Propagating Aquatic Plants: Vegetative Methods for Water Gardens

Water Plant Propagation

Raising Aquatic Plants by Vegetative Methods

Normal vegetative methods—increasing aquatic plants by division, cuttings, or eyes—are easily executed even with basic facilities. A good light windowsill is often all that’s needed for quality plants.

Division

Almost all aquatic and bog garden plants can be divided in spring. Divide the crown into two or more pieces, pot or plant individually. For creeping rootstocks (reedmaces, rushes), remove a length with a terminal shoot. Clump-formers (iris, water plantain, marsh marigold) separate by hand or trowel like herbaceous plants.

Bog garden plants: established clumps pried apart in dormant season; outer, vigorous young pieces replanted.

Root Cuttings

Many bog garden plants increase readily from root cuttings—done during dormant season. Lift parent, remove suitable root pieces, return parent. Best roots: pencil-thick, not too thin. Cut 2.5 cm (1 in) pieces, lay horizontally in trays of good seed compost, cover lightly, water, place in cold frame. Within weeks they sprout; lift carefully, pot individually in small pots for growing on, plant out next autumn or spring.

Drumstick and candelabra primulas benefit most; many vigorous perennials with fleshy thong-like roots also respond.

Storage Organs

Some aquatics produce turions or winter storage buds. Arrowhead or flowering rush produce food storage organs, but they’re produced freely and can be separated to develop as new plants. Floating and submerged aquatics use turions for natural dispersal—gardener need not interfere.

Stem Cuttings

While most marginal/bog plants divide well, some propagate better from stem cuttings each spring. Water mint and brooklime, though divisible, make better plants from short stem cuttings.

Take non-flowering shoots ~5 cm (2 in) long in late spring when actively growing. Insert into tray/pot of sandy loam or friable stone-free muddy soil, partially or fully submerged. Rooting in 10–14 days. Lift, pot, grow on individually.

Submerged aquatics mostly increased by stem cuttings during growing season. Gather into bunches, fasten with thin lead strip, push into permanent position in compost; lead remains around bunch.

Waterlilies from Eyes

All hardy waterlilies except Nymphaea ‘Pygmaea Alba’ (seed or occasional division) are best propagated from eyes—tiny growing points along/around rootstocks of mature plants. Usually like smaller main growing points with juvenile foliage; in N. tuberosa and cultivars, they’re brittle rounded nodules.

Lift adult hardy waterlilies in spring/early summer, remove required eyes with sharp knife. Dust wounds of rootstock and eye with powdered charcoal to reduce fungal risk. Pot eyes in small pots/modular trays with soil-based compost, stand in shallow container filled to pot rims. Tiny eyes benefit from cold frame/greenhouse protection early on. Move to progressively bigger pots and deeper water until ready for pool planting.

Waterlilies from Other Methods

Some tropical waterlilies increased from seed, but named cultivars best propagated by separating young plants in spring. Pot tubers at ~21 °C (70 °F) in sun. Within weeks, first true floating leaves appear. Locate stem-like growth connecting young plant to tuber; pinch off next to tuber, removing young plant with roots intact, leaving tuber to regrow. Can do this two or three times per tuber before final growth for the season.

Several tropical waterlilies are viviparous, producing young plantlets on leaves. Regularly remove and pot up as fresh plants.

Propagation by Division – Summary

1. Divide established plants carefully; use youngest, most vigorous portions. Discard old material.
2. Trim foliage hard (it will likely die anyway). Cut back roots; remove suspect decaying rootstock.
3. Replant in clean aquatic compost in appropriate basket. Water well, driving air out before placing in water.

Propagation by Stem Cuttings – Summary

1. Remove healthy non-flowering stems from actively growing plants (spring/summer).
2. Clean foliage, gather in small bunches up to 5 cm (2 in). Fasten neatly at base with thin lead strip.
3. Plant bunches in aquatic baskets with compost. Bury lead weight beneath compost or it will rot stems and tops float away.