Growing melastomes from seed is an inexpensive way to get many plants, and it gives access to species that are not sold as plants. It is also slow, and the seeds are tiny, so it is worth knowing what to expect.
What the seeds are like
Capsule-bearing melastomes, such as Tibouchina-type shrubs, produce very fine, dust-like seeds (seed dispersal in melastomes). Berry-bearing species produce slightly larger seeds embedded in pulp. Both are small, and many need light to germinate.
Getting seed
- Buy from reputable seed suppliers who identify species correctly.
- Collect from your own plants by letting capsules ripen and dry on the plant, then shaking the seeds onto paper.
- Do not collect seeds from wild plants without permission, and check regulations before importing seeds.
Important caveats
Seeds from named garden cultivars may not come true, and seeds from plants grown near other related plants can be hybrids. If you need an exact copy of a plant, use cuttings (propagating Tibouchina from cuttings).
What you need
- A shallow tray or small pots with drainage.
- Fine, sterile seed-starting mix, lightened with a little fine sphagnum or perlite. Slightly acidic is best.
- A clear dome or plastic bag to hold humidity.
- A warm, bright spot out of direct sun, or a grow light.
- Low-mineral water in a fine mister or for bottom watering.
Sowing step by step
- Fill the tray with damp mix and level the surface.
- Sprinkle the seeds thinly on top. Mixing them with a pinch of fine dry sand helps spread them evenly.
- Do not cover them. Light aids germination, and burying tiny seeds can prevent it.
- Lightly mist or water from below so you do not wash the seeds away.
- Cover with a clear lid to hold humidity, leaving a small gap for air.
- Keep warm, around 21 to 27 °C, with bright indirect light.
Germination
Germination can take anywhere from a couple of weeks to a couple of months, depending on the species and the freshness of the seed, and it is often uneven. Keep the surface moist throughout. Avoid letting it dry out, which kills newly germinated seedlings.
Caring for seedlings
- Remove the lid gradually once seedlings are established, to harden them off.
- Thin overcrowded seedlings.
- When they have two or three pairs of true leaves, prick them out into individual small pots using a spoon or tweezers, handling only by the leaves.
- Feed very lightly with diluted fertiliser once they are growing steadily.
Common problems
- Damping-off: seedlings collapse at soil level, caused by fungi in wet, stagnant conditions. Use sterile mix, ventilate and avoid overwatering.
- Algae or moss: a sign of constant wetness. Increase airflow.
- No germination: old seed, too cool, buried too deeply or dried out.
How long until flowers?
Fast-growing shrubs can bloom in a year or two. Slower species and trees take longer. Be patient.
A responsible note
Melastomes spread by tiny seeds can become weeds in suitable climates. If you live in a warm, humid region, avoid species known to be invasive and prevent seed escaping (why some melastomes are considered invasive weeds).
Takeaways
- Sow fine seed on the surface and do not cover.
- Keep it warm, humid and lit.
- Expect slow, uneven germination.
- Use cuttings when you need an exact copy of a plant.