43 · Plant Propagation & Overwintering
Ponds are cheap to stock once you can multiply your own plants. Dividing and storing keeps a pond full and free.
Dividing marginals
Every 2–3 years lift clumps in spring, split with a spade at the crown, and replant vigorous outer sections in fresh baskets. Discard the dead centre.
Cuttings & runners
- Water mint, creeping Jenny — root stem cuttings in a jar of water.
- Oxygenators — weigh down broken tops; they root readily.
- Iris — divide rhizomes after flowering.
Overwintering tropicals
Non-hardy lilies and some marginals must come indoors. Drop them into a frost-free tank or damp sand in a cool, bright space. Let tropicals go dormant rather than forcing growth under weak light.
Storing & replanting lilies
Lift tender lilies before the first hard freeze. Keep tubers damp and cool (not frozen). Repot into shallow baskets in spring once water warms, then lower gently back in.
Hardening
Acclimate stored plants gradually: a week in decreasing shade before full sun prevents shock and melting leaves.
Propagation methods for aquatic plants
| Method | Best for | When |
|---|---|---|
| Division | Iris, marsh marigold, water mint | Early spring or autumn |
| Runners | Water lilies, duckweed | Spring/summer |
| Stem cuttings | Oxygenators (hornwort, elodea) | Any time in growing season |
| Seed | Annuals, wildflower mixes | Spring (sow on moist compost, flood gradually) |