Light is the second great variable in melastome care, after water. The family includes plants adapted to deep forest shade and plants that thrive in full tropical sun, so one rule does not fit all.
Why light matters
Light drives growth and, in flowering species, bud formation. Too little leads to stretched, pale growth and few flowers. Too much scorches leaves, particularly on species adapted to shade.
Three broad groups
1. Shade lovers. Small forest-floor herbs such as Bertolonia and Sonerila. They need low to moderate light, with no direct sun. Their patterned leaves can bleach or burn quickly in strong light.
2. Bright-indirect plants. Epiphytes and understory shrubs such as Medinilla magnifica. They want bright, filtered light, like the dappled light under a forest canopy or near a window with a sheer curtain.
3. Sun lovers. Garden shrubs such as the princess flower (Tibouchina in the garden) and open-habitat plants like Osbeckia. They flower best in full sun to light shade, with some afternoon shade in very hot climates.
Measuring light
As a rough guide, bright indirect light indoors often measures in the thousands of lux, whereas direct midday sun can exceed fifty thousand. Many phone apps and inexpensive light meters give an approximate reading. Use readings as a comparison between locations rather than as exact targets.
Reading the plant
- Too little light: long gaps between leaves, small pale leaves, leaning towards the window, no flowers.
- Too much light: bleached or yellow patches, brown crispy spots, curled leaves, wilting at midday despite moist soil.
Windows and direction
In the Northern Hemisphere, a south-facing window is brightest, east is gentle morning sun, west gives hot afternoon sun, and north is dim. In the Southern Hemisphere, these are reversed, so north-facing windows are the brightest. Sheer curtains can soften harsh light.
Using grow lights
Full-spectrum LED grow lights work well for melastomes indoors.
- Place the light at the manufacturer's recommended distance, usually further for sensitive plants.
- Run it for about twelve to fourteen hours a day on a timer.
- Watch for bleaching and adjust distance if necessary.
- Use stronger light for flowering shrubs and gentler light for forest-floor herbs.
Acclimating plants
A plant that has lived in low light will burn if suddenly moved into sun. Move it gradually over one to two weeks. The same applies after buying a plant from a shaded nursery bench (choosing a healthy melastome at the nursery).
Seasonal changes
Light intensity and day length change through the year. Plants may need to be moved closer to windows in winter or shaded in summer.
Takeaways
- Match light to the plant's origin: shade, filtered or sun.
- Watch the plant for signs of too little or too much light.
- Acclimate plants gradually.
- Grow lights make indoor cultivation feasible.