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Persian violet is grown and sold as a flowering pot plant with a working life measured in weeks, not years. A plant bought in bud will normally give you six to ten weeks of flower in a good room, and rather less than that in a warm one. It is not a houseplant that gets bigger and better each season, and treating it as one leads to disappointment and to a lot of unnecessary feeding and repotting. Everything below is aimed at getting the longest, densest flowering out of the plant you have.
The plant itself is a low dome eight to twelve inches (20 to 30 cm) across, covered in small five petalled flowers, each with a prominent cluster of yellow stamens in the middle. The flowers are lightly scented and open in succession rather than all at once, which is why the picking off of finished ones matters so much: the plant is always working on the next wave, and your job is to keep it doing that instead of setting seed.
Once flowering genuinely stops and the stems go woody and bare at the base, the plant is over. Most growers replace it. There is no dormancy to manage and no cutting back that reliably brings a second season indoors, so do not spend the winter nursing a bare plant in the hope of a repeat.
Light: bright, but never baked
Give it the brightest position you have that is out of direct midday sun. An east facing windowsill is close to ideal: several hours of gentle morning light, then bright shade for the rest of the day. A north facing window works in the brighter half of the year and is often too dim in winter. A south or west window is fine if a net curtain, a blind or another plant stands between the glass and the leaves during the strongest hours.
Too little light shows up first in the buds. Stems lengthen, the spacing between leaf pairs opens out, and buds form but stay small and green and drop without opening. The flowers that do open are paler and fewer. Move the plant closer to the glass and the next round of buds comes noticeably better, though the stretched growth stays stretched.
Too much direct sun shows up in the leaves. Exacum has thick glossy leaves that look tough but scorch readily, going pale and papery in patches on the side facing the glass, and the flowers bleach and finish within a day or two of opening. Direct sun through glass also heats the pot, which is the fastest way to lose a plant in summer. Turn the pot a quarter turn every few days so the dome grows evenly rather than leaning.
| Position | Verdict | What you will see |
|---|---|---|
| East window, cool room | Best | Compact dome, buds opening steadily for weeks |
| North window, bright half of year | Good | Slightly fewer flowers, good leaf color |
| South or west window behind a sheer curtain | Good | Strong flowering if the room stays cool |
| South window, unfiltered midday sun | Poor | Bleached flowers, papery leaf patches, hot pot |
| Table in the middle of a warm room | Poor | Stretched stems, buds that drop before opening |
| Above a radiator or beside a heat vent | Worst | Limp leaves within hours, flowering stops |
Temperature and air: cool rooms keep it flowering
The plant does best between about 60 and 70F (16 to 21C) with a drop of several degrees at night. It tolerates a little more warmth if the air is not dry, but a hot dry room is what finishes most Persian violets early. Above about 77F (25C) with dry air, the flowers last a day instead of several, buds abort at pinhead size, and the whole dome softens. Below about 50F (10C) growth stalls and the leaves can take cold damage, so it is not a plant for an unheated porch in winter.
Dry air is the specific problem, not warmth alone. Central heating, a fan heater, an open fire or a sunny sealed window all pull moisture out of the leaves faster than the roots replace it, and the plant wilts even though the compost is damp. If your plant is limp in the afternoon and firm again by morning, the room is too hot and dry, and adding water will only cause rot. Move it somewhere cooler instead.
Raise the humidity around the plant rather than in the whole room. Stand the pot on a saucer of gravel kept wet, with the pot base sitting on the stones and clear of the water line, or group it with other pot plants so they share a moister pocket of air. Do not mist the plant: water sitting among the crowded flowers and leaf joints leads straight to gray mold, and the marks it leaves on open flowers do not come out.
A Persian violet that wilts every afternoon and recovers overnight is telling you about air temperature, not thirst. Check the compost with a finger before reaching for the watering can, and move the plant before you water it.
Watering and feeding without rotting the base
Water when the surface of the compost has just dried and the pot feels lighter, then water thoroughly until it runs from the drainage holes, and tip away everything that collects underneath within a few minutes. The single most common way to kill this plant is to leave it standing in a saucer, a cachepot or a decorative sleeve holding water. The stems rot at soil level, the whole dome goes limp at once, and by the time you notice, nothing can be done.
Water at the edge of the pot rather than over the middle of the plant. The crown is crowded with short stems and buds, and water poured into the center sits there. Room temperature water is fine; very cold water straight from the tap can mark the leaves. In a cool room in winter this might be once a week, and in a bright warm room in summer it can be every other day, so judge by weight and by the compost, never by the calendar.
Feed lightly. A balanced liquid houseplant feed at half the label strength every two or three weeks while the plant is in flower is plenty. Heavy feeding produces soft leafy growth and fewer flowers, and it will not extend the plant's life. If you have just bought the plant, it will have been fed in production and needs nothing for the first two or three weeks.
- Take off the wrapping the day it arrives Plastic sleeves and foil pot covers hold water at the base and trap damp air among the leaves. Remove them, put the pot in a saucer you can empty, and check that the drainage holes are actually open.
- Check by weight, not by schedule Lift the pot when you have just watered it and again a few days later. The difference is obvious after a couple of goes, and weight tells you what a finger in the surface cannot when the compost is peat based.
- Water at the rim and drain it fully Pour steadily around the edge until water appears at the bottom, wait five minutes, then pour away whatever is in the saucer. Never top up a saucer as a way of watering.
- Deadhead at the same time Make the watering round the moment you also pick over the plant for spent flowers. Pairing the two jobs is the simplest way to make sure the deadheading actually happens daily.
What to write down
Because the plant is short lived, the record that helps you next time is about timing rather than about the individual plant. Note the date you brought it home and what state it was in, the date the first flower opened, and the date you decided it was finished. Two or three plants recorded that way tell you how long a Persian violet actually lasts in your house, which is far more useful than any general figure.
Also note where the plant stood and roughly how warm that room was. If one plant in a cool bedroom ran for ten weeks and one in a heated living room ran for five, you have learned the most important thing about growing this species in your particular home, and the next plant goes straight to the right windowsill.