Tips on growing
Poor Knights Lily
Climate -- Xeronema comes from a mild climate and is happiest between 40 and 75° F (5-23°C), with cool nights. I know someone in Puerto Rico whose plant did well at 85-90° F (31°C) and warm nights, but i don't know if Xeronema will always be happy in those conditions.
The plant can probably take a few hours at 28-30° F (-2°C) and maybe lower, but i strongly recommend protecting the plant from all frost.
Indoors, if the humidity gets below 40%, consider using a room humidifier.
Soil -- It seems to do best in a fast-draining, rocky medium, with regular, light watering. A typical soil mix is 1 part potting soil, 1 part pumice rock (or perlite, medium gravel, etc), and 1 part coarse horticultural sand. If your potting soil doesn't contain nutrients (check the package) mix in some slow-release fertilizer, preferably organic or pelleted (more on this in the "fertilizer" section below).
Use a pot about 2-3 times bigger than the one it's growing in. The pot needs drainage holes. Avoid a dark colored pot, which can heat up the roots.
When transplanting, avoid letting the soil ball break apart, which disturbs the roots. Watering the soil before repotting can help keep it together. After transplanting, avoid direct sunlight for a few weeks, and protect from temperature extremes.
Watering - On the islands, they are bathed by light rainfall every couple of days. Some say that Xeronema is drought-tolerant, however my experience is that they can wilt or burn if the soil dries out, and this can stress the plant. So i recommend giving regular, light watering. It's hard to over-water the plant if grown in fast-draining soil and kept in a sunny spot. But avoid the combination of shade and soggy soil, as this can lead to rot. If you tend to over-water your plants, add extra pumice/perlite to your soil mix.
Sunlight -- They grow well with mostly sunny conditions, with some filtered sun or shade during warm afternoons. Along the cool Pacific coast they can handle full sun, but will require more frequent watering and fertilizing.
Fertilizer - On the islands, the plants are fed with seabird droppings, which are high in nitrogen and phosphorous. You can simulate this with bird guano, which is sold at some garden shops, and online. Or you may use any slow-release fertilizer that is rich in nitrogen and phosphorous - preferably an organic or pelleted fertilizer.
Xeronema grows slowly so it doesn't need much fertilizer. Moderate feedings about every 2 months should be enough, especially for a younger plant.
It's normal for an older leaf to occasionally turn yellow and die, but if it seems excessive, the soil may be too dry down in the root zone. Or the plant may need more fertilizer (nitrogen).
Some websites recommend giving the plant seawater a couple of times a year, but i haven't felt comfortable trying this. On the islands, they probably are sprayed with sea mist, although personally i would dilute any seawater you give your plant. I do recommend mixing some kelp powder into your soil, which you can buy at garden shops and online. Or you can water occasionally with a seaweed extract like Maxi-Crop, which has a lot of goodness from the sea but without the salt.
Small pot? -- Some websites that the plant needs its roots cramped in a small pot in order to flower, however i have seen it flower very nicely in open ground as well as oversized containers. They do not seem to flower any sooner when root-bound, in my experience. I recommend giving your plant ample root space for at least the first few years, so it can grow quickly. A large pot will help keep the roots cooler too. When the plant nears flowering-size, avoid repotting it, as this could delay flowering. If you must repot, avoid disturbing the root system.
Propagating - If your plant has an offshoot with its own root system, you may separate it. Keep in mind that dividing a plant that is near flowering-size may delay flowering by a year or more.
If you have any questions, feel free to contact me.
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