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DIVIDING AND POTTING AQUATIC PLANTS

Before you begin, gather your tools and supplies: Containers, dirt, fertilizer, knife, digging tool, scissors, a hose (with a handy shut-off) and of course - towels. If you do not have a potting table or an area designated for the job, use a tarp for a working surface. Choose a cool, shady area for dividing and potting aquatic plants. Use damp newspaper or sheets to cover bare plants to prevent the roots and/or leaves from drying out.

Container: Select squat pots wider than they are tall - they accommodate the horizontal root structure of most aquatic plants, and prevent plants (especially those taller emergents) from tipping over. Sturdy black plastic tubs are ideal. Consider plant size and shelf depth. If you are using pots with drain holes in the bottom, use newpaper or coffee filters to keep soil in the pot until it compacts. Plants used for filtration in phyto- and bio-filters are the exception. For these plants, use mesh pots filled with pea gravel, not soil. This encourages roots to take up nutrients from the water as it passes through.

Soil: All aquatic plants perform the best when grown in heavy soils. Use a chemical free heavy (clay) soil that does not have added organics. Make a mix of 2/3 dirt and 1/3 sand - the sand allows good root penetration and makes it easier for repotting in the future. Do NOT use bagged potting soil - it doesn't compact well, and peat, perlite, manure and other materials float and foul the water. Leave at least 1" at the top of the pot for pea gravel or sand. The main function of the soil is to hold plants in place and provide trace elements as well as some nutrients. By repotting, the new soil will increase the amount of nutrients available to the plant. It also allows for easier fertilization until the plant becomes rootbound again.

Fertilizer: All potted plants require fertilizer occasionally. For best bloom, fertilize lotus and waterlilies monthly during the growing season, twice as often during the hot months (July/Aug.). Begin fertilizing when you see new plant growth. Use a slow-release aquatic fertilizer which comes in tablet form. Place the fertilizer well away from the crown 1/2 to 2/3 of the way into the pot to prevent burning the root. When potting new plants, put the fertilizer near the bottom of the pot before adding more soil and the new plant. Stop fertilizing in the fall when water temps drop into the 60's (except for water hawthornes and trop lilies you want to push for more bloom).

Pea Gravel and/or Sand: These toppings help keep the soil in the pot and prevent fish from mucking up the works as they root in the pots. Be sure to avoid crushed limestone or "road rock" in your pond.

Labels & Marking Pen: It is a good idea to use a new label whenever you pot a plant - include the name of the plant and, for future reference, the date. Use a waterproof marker and insert the tag deeply into the pot, where it will stay and remain hidden.

WHEN??? TIMING IS EVERYTHING !
Early in the spring, before signs of growth, is the best time to divide lotus. Start dividing waterlilies and most other plants in spring as soon as there are signs of new growth. Some, like Pickerel and Thalia, like to get some good growth before being divided - wait until late May/early June to divide these, and consider division every year. Wait to divide Iris until late summer/early fall, so they can store their energy to bloom early the next spring. If you divide them in early spring, they will most likely not bloom that same year.

Since aquatic plants are so resilient, most can be divided throughout the growing season. Be sure to stop dividing in late August/early September to allow the plants to 'root in' before the cool weather sets in.

As a general rule of thumb with marginal plants and submerged aquatics, up-pot until you are satisfied with the pot size, then consider dividing yearly.

WHERE??? PLACEMENT IN THE POND



 

Planting Depths for Aquatic Plants: Place newly potted plants at shallow depths. Once established, move them deeper as indicated below. Plants can be set on blocks to live at their desired depths. The chart below is for during the growing season.

The planting depths below are for during the growing season, and are intended as a guideline. Specific depths are listed for each plant in the Plant List (available at Water's Edge). See the list also for winter plant care. As a general rule of thumb, never submerge more than 1/4 of the height of an emergent plant.

  New Plant Depths Established Plant Depths
Hardy Water Lilies 8" - 12" 12" - 24"
Full Size Lotus wet - 4" wet - 8"
Marginal Plants & Smaller Lotus wet - 2" wet - 2" - 6" (varies)
Lily-Like Aquatics 2" - 6" 4" - 24"
Submerged Aquatics 6" - 24" 6" - 24"

All Planting Depths reflect the distance between the top of the soil and the water surface.

WATERLILIES
Divide hardy waterlilies anytime during the growing season- April thru August. Waterlilies grow rapidly and some can even fill their pot within a season!! Repot your waterlilies when they have jumped their pot or when you can no longer find space in the pot for fertilizer tabs. A good size pot for waterlilies is 16" x 7".

- Gather your tools and supplies.
- Fill the new container 1/2 to 3/4 full with your aquatic mix.
- Place fertilizer tabs near the bottom of the pot.
- Use a Hori-Hori knife or trowel to dig the lily out of its old pot.
- The growing crowns are the tips where new leaves and buds emerge. Find two types of roots - thick anchor roots and hairy feeder roots.
- Clean off most of the soil and cut away the old growth, leaving enough rhisome (2-4") and roots to anchor itself in its new pot.
- Place the cut end of the rhisome at the side of the pot below the soil, with the crown pointing upward towards the center of the pot at a 45 degree angle.
- Put 3-5 crowns in a 16 x 7 pan, for lots of blooms all summer.
- Add aquatic mix to cover roots and most of the rhizome, and top with sand or pea gravel.
- Be sure the crown is well above soil and pea gravel.

 

 

- Gently lower the lily into the pond.

Fertilize lilies regularly throughout the growing season for good bloom.

EMERGENT AND SUBMERGED PLANTS

These plants have a wide variety of growth habits - some grow from rhizomes, others from a central crown, and still others with running stems. In most cases, create a compacted mound of soil about 2/3 the height of the pot. Place the plant on top of the mound, spreading its roots across it. Cover the roots and fill in the pot, gently compacting the soil.

- Divide rhizomes like Iris and Pickerel, and place the cut end against the pot, with the growing end toward the center of the pot.
- Plants with central crowns or stem clusters, single stems, and single crowns can be divided & placed alone or in groups in the middle of the pot.
- Wrap cuttings of runners on plants like Clovers & Pennywort around the mound.

Take 4" stem cuttings from plants like Parrot Feather & Veronica. Place the cuttings half-buried in a full pot. Submerged plants like Anacharis & Cabomba can also be divided in this way.

Fertilize marginals regularly throughout the growing season for good bloom. DO NOT fertilize submerged aquatics. They take in nutrients through their leaves.

THE LOTUS
Divide lotus in the early spring, before there is any sign of new growth. Lotus are extremely vigorous growers. The larger sizes need to be repotted every 2-3 years, and the bowl lotus once a year... Their root structure is a running tuber which, when confined, travels in circles around the inside of its pot.

Use BIG BROAD ROUND TUBS with NO HOLES for your Lotus !

- Use a pot 20-24" x 10-12" or larger for full size lotus.
- Use a pot 14-16" x 7-10" or larger for semi-dwarf.
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Use a pot 8-12" x 5-7" or larger for the bowl lotus.

Pot sizes are important, due to the running growing habit of the lotus, and please - NO square pots - the growing end can get stuck in the corners!!!

- Gather your tools and supplies.
- Put 1" of sand on the bottom of the new container and fill 1/2 to 3/4 full with your aquatic mix.
- Take the lotus out of the pond and carefully dump the dirt/root mass out of the pot, upside down onto a tarp. Growing ends of the lotus protect themselves from winter damage by diving to the bottom of the pot. The best tubers will be found wrapped around the bottom.
- Gently wash the soil off of the tubers and unwind them, discarding the dark and/or mushy ones as you go.
- The life of the lotus is in the growing ends - take care not to damage or bruise them!
- As you expose them, you will see sausage-like tubers, linked together. The "links" are called internodes. . . the nodes are the constrictions between them. New growing ends, leaves and flowers emerge from the nodes.
- Cut through the internodes to make sections that include one or more growing ends (a sausage-and-a-half each). Float these in a tray of water until you are finished dividing.
- Dampen the soil in the container, making it muddy but not soupy. Select one or two of your best divisions and make a shallow horizontal trench for each. Gently lay them in with growing ends pointing up. Cover the thickest part of the tuber with 1-2" of soil. Top all with 1" of sand.

-- Gently saturate the container and lower the lotus into the pond.

DO NOT fertilize lotus until it has standing leaves (late May). Thereafter, fertilize your lotus regularly throughout the growing season. For best bloom, fertilize twice as often during the hotter months - July and August.

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