Yucca is usually thought of as a desert or semidesert plant, confined to dry areas of the South and the southwestern desert, but several yuccas are surprisingly hardy in the cool, moist regions of the North.
Yuccas are very handsome plants. Nearly all of the 40-odd species have stiff, swordlike silver green leaves, growing in a clump at ground level. From this clump arises a single leafless stalk bearing a magnificent spike of highly fragrant, waxy flowers.
Yuccas blend handsomely in borders, contrast beautifully with the shapes of both evergreen and deciduous shrubs, and can be planted to stand as majestic sentinels on either side of an entrance gate or door. They also serve well lining a driveway, fence or terrace wall, or as a dramatic living sculpture against low, craggy rocks. Finally, yuccas can be grown in tubs and moved around for special effects.
Yuccas Planting and Culture
All yuccas require a sunny and fairly dry location with a light, sandy or gritty well-drained soil. Digging a deep hole and filling it with a sand-humus mixture will take care of this. Apply compost, bone meal and dried manure to the plants once each year. Watering should rarely, if ever, be necessary. Drought produces a lovely foliage and stem patina on desert-type plants. Yuccas generally flower only in alternate years, but the flowers last four to six weeks.
Yuccas are easy to propagate. They can be increased by seed, rhizome or stem cuttings, or by digging offsets from the side of an established plant.
In nature, the yucca is pollinated by a small white moth, the pronuba. This night-flying insect deposits her eggs in the seed vessel of a blooming yucca, and then fertilizes the plant with pollen from another yucca. When the pronuba grubs hatch out, they find a goodly supply of seeds to eat, but leave plenty to produce more yuccas. Scientists call the yucca-pronuba relationship a perfect example of symbiosis, the mutual interdependence of two things in nature.
Two species have trunks. The Joshua tree (Y. brevifolia) grows up to 40 feet high, its branches twisting into grotesque shapes. The Spanish bayonet (Y. aloifolia) is about 20 feet tall, and has very sharp-pointed, long leaves and spectacular white or purple-tinged flowers. Neither of these will stand wet winters, and they grow only in the South.
Blooming yucca then fertilizes the plant with pollen from another yucca. When the pronuba grubs hatch out, they find a goodly supply of seeds to eat, but leave plenty to produce more yuccas. Scientists call the yucca-pronuba relationship a perfect example of symbiosis, the mutual interdependence of two things in nature.
Our-Lord’s-candle (Y. Whipplei) has short basal leaves but sends up great creamy spikes, bearing many blooms. It will not stand frost or wet soil.
Northern gardeners who have never grown the hardy yuccas are missing plants that add great beauty and accent to gardens. One of the best yuccas for northern gardens is the Adam needle (Y. filamentosa), sometimes calm needle palm. It is a deep-rooted, tough-fiberish and some plant that has no trouble in New England winters. Its flower may rise 12 feet or higher. Y. flaccida is a similar species.
Other yuccas for the North are soapweed, and Y. data, both good as far north as southern Minnesota, good drainage and shelter against harsh wind are provided. Y. gloriosa is reportedly able to withstand city smog.