Agave ovatifolia
| Light | Full sun to bright light; tolerates some light shade |
|---|---|
| Water | Deeply but infrequently in growth; keep much drier in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Notably cold-hardy for an agave; hardy to about 0 °F (−18 °C), roughly USDA zones 7–11 |
| Propagation | Seed; bulbils from a spent flower spike; occasional offsets (see Propagation - offsets) |
| Toxicity | Sap and leaf tissue are irritating; the terminal spine and teeth can injure — keep away from paths and curious pets |
Agave ovatifolia, the whale's tongue agave, is a strikingly symmetrical, cold-hardy agave from the mountains of northeastern Mexico. It forms a solitary rosette of broad, deeply cupped, powder-blue leaves whose wide, gently spooned shape gives the species its common name. Among the hardier members of the genus Agave, it is prized by growers in cooler climates where most agaves will not survive outdoors.
Description
Agave ovatifolia grows as a single, tight rosette that can reach roughly a metre or so across and about half as tall, occasionally larger on well-established plants. The leaves are its defining feature: wide, thick and noticeably concave — cupped like a scoop or, indeed, a broad tongue — and coated in a chalky, glaucous bloom that ranges from grey-green to a vivid powder blue. The undersides often show faint impressions where the leaves pressed together in the developing bud.
Each leaf is edged with small marginal teeth and tipped with a stout terminal spine. The overall effect is a dense, geometric rosette that holds its form well and reads as sculptural in the ground or in a large pot. Like all agaves it is monocarpic: a mature plant eventually sends up a tall branched flower spike, blooms once, and then dies, typically leaving seed and often bulbils on the spent flower spike behind.
Distribution and habitat
The species is native to the limestone mountains of Nuevo León in northeastern Mexico, where it grows on rocky limestone slopes and grassland at moderate to fairly high elevation. That montane origin — with cold nights, seasonal rain and sharp drainage — is the key to its unusual frost tolerance and its preference for gritty, well-drained ground.
Cultivation
Agave ovatifolia is one of the more forgiving large agaves and an excellent choice for growers in temperate climates. Give it full sun to very bright light and a gritty, fast-draining mix or garden soil; sharp drainage matters far more than absolute cold when overwintering it. Water deeply but infrequently through the warm growing season, letting the soil dry between waterings, and keep it much drier in winter when wet, cold soil is the main danger.
In the ground it is remarkably hardy for an agave, shrugging off frost that would kill most of the genus, though a hard freeze on soggy soil can still cause rot. In containers it appreciates a heavy pot for stability once it bulks up, and benefits from being moved somewhere bright and dry over a cold, wet winter. See Watering and Repotting for general technique. Site it thoughtfully — the terminal spine and marginal teeth are sharp, so keep it clear of walkways and play areas.
Propagation
Propagation is chiefly by seed, sown on a warm, gritty surface and kept lightly moist until germination; see Propagation - seed. The species is characteristically solitary and, unlike many clumping agaves, seldom produces basal pups; a flowering plant instead sets seed and commonly forms bulbils (small plantlets) on the spent inflorescence, which can be potted up once rooted. Where offsets do appear — mainly on certain clones — they can be separated and rooted as for other agaves, see Propagation - offsets. Because the plant is monocarpic, collecting seed or saving bulbils and any offsets from a flowering specimen is the way to carry it on.
Cultivars
A number of selections are grown for leaf form and colour, including compact clones and forms selected for especially broad or intensely blue leaves, as well as variegated plants sought after by collectors. Variegated and unusually coloured forms generally grow more slowly and appreciate slightly gentler light than the plain blue species.
Common problems
- Rot — the main cause of loss, almost always from cold combined with wet, poorly drained soil rather than cold alone.
- Agave snout weevil — a serious pest of larger agaves; grubs tunnel into the core and the rosette collapses, often as it approaches flowering size.
- Pests — mealybugs and scale can hide among the tightly packed leaf bases; see Pests and diseases.
- Physical injury — the stout terminal spine and marginal teeth can scar leaves that rub against them and can injure people or pets, so give the plant room.
See also
- Agave — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation - seed · Propagation - offsets · Pests and diseases