Yucca
Also called Spineless yucca, Giant yucca, Stick yucca, Yucca elephantipes.
| Light | full sun |
|---|---|
| Water | Every 14 days in the growing season, every 30 in winter |
| Pets | Cats toxic, dogs toxic |
Source: ASPCA Animal Poison Control, toxic and non-toxic plants list.
Toxic to cats and dogs if chewed. Listed as toxic to cats, dogs and horses. The saponins cause vomiting in cats and dogs. The leaf tips are also sharp enough to hurt an animal or a child at eye height. Keep it where an animal that eats houseplants cannot reach it, and speak to a vet if one does. In South Africa telephone the Poison Information Helpline on 0861 555 777; in the US, the ASPCA Animal Poison Control Center on (888) 426-4435.
The spineless yucca comes from Central America, from Mexico down to Guatemala, where it grows into a real tree with a swollen woody base and a head of strap shaped leaves. It is sold as one or more thick canes with a tuft on top, which is exactly what it is: a length of trunk that has been cut, rooted and potted, because yucca canes root so readily that whole plantations are grown for the purpose. That habit is the key to the plant. It is tough, it is dry loving, and when it gets too big for the room you simply cut it and start it again.
Light
The brightest position you have, with several hours of direct sun. A south facing window in the northern hemisphere or a north facing one in the southern, or an open spot outdoors in summer once the nights are mild.
In poor light the leaves grow longer, softer and floppier, and the head loses its stiff fountain shape. That growth does not firm up again, so more light now and a cut back in spring are the answer. Introduce a plant that has wintered indoors to full sun over about two weeks, or the leaves scorch.
Water
Soak the compost thoroughly, then let it dry most of the way through before watering again, which is roughly every two weeks in summer and once a month in winter. Judge it by weight rather than by the surface, because a gritty mix looks dry on top long before it is.
Everything that kills a yucca indoors comes back to water. The cane is a store, the roots are used to draining ground, and compost held damp around the base for weeks turns the bottom of the cane soft and brown. By the time you notice, the base is gone, though the top can nearly always be rescued as a cutting.
Feeding and repotting
Two or three half strength feeds across spring and summer, and nothing from autumn. Repot every third year at most, in spring, into a pot barely wider than the root ball. Weight matters: a two metre yucca in a light plastic pot spends its life being picked up off the floor, and a heavy pot solves it.
Pruning and starting again
This is the great virtue of the plant. When it reaches the ceiling, cut the cane straight across in spring with a saw or heavy secateurs, at the height you want the new head to start. The stump looks brutal for six weeks and then breaks two or three new shoots from just below the cut.
Nothing needs to be wasted. The leafy top roots as a cutting: let the cut dry for a few days, then push it into gritty compost and water sparingly. The bare length of cane between them can be cut into sections of twenty centimetres or so and rooted the same way, as long as you keep them the right way up, so mark the top of each piece before you cut.
The other yuccas
The one sold as a houseplant is nearly always this species, which has soft leaf tips you can press without hurting yourself, and it is still often labelled Yucca elephantipes, an older name carried here as an alias. Its garden relatives are a different proposition: Yucca gloriosa, Yucca filamentosa and the rest are hardy in temperate gardens and have leaf tips sharp enough to draw blood. If a plant is being sold for a border rather than a living room, check which one it is before deciding where to put it.
Ailments
A steady loss of the lowest leaves is the plant building a trunk, not a fault. Several yellow leaves at once with damp compost is overwatering. A soft base is cane rot and means the top has to be saved and the base thrown away. Long soft floppy leaves mean too little light. Brown tips are water quality or dry air. The ledger below has the rest.
Ailments observed
| Yellow leaves at the bottom of the plant | Old leaves being shed as the cane grows, or overwatering. A steady loss of the lowest leaves is normal and is how the trunk forms. Several at once with damp compost is too much water. |
|---|---|
| A soft or mushy base to the stem | Cane rot from compost that stays wet, most often over winter. Cut the cane back above the damage into firm tissue, let the cut dry, and re-root the healthy top. The rotted base cannot be saved. |
| Long bare stems and pale new leaves | Not enough light, giving long soft leaves and a stretched cane. Move it to the sunniest position you have, and cut the cane back in spring to force a tighter head of new growth. |
| Brown tips on otherwise healthy leaves | Dry air, fluoridated tap water, or feed salts. Use rainwater, flush the pot with plain water every few months, and trim the brown to a point. |
| Spots on the leaves | Fungal leaf spot, which follows water left standing on the leaves in a cool room. Water the compost rather than the plant, improve the air movement around it, and remove the worst leaves. |
Questions from the margin
How often should I water an indoor yucca?
About every two weeks in the growing season and once a month in winter, once the compost has dried most of the way through. The cane is a water store and the plant is far easier to drown than to dry out.
Why are my yucca's lower leaves going brown?
If it is the oldest ring of leaves, one at a time, that is normal and is how the bare trunk forms. If several go at once and the compost is damp, the roots are drowning.
My yucca is too tall. Can I cut it?
Yes. Cut the cane straight across in spring at the height you want, with a saw or heavy secateurs. New shoots break from below the cut within a couple of months, and both the leafy top and the piece of bare cane will root as cuttings.
Is a yucca dangerous to pets?
It is listed as toxic to cats and dogs, with saponins causing vomiting. The leaf tips are also genuinely sharp, which is worth thinking about at the height of a dog's face or a child's eyes.
Filed underPlants that forgive a beginner, Statement plants
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