Goldfish Plant
Columnea Care Guide
Columnea is a genus of trailing and shrubby gesneriads from the cloud forests of Central and South America, grown indoors for their tubular orange, red and yellow flowers that look like leaping fish. The single most important thing to get right is consistent moisture and humidity. They flower well in a UK home, but only when the roots stay evenly damp and the air is not bone dry.
This guide covers light, watering, soil, repotting, propagation, the species we recommend most, and the common problems that come up in our nursery.
Light Requirements
Bright, filtered light is best for Columnea. Think 1 to 2 metres back from a south or west window, or directly in an east window. Columnea evolved as an epiphyte clinging to the canopy, so it wants brightness without harsh midday sun.
Too much can cause bleached pale leaves and crispy edges. Move it back from the glass.
However, too little light can result in long, leggy stems with widely spaced leaves and no flowers. In a north-facing room or a dim corner, supplement with a grow light.
For winter flowering on cultivars like Columnea 'Krakatau', a top-up of 6 to 8 hours under a horticultural light will keep buds setting through the dim UK months.
How Often to Water Columnea
Water when the top 2 cm of compost feels just dry, never let the rootball dry out completely. In summer that is usually every 4 to 6 days; in winter every 8 to 12 days.
Columnea is less drought tolerant than its cousin Aeschynanthus. The fine, hair-like roots dry out quickly and the plant drops flower buds at the first sign of stress.
Yellowing lower leaves, mushy stem bases, and a sudden flush of dropped leaves are all common signs of overwatering. The compost will smell sour. Tip the plant out, cut away any black roots, and repot into fresh, airy mix.
Dull, papery leaves; flower buds shrivelling before they open; whole sections of stem going crispy can be a sign of underwatering. Soak the rootball in tepid water for 10 minutes, then drain.
Use rainwater or filtered water if your tap is hard. London tap water in particular leaves a chalky residue that Columnea dislikes.
What Humidity is best for Columnea?
This is where most UK growers come unstuck. Columnea needs 60 percent humidity or higher to flower well and keep its leaves looking sharp. Living-room humidity in winter often drops 35% or lower with the heating on.
Practical fixes, in order of how much they actually help:
- Group your humidity-loving plants together so they share transpired moisture.
- Stand the pot on a pebble tray with water below the pot base.
- Move it to a brighter bathroom or kitchen.
- Run a small humidifier nearby, ideally with a hygrometer so you are not guessing.
We do not recommend misting. It does not raise ambient humidity for any meaningful length of time, and the wet leaves invite Botrytis and bacterial spotting on gesneriads, which is what we see most in returns.
Repotting
Repot every 18 to 24 months in spring. Columnea flowers better when slightly potbound, so do not jump up more than one pot size. Most of our nursery stock sits happily in 12 to 14 cm pots for years.
- Water the day before so the rootball slides out cleanly.
- Tease away the top centimetre of old compost and inspect the roots. Trim any black or hollow ones.
- Move into a pot 2 cm wider, with fresh aroid mix.
- Water sparingly for the first two weeks while the roots settle.
If you grow it as a hanging basket, stick to terracotta or breathable plastic. Heavy ceramic that holds water is a quick route to root rot.
When it comes to potting soil, our Jungle Mix works well for Columnea straight out of the bag. Our top tip would be to avoid coco-only mixes. They hold too much water and pack down within a few months.
Do I need to feed my Columnea?
Yes. Feed Columnea every two weeks from March to October at half the recommended rate, using a balanced houseplant feed. We use Liquid Gold Leaf on our gesneriads in the nursery; it is gentle enough for these fine roots and triggers flowering reliably.
In autumn, switch to a feed slightly higher in potassium for six weeks to push winter flowering, then ease off entirely from December until light levels start to climb again in February.
Common Problems when growing Columnea
Bud drop. The number one issue and it is commonly caused by sudden temperature shifts, draughts, or letting the compost dry out while in bud. Once buds drop, the plant will not retry that flush. Keep conditions steady.
Yellow lower leaves. This is usually overwatering, occasionally underfeeding. Check the rootball before you reach for the watering can.
Crispy leaf edges. Can be a sign of low humidity, or hard water salts building up. Flush the pot through with rainwater every few months.
Powdery mildew. Appears as white dust on the leaves in still, damp air. Improve airflow with a small fan and remove affected leaves. Our guide to managing powdery mildew on houseplants covers the full treatment.
Pests. Aphids and thrips both target the soft new growth. We see thrips most in summer when windows are open. Inspect the underside of new leaves weekly.
Columnea is one of the more rewarding flowering houseplants we grow. Get the watering and humidity right and it will flower for months in a UK home, with very little fuss in between.
If you are unsure which species suits your conditions, drop us a message; we are happy to help match a plant to your space.