by Bruce Brethauer
Yucca elephantipes has been a mainstay of of the houseplant industry for many years, and with good reason: it is a forgiving plant which is generally very easy to grow, pest free, and, where it is happy, will make good growth every year. It is easy to propagate, and is more shade tolerant than any other arborescent yucca, making it better suited to the lower light of interior spaces. Good sized plants are relatively inexpensive, and are readily available from practically any "big box" nursery.
The species is native to the Veracruz coast of Mexico and south to Guatemala; I believe that it occurs semi tropical regions which may experience periodic or seasonally dry periods. It is also reputed to be adapted to somewhat shaded conditions. Mature plants will grow to about 30 feet in height, eventually producing large woody trunks with upwards of 50 branches growing from it. The trunks can eventually become quite massive, with a shape reminiscent of a Ponytail Palm: some growers even suggest that the size of the caudex on a mature specimen may exceed that of a Ponytail Palm. In mature plants, leaves may grow to 4 feet in length, and to 2 or 3 inches wide, but are considerably smaller in the less mature plants offered in nurseries. Initially, the leaves grow upright but may become somewhat more reflexed in older and larger leaves. The leaves of plants in cultivation are typically a grey-green to nearly blue green coloration due to a very light waxy coating on the leaf surface, but plants in habitat are said to have more glossy green foliage. This species is sometimes called the "Soft Spined Yucca", because the leaf tips do not end in an extended, rigid, and sharp tip, but this name is a bit misleading: the leaves do end in a point, and since the younger leaves are held rigidly upright, the leaf tips are capable of causing injury - In my days at Bell Nursery, I know of at least 3 occasions when workers have been poked by this plant - 2 occasions resulting in a minor eye injury, and a third causing a nosebleed - it is best to keep this plant a least a few feet from high traffic areas.
A good many of the plants which I have seen in cultivation are not completely true to the species, and I suspect that the greater portion of the plants being offered as Y. elephantipes in the trade may in fact be a hybrid plant - perhaps a hybrid of this species and Yucca gloriosa. The true species is essentially a tropical plant, and while it can survive considerable chill, it apparently will not survive more than a few degrees of frost. In warmer Mediterranean climates, it can be grown outdoors, where it has earned a reputation for being a tough survivor, tolerating drought and high rainfall, high temperatures and chill; but in low desert regions, it will need additional watering, and somewhat shaded conditions - otherwise its leaves tend to become scorched. Here in the Midwest, this plant makes an excellent summer patio plant - provided that it is properly acclimatized to the increased light levels of direct sun - otherwise its leaves will become scorched.
My plant originated from a cutting taken from a plant in Geno Centofanti's collection ( I think it was from the plant which he nicknamed "Sis"). Unlike many of the plants which I have seen offered at the "Big Box" nurseries, his was already acquiring a hefty caudex at a relatively young age, and I was hopeful to produce a multi-trunked specimen with similar properties. My cutting quickly put down roots, and during the course of this summer, produced about a dozen offsets (several of which I have already given away). It is still too soon to report on a caudex on this plant, but I remain hopeful. I grew my plant outdoors this summer to encourage rapid and strong growth, and was very much pleased with the results.
When plants are returned to interior spaces at the end of the season, the lower leaves may have a tendency to turn yellow and may eventually produce a thatched layer of dead and browned lower leaves below the green leaves on top. This thatch, or any yellowing or browning leaves may be removed by pulling downward on the individual leaves, but any yellowing and browning of leaves at this time should not be cause of concern - all yuccas will eventually shed their lower leaves as the plant grows, and will frequently shed leaves in response to changes in the seasons, drought, and other factors. If this yellowing should extend to the topmost portions of the plant, you probably have issues with watering - usually this is evidence of over-watering, but it may be evidence of extreme under-watering.
During their growing season (Spring through Fall), these plants can be watered frequently - it may be appropriate to keep patio plants evenly moist (but trending towards the dry side) most of the time. Plants should also be fertilized every few weeks through the growing season - I use a dilute solution of Miracle Gro Bloom Booster, but any similar fertilizer would be fine. From late fall through winter, the soil should be kept drier - always allow the soil to become dry - and remain dry for about a week, before watering this plant at this time. Cooler temperatures are also best at this time. Even though this species is tolerant of shaded conditions - whenever it is grown indoors, it is best to provide as much light as possible for best growth - more is always better. This plant is highly resistant to insect infestations: if you notice any issues with pests, there may also be other issues which need to be addressed - plants may need drier, brighter conditions - or if spider mites are found, this plant may benefit from moister and somewhat cooler conditions (spider mites are usually a problem during hot and dry seasons).
Yucca elephantipes is a great patio and house plant, it has a great architectural form, and its growth habit is mostly upright, rather than spreading - so it does not tend to have a huge footprint on the patio or in interior spaces. It is highly resistant to drought, and tends to be very forgiving of missed waterings and other issues. It is widely available through practically any "Big Box" nursery - and is usually available in a number of sizes and price points. Several online sources indicate that there are several variegated cultivars of this plant, providing additional color variations, but to date, I have not seen these cultivars in any garden departments in Ohio (how about it, Home Depot, Loews, Menards, and Andersons)? If you are one of the lucky few, you will eventually get a plant which produces a significant woody caudex. All in all, this is a plant which is worth a second look; even from those of us who profess to have more discriminating tastes in our houseplants.