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Propagating Water plants

See the Starting From sections for general information on propagation techniques, including those for water plants. Specifics on growing and reproducing a species are given only if these differ from the usual.

Propagation of water plants, especially by seed or cuttings, differs from that of their land-bound cousins. Seed should be sown immediately when fresh, since drying out quickly kills the seed of most species. Re-gardless of how deep a plant grows, seed is sown just covered on regu-lar, sterile, seed-starting medium; seed trays are then set in some other container so that the water level is just below the soil level - old aquaria work well.

When germination occurs, raise the water level for deep water aquatics, so these are covered completely, and continue to bring it up as the plant grows; other plants may be kept very wet. When true leaves develop, seedlings may be pricked out and grown on in larger pots; repot as ne-cessary during growth. Ample light should be provided throughout.

Similarly, root and stem cuttings are planted into heavy soil or muddy clay; for deep-water plants, root cuttings should be just covered with water. As new plants grow, gradually submerge deep-water plants, so that the shoots stay just at or below the water surface. Stem cuttings benefit from use of rooting hormone; water should just cover the soil surface, but not the cuttings themselves. Once rooted, cuttings may be lowered to their final depth. Marginal plants should be kept very wet, but not submerged.

For aquarium plants, in general, provide water of 3 to 12 degrees of hard-ness, a water temperature of 70-85F/21-29C, and a depth of up to 20" are ideal, as is a pH in the range of 6.5-7.5. Where cultural conditions differ significantly from these values, this is indicated. Finally, aquarium lighting is discussed in detail, elsewhere.

Acorus calamus

sweet flag, sweet-scented rush

This hardy perennial requires very moist soil or up to 8" below water level. Sun or part shade. Divide in spring, leaving at least 2" of rhizome per crown. Also known as A. americanus. Zone 3-9

Acorus gramineus

grass-leaved sweet flag

Marginal grown in up to 6" of water. Divide in spring or summer. Grown indoors, will tolerate somewhat darker corner; protect from full sun. Zone 6-10

Alternanthea reineckii

copperleaf

Divide in spring; grow from stem tip cuttings also at this time. Medium light. Suitable for aquarium use

Aponogeton crispus

As an aquarium plant, desires medium light; goes through dormant phase. Divide during flowering in spring, may also be sown from seed while fresh

Azolla caroliniana

fairy moss, mosquito plant

Reproduces readily: scoop a handful and move to any desired new lo-cation. Full sun to part shade. Overwinter indoors in zone 6 and colder

Cabomba caroliniana

fanwort, Washington grass

Submerged aquatic suitable for the aquarium, grown in very bright light, up to 20" deep. Outside, prefers some shade. Grow from softwood stem cuttings in spring or summer. Avoid hard or alkaline water. Zones 9-10

Calla palustris

water arum, bog arum

Divide this marginal in late spring or early summer; bog plant native to acidic soils, does well in mud or up to 8" of water. Also grows readily from seed if sown when fresh. Sunny spot. Zone 3-8

Callitriche species

starwort

Submerged aquatics propagated easily from stem cuttings taken in summer; these are bunched and sunk to the bottom of the pond as for Elodea

Caltha leptosepala

Sow in early spring or when ripe in fall, very shallowly onto moist, peaty compost, 55-65F/13-18C; germination is erratic. Marginal, grow in up to 6" of water, sunny location. May also divide after flowering. Zone 5-9

Caltha palustris

 marsh marigold

Seed germinates at cooler temperatures, sown just covered ideally when fresh in fall; germination is irregular. Propagate also by dividing rootstock early in growing season, after flowering. Sun to shade, moist well-draining soil essential, tolerates clay soil well. Zone 4-9

Ceratophyllum demersum

hornwort, coontail

Aquatic plant, used in ponds and water gardens for oxygenation. Can simply be dropped into water; needs no planting; readily reproduces it-self. May also reproduce by stem cuttings in spring. Will tolerate some moving water. Medium to good light. Zone 6-10

Can also be used as aquarium plant; provide medium light or better

Colocasia esculenta

green taro

Used in water gardens in protected locations; plant at water level, or a few inches below. May be grown indoors, keep very moist. Divide tu-bers in spring. Sun to part shade. Zone 9-10

Cryptocoryne species

Good aquarium plants that tolerate good to poor aquarium lighting. Various species suitable for water 6" deep or less, some, like C. balan-sae, ideal for deeper tanks with flowing water. Most species do well outside the aquarium, in wet soil. Divide in spring or summer; should be planted directly into the soil or mud under the water's surface, or may gradually be submerged

Cyperus alternifolius

umbrella palm

Start from seed, moist medium, 70-75F/21-24C. Plant in very moist soil, with roots ideally a few inches above water level. May be kept as houseplant, overwinter indoors in cool climates, good indirect light. Di-vide in spring. May also propagate from leaf bracts, cut off the tips of stems, and placed upside down onto warm moist medium. Alterna-tively, bend the leaf bracts onto moist soil, and pin down: a new plant will eventually begin to grow. Zone 9-10

Also known as Cyperus involucratus

Cyperus papyrus

 papyrus

Seed is sown barely covered, as for C. alternifolius; cultural conditions also are virtually identical, though mature specimens are easily grown with up to 8-12" of water overhead

Drosera species

sundew

Seed, if available, may be surface sown onto evenly moist, peaty soil early in spring, 55-65F/13-18C; light is needed to germinate. Full sun, acidic peaty soil and constantly wet soil essential. May also be divided early spring. Hardiness of individual species varies markedly - some are strictly tropical, and others, i.e. D. rotundifolia, common or round-leaved sundew, grow throughout temperate zones

Many species are endangered, so buy specimens only from reputable dealers. Do NOT harvest specimens from the wild

Echinodorus parviflorus

black Amazon, Amazon sword

Good for the medium-light aquarium; does well in smaller tanks, with water to 12" deep. Propagate by division: clump-forming, and spreads on runners

Eichhornea crassipes

water hyacinth

Note that this floating aquatic is an invasive weed in warmer climates, and is restricted in some areas; must be overwintered inside in north-ern areas. Prolific by means of stolens: cut new plants free from the parent. Good light. Zone 8-10

Eichhornea azurea, the peacock hyacinth or creeping water hyacinth, another floating aquatic, requires large amount of space, and is other-wise grown and propagated in the same manner

Eleocharis acicularis

 hair grass

Propagate this submerged aquatic by division throughout the growing season; spreads readily over the bottom of pond or pool, and is also excellent in tub gardens. Will not grow from cuttings. Good soil. Zone 6-10

Elodea canadensis

Canadian pondweed

Submerged aquatic grown from bunched cuttings: tie these together with a lead strip around the base of the cuttings, and drop into water at least several inches deep, with good soil at the bottom, one bunch per 2 sq ft of surface area. Sun to part shade, still or gently moving water. Quite hardy

Euryale ferox

gorgon

Sow seed when ripe, or in spring. Deep-water annual with floating fo-liage. Full sun and consistently warm water required, as is fertile soil. Zone 10

Hottonia palustris 

water violet

Divide this submerged aquatic in late spring, early summer, or grow from stem cuttings also in summer. Does well with full sun, 12-18" of clear water overhead. Tolerant of some running water. Zone 5-9

Houttuynia cordata

Seed sown in spring in a protected location; does well in partial shade. Marginal, tolerates a few inches of water overhead. Perennial, good groundcover, spreads rapidly and can become invasive. New plants on runners may be divided off in spring. Zone 5-9

Hydrocharis morsus-ranae 

 frogbit

This floating aquatic overwinters by dropping buds, known as turions, to the bottom of the pond in fall, from which new plants develop in spring; these buds may be relocated, and overwintered indoors if de-sired. New plantlets also develop on runners and may be removed and resited in spring. Sunny spot, still waters. Zone 6-10

Hygrophila corymbosa

Submerged aquatic suitable for tropical aquarium, grown from stem cuttings spring or summer. Medium light; water to 24" deep. Zone 10

Hypericum elodes

marsh hypericum

Divide in spring, or root stem cuttings in summer. Shallow water or wet soil; good marginal. Good light. Zone 5-9

Iris species

Louisiana iris

See also Plants of Home and Garden. While the basic needs of many irises are the same, water irises do have particular needs. The name Louisiana iris applies to five North American species, including I. brevi-caulis and I. fulva. Propagation best done by division, as plants may not grow true from seed. Water up to 6" in depth is tolerated.

Iris pseudoacorus

 yellow water iris

Loves boggy conditions, just sunk up to 12" below water level in ponds, or grow in very moist soil. Vigorous, self-seeds freely; sow fresh seed in fall. Divide in summer after flowering. Full sun

Iris versicolor 

 blue water iris

Set roots just below water level, or grow in very moist soil; full sun to part shade. Divide after flowering or sow seed in spring or fall. Hardy to zone 4

Lemna trisulca 

ivy-leaved duckweed

Floating aquatic, divides naturally. Simply scoop and move to desired new area. Other species propagated in the same manner. Zone 5-9

Lysichiton camtschatcensis

skunk cabbage

Good marginal or bog plant started from seed sown when ripe into a protected, consistently moist location, or grown under several inches of still or even moving water. May be gently divided after flowering or in fall. Zone 7-9

Marsilea species

water clover

Divide these aquatics in spring; offsets may be removed if these are produced. May be grown with up to 12" of water overhead, or grow in constantly wet soil. Some are suitable for the aquarium

Menyanthes trifoliata 

bog bean

Propagate by dividing the creeping, submerged stem into sections, each with roots attached, in mid to late spring; replant immediately. Sun. Bog plant tolerant of up to 12" of water overhead. Zone 5-9

Microsorium pteropus 

Java fern, swordfern

Divide in spring, or grow from spores also sown at this time, onto a very moist soil surface, gradually submerging plants as they mature. Slow-growing aquarium plant ideal for poor light; needs to be tied to some form of anchor at the base of the aquarium, rather than planting in soil. Avoid hard water; tolerant of acidic conditions

Myosotis scorpioides 

water forget-me-not

Self-sows freely, seed may be sown onto soil surface in fall; dark may be required to germinate. Wet but fertile soil; established plants may be set slightly below water level. Divide in spring. Sun to some shade. Zone 4-10

Myriophyllum aquaticum

parrot's feather, water feathe

Propagate by stem cuttings, spring or summer; wrap bases of cuttings with lead and allow to sink down into soil or mud below water surface. Still to slowly moving water, part or full sun, no deeper than 3'. Colder areas take cuttings in late summer, overwinter in mud, temperatures cool but above 32F/0C. Divide in spring. Zone 7-10

Myriophyllum verticillatum

myriad leaf, whorled milfoil

Grow from bunched stem cuttings as M. aquaticum, above, taken be-fore flowering, or divide in spring; return to water immediately. Full sun. Partially submerged aquatic, hardy to zone 4-10

Nelumbo species

lotus

Plant tubers horizontally, with growing tips above soil; taking care not to injure these. Tips should also not be obstructed during growth, or the tuber may die. Cover with several inches of rich, heavy soil; in cool cli-mates, set out when the weather warms. Full sun, warm temperatures for good growth. Divide rootstock in spring, carefully. Some varieties hardy to zone 5; most to zone 10

Remove tuber from shallow ponds or container gardens before water freezes. Remove roots and leaves, and overwinter in consistently wet peat moss, at temperatures above 32F/0C and up to 55F/12C

Nuphar lutea

 yellow pondlily

Vigorous aquatic, requires large still ponds or lakes to grow comfort-ably, ideally several feet of water overhead. Tolerates partial shade. Divide rootstock early spring, or sow seed immediately upon ripening, just below water surface. Zone 4-10

Nymphaea species, cultivars

water lily

Requires good light, very rich soil, typically undisturbed and shallow water, though with good light and clear water some plants will grow up to 15' deep. The amount of room required varies per species and cul-tivar; some grow comfortably in half-barrels, 4-6" below water surface. Set rhizomes just below soil surface; leave crown bare. Divide the root-stock in spring, each section with one or two good eyes; start these close to the water surface, and lower to the final depth every few weeks

Can also be propagated from seed, though may not come true to type, and takes years to grow to reasonable size. Jelly surrounds fresh seed; spread seed and jelly over heavy soil, barely covered, and set the pot itself just below water level. Keep warm, provide ample light. Re-pot into individual pots with first set of real leaves, then pot on as re-quired, always setting top of seedling just below water level

Some species hardy to zone 5; rhizomes should be deep enough that these cannot freeze, or can be removed from shallow ponds or contain-er gardens before freeze-up, and overwintered in wet peat moss. Re-move roots and leaves, and keep at temperatures above 32F/0C and up to 55F/12C, setting them out after the last frost

Tropical species have the same requirements, but do not do well until water has warmed to some 68F/20C. May be grown as annuals in cooler climates. Start these lilies with the crown some 4" below water surface, then set deeper a month or two later; final depth depends on variety. Roots should be covered, but crown must be left bare. Hardy zone 10 only

Nymphoides indica

white snowflake

Aquatic requiring 3-12" water overhead, full sun. May be grown from plantlets on runners removed in spring or early summer, and grown on as N. peltata. Propagate also by division, again as for N. peltata

Nymphoides peltata 

water fringe

Seed or divide rootstock in spring and summer, set 1-2' deep into per-manent location; shallower waters also tolerated. May also set out run-ners, and these plantlets may be removed in early summer, rooted on soil set somewhat below water surface, moved deeper as they mature. Full sun. Zone 5-10

Orontium aquaticum

 golden club

Reproduce from fresh seed in summer, sow onto barely submerged growing medium. Set plants shallowly below water surface, larger plants to 2' deep, tolerates moving water; also grows as marginal in very moist soil. Divide in late spring. Full sun. Zone 6-10

Pistia stratoites

water lettuce, shell flower

This floating aquatic does well in sun to partial shade; peat-rich bog water not well tolerated. Cold areas must be brought indoors to over-winter. Separate new plants from parent as they appear. May also grow from seed when ripe; keep seedlings very moist, 70F/21C. Hardy to zones 9-10

Pontaderia cordata

pickerel weed

Sow seed when fresh and still green, or divide in late spring or early summer. Marginal, tolerating some 6-12" of water overhead; for a sun-ny location. Zone 5-9

Potamogeton crispus

curled pondweed

Submerged aquatic propagated by stem cuttings, spring or early sum-mer, or divide at this time. Wrap base of cuttings with lead strips, allow to sink into soil. Still to slowly moving water, part or full sun. Zone 6-10

Ranunculus aquatilis

water buttercup, water crowfoot

Seed sown ideally when fresh, or at 50F/10C, 1/16" deep; germination irregular and may benefit from stratification; keep very moist and lower germinated specimens gradually to about 12-18" below the water sur-face. Divide in mid, late spring, or take stem cuttings at this time. Tol-erates moving water; may become invasive. Zone 5-10

Ranunculus lingua 

greater spearwort

Sow from seed or divide as R. aquatilis, above. Well-suited as water marginal, may even tolerate a little water overhead; may be invasive, and should be given ample room. Zone 4-9

Riccia fluitans               

crystalwort

Floating aquatic, may be used in the aquarium setting, medium light; tolerates temperatures down to 60F/15C. Zone 10

Sagittaria latifolia

Divide in spring or early summer; also produces turions which may be broken off and relocated in spring. Marginal, tolerates up to 6" of water overhead, needs full sun. Zone 5-10

Salvinia rotundifolia

Floating aquatic which reproduces readily: plantlets may simply be scooped and redistributed. Warm water, good light. Zone 10

Sarracenia species 

pitcher plants

Sow commercially-bought seed in fall or stratify prior to sowing onto moist peaty soil, 70-80F/21-27C or cooler; can take several months to germinate, should never dry out. This bog native is endangered; plants plants should be bought only from reputable dealers. Grow in acidic, wet soils. Some, including S. purpurea, or common pitcher plant, hardy into zone 5

Scirpus cernuus

club grass

Grow in very moist soil, with roots ideally a few inches above water lev-el. Good houseplant, overwinter indoors in cool climates, good indirect light. Divide in spring

Scirpus lacustris

bulrush

Set plant several inches below water surface, or grow in very moist soil. Sunny spot. Divide late spring. Zone 5-9

Sparganium ramosum         

bur reed

Shade-loving marginal, grown in up to 12" of water, propagated by root-stock division in spring. May also be grown from seed sown when ripe. Cold water tolerated well. Also known as S. erectum. Zone 5-9

Trapa natans

water chestnut

This annual floating aquatic regrows from hard, black fruits that sink to the bottom of the pond in fall; in zone 6 or colder, these fruits may be overwintered cool and damp, indoors. Alternatively, start these seeds when ripe in fall, or grow from softwood cuttings. Sun

Typha angustifolia

narrow-leaved cattail

Sow seed in sping. Divide early spring, sharp knife may be required, and set shallowly below water level. Sun, some shade often tolerated. Zone 5-9. T. latifolia, the common cattail, is grown and propagated in the same manner, and is hardy in zones 3-10

Vallisneria species

Propagate by division in spring. These plants are well adapted to low-light aquariums, tolerate cooler temperatures down to about 60F/15C; relatively neutral pH ideal. V. gigantea should be reserved for very large tanks. V. spiralis, or tape grass, produces new plantlets at the base of existing specimens; these may be removed and replanted. Both are hardy to zone 9-10

Water Plants indexed elsewhere

Plants of Home and Garden
Lobelia cardinalis Zantedeschia aethiopia	cardinal flower calla lily, arum lily
Trees & Shrubs Kalmia angustifolia Salix species	sheep laurel willow
Fruits & Vegetables Nasturtium officinale watercress Rorippa nasturtium-aquaticumwatercress
Grains & Grasses Carex morrowii	Japanese sedge