weeks through summer keeps a container clump flushing; in open ground they rarely need anything at all.

Let the foliage stand until it yellows and dies back on its own — it is what refills the bulb for next year — and never mow or shear it while green. Deadhead spent flowers for tidiness, or leave the pods and let them seed. Clumps improve for several years and then flower less as they crowd, so divide every three or four years in spring. Two safety habits go with this plant: every part of it is toxic, so it belongs away from grazing animals, dogs that dig, and small children; and the bulbs look like shallots, so label them and keep them well away from the kitchen and the onion bed. In winter, mulch at the cold edge of hardiness and lift the bulbs or move the pots beyond it.

Not a harvest plant - everything on it is toxic, so nothing is picked to eat. The only thing worth collecting is fresh seed, and the flowers feed small bees while each flush lasts.

There is nothing to harvest here. Rain lilies are ornamental bulbs and every part of them is poisonous — bulb, leaves, flowers and seed all carry the same amaryllis-family alkaloids as daffodils. The part that matters most is the bulb: small, rounded, brown-skinned and necked, and people have eaten them believing they had a shallot or a spring onion. Nothing about the plant is food, and no amount of cooking makes it so.

The one thing worth collecting is seed. Pods swell within days of the flowers going over and ripen in about three to five weeks, splitting into three parts to show stacks of flat, papery black seeds; catch them just as the pod turns papery and begins to open. Z. candida, Z. citrina and the Habranthus set seed freely, while many pink Z. carinata plants sold in commerce are sterile and set none at all. The flowers themselves feed small bees and the occasional butterfly during each flush, which along with the show is the whole return on the plant — the stems are far too short and the flowers too fleeting for cutting.

Nothing to store as food. The bulbs store themselves in the ground where they are hardy; elsewhere overwinter the pots dry and frost-free or lift the bulbs, and sow saved seed fresh rather than keeping it.

Nothing on this plant is stored for eating. As bulbs, they do their own storing: the bulb is the storage organ, and within their hardiness they simply stay in the ground year after year, thickening into clumps. Where winter freezes harder than they can take, treat them like any tender bulb — either grow them in pots that spend the winter in a frost-free shed, garage, or cool room, kept nearly dry until spring, or lift the bulbs after the foliage dies down, dry them off, and store them in paper bags or dry peat somewhere cool and frost-free.

Two storage rules are worth spelling out. Label everything, and keep bulbs nowhere near food — a paper bag of unlabelled brown bulbs in a kitchen drawer beside real shallots is precisely how these come to be eaten by mistake. And do not dry-store the seed: rain-lily seed is short-lived and germinates best fresh, so sow it within a few weeks of collecting rather than holding it until spring. If you must keep it briefly, keep it cool, dry, and labelled with the species, since the seedlings of these species are indistinguishable from one another.

Fastest by splitting the offsets a mature clump makes; fresh seed is easy too and flowers in two to three years, though many pink Z. carinata plants are sterile and never set any.

Offsets are the usual route, and the only one that keeps a named clone true. A happy bulb makes daughter bulbs around itself, and a three- or four-year-old clump lifts as a tight cluster you can pull apart with your fingers. Do it in spring as growth begins, or straight after a flowering season, replanting the pieces at the same depth and watering them in; a clump split this way usually flowers again the same year or the next. It doubles as the fix for a crowded planting that has quietly stopped blooming.

Seed is easy where the plant sets it. Collect the flat black seeds as the pods turn papery, and sow them fresh, barely covered, in a gritty mix kept warm and moist; germination usually comes in two to three weeks, and seedlings reach flowering size in two to three years. Z. candida, Z. citrina and Habranthus seed freely and often self-sow into the ground around them, while many of the pink Z. carinata plants in commerce are sterile and never set a pod — and hybrids do not come true from seed even when they do set one. Bulbs will not root from a leaf or a stem cutting, so offsets and seed are the only two ways.

Nineteenth-century imports from Mexico and the Rio de la Plata that became the rain lilies of warm gardens worldwide, naturalizing in Gulf-Coast lawns and picking up the American natives' common names on the way.

The garden rain lilies came out of the great nineteenth-century flow of American bulbs into European horticulture. Zephyranthes candida was described from the grasslands of the Río de la Plata in Argentina and Uruguay, where it grows thickly enough in damp meadows to whiten the ground; Z. carinata came from Mexico and Central America and reached gardens under the name Z. grandiflora, which is still on half the labels sold today. The genus name is Greek — Zephyros, the west wind, plus anthos, flower — while Habranthus, a separate South American genus, means roughly ‘graceful flower’ and is told apart by flowers held at an angle rather than straight up.

They travelled well. Cheap, tough, and quick to multiply, they were passed over garden fences across the Gulf South, the Caribbean, southern Asia and Australia until they turned up in old lawns and cemetery plots far from anywhere anyone remembered planting them, and in many warm countries they are now thoroughly naturalized. Along the way they inherited the common names of the American natives they resemble — rain lily, fairy lily, zephyr lily — which is the root of the confusion this page exists to clear up. A ‘rain lily’ from a bulb packet is almost never the Southeastern native Zephyranthes atamasco, and planting one is not a native planting.

Leaves but no flowers usually means steady watering, too little sun, or a crowded clump; winter losses are cold or wet soil; and the bulbs must never be confused with onions or shallots.

Plenty of leaves and no flowers: the most common complaint, and usually the watering — a plant kept evenly moist grows foliage, while one allowed to dry out and then drenched flowers. Too much shade, a crowded clump that needs dividing, or a seedling under two or three years old will do it too. It flowered once and then stopped: normal. The flushes follow soakings, so the next storm starts the next one. It came up late, or not at all, in spring: these are warm-season bulbs and wait for warm soil — give them time before you dig, then check for cold damage or rot. Bulbs soft when lifted: waterlogged ground; move them somewhere free-draining or into pots. Nothing returned after winter: cold, wet soil, or a species less hardy than the label suggested — mulch, move to a sheltered spot, or overwinter pots frost-free. The leaves look like weed grass: they do, all year; mark the spot so nobody mows or weeds them out. Is this a native plant? No — these are Mexican, Central and South American species. The Southeastern native is Zephyranthes atamasco, on its own page. Can I eat any part of it? No. Every part is toxic, and the bulbs resemble shallots closely enough that they must be kept away from the kitchen, and the plant away from children, pets and livestock. Pests: few worth the name.

Warm-climate bulbs for roughly zones 8-11, with Z. candida and Habranthus robustus the hardiest at about zone 7; cold and winter wet are the limits, and everywhere colder they are grown as pot bulbs.

These are subtropical bulbs, at home where summers are long, hot and humid and winters barely freeze. Zones 9-11: ideal — they stay in the ground, flush after every summer and autumn storm, and Z. candida holds its dark rush-like leaves right through the winter. Zone 8: reliable for most of the group with the bulbs a little deeper and a loose winter mulch; foliage burns off in a hard freeze and comes back. Zone 7: the edge, and species-dependent — Z. candida and Habranthus robustus are the ones that usually come through with sharp drainage and mulch, while Z. carinata, Z. citrina, Z. rosea and most hybrids are better potted or lifted. Zone 6 and colder: pot culture only, moved somewhere frost-free for the winter.

Hardiness figures for this group are unusually unreliable, partly because catalogs quote one range for a genus spanning everything from an Argentine grassland plant to a Caribbean one, and partly because winter wet decides as much as winter cold: the same bulb that shrugs off 15°F in gritty raised soil rots at 25°F in heavy clay. Buy by species rather than by the words ‘rain lily’, plant into ground that drains, and where you are unsure keep a few bulbs in a pot as insurance. Heat, humidity and drought give them no trouble at all — the summer that flattens other bulbs is exactly what these were built for.