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by Kerri Bailey, revised 3/20/18
Water or aquatic plants are essential features for any pond or water garden. They add beauty and color softening the rocks, while providing shelter for fish. The bonus is that they also help keep your water clear and fish healthy. Water plants also compete with algae for nutrients and consume excess fish waste. So you may want to add more plants to your pond to increase your filtration and pond appeal.
What are Water Plants?
So, what are water plants? They range from plants that tolerate wet feet and areas to plants that can be completely submerged in water. These plants can survive and thrive in wet areas year round (or naturally for their life cycle). Many common garden plants can be used in ponds or bogs that grown along the edges (margins) and stream areas. When plants are grown in water, they produce a different type of roots than soil grown plants. Aquatic roots are long and filamentous with feathery looking root hairs. These roots grow into the water for searching for nutrients, oxygen and are used to anchor themselves. Some plants float on the waters surface that have air bladders inside their leaves or stems to keep them buoyant with roots that grow completely submerged.
Water Plant Groups
Water plants are classified into four main groups: “Water Lilies and Lily-Like”, Marginals, Floaters and Submerged plants. Each plant group is dependent upon where they grow in the pond or how deep they can be submerged in water.
Water Lilies are the jewels of the pond. The root or rhizome grows in deep water (1′-4′) with stems that grow upward toward the water surface. Leaves and flowers float on the water surface or slightly above. Water lilies are divided into two types- Hardy and Tropical. Hardy Water Lilies are hardy from zones 3-9 and can be grown just about anywhere in the country year round. They typically are day bloomers that are available in many colors with leaves and flowers that float on the waters surface. Tropical Water Lilies need warmer temperatures (above 65ºF) and are usually treated as annuals or winterized inside. They come in vibrant bloom colors with leaves and flowers that stand out above the waters surface. They are either day or night blooming. Check your zone at: http://planthardiness.ars.usda.gov/
Lily-Like Aquatics Grow similarly to hardy water lilies but have smaller leaves and flowers, and grow in shallower water depths. They are very versatile working well in containers and in small ponds. The lily-likes vary in leaf size and shape, temperature hardiness and flower form.
Marginal Plants A very large group of plants that grow on the margins of ponds, bogs or stream edges. They are grouped as hardy or tropical- hardy plants survive below zone 9 and tropicals survive above zone 9. Iris & Cattails are hardy marginals and Taro & Papyrus are tropical marginals. Some marginals can survive in wet soil to a few inches of water depth, and others can grow deeper (up to a foot of water).
Floating Plants or Floaters Plants that float on the waters surface with their roots submerged into the water. Their leaves have air bladders that keep them buoyant. Most are annuals ( Water Hyacinths, Water Lettuce) some are hardy (Azolla, Frogbit)
Submerged Plants What most people think of as “water weeds”.
They are often referred to as “oxygenators” which is misleading, as all water plants consume and produce oxygen. These plants are found under the water surface either freely floating or anchoring themselves to the bottom. At times they may grow at the waters surface or out of the water. Most have insignificant flowers, others have delicate blooms. Many are considered “noxious weeds” so check the list to see what you can grow in your state http://plants.usda.gov/java/noxious?rptType=Federal
WA State see: http://www.nwcb.wa.gov/ab_weedlaw.htm
Kerri Bailey, owner of The Pond Pad, has been working with aquatic plants and herbs since 1989 and has been in the pond and horticulture industry since 1998. She has a BS in Biology and is a Certified Herbalist.
Placement: Full sun, up to 6 hours of sun a day for abundant blooms, although there are a few varieties that can take less sun (Burgundy & Dark Red colored varieties can fade in too much sun). Water lilies do best in moving water that is oxygenated by a pump, stagnant water may cause them to rot out. Avoid water splashing on the leaves, and heavy wind & wave action that causes leaves to pull away from stems.
Water Depth: Water lilies are submerged plants- the roots need to be in the water with theleaves floating on the top of the water. The roots or pot should be submerged at least in a foot of water up to 2.5′ / 3′. Dwarf varieties can be in less water, the larger ones should be grown in deeper water. In natural ponds that have stiller water, water lilies can grow in up to 6′ water depth. If lilies are planted too deep, the stems can break away from the rhizome (tuber).
Fertilizing: Fertilize your water lilies around April or May, monthly until August/September. Do not fertilize your plants when they are dormant and follow the directions on the package. Use only aquatic fertilizer tablets- not fertilizer meant for soil plants- you can get algae blooms and possibly kill your fish. You don’t have to fertilize them if you have a heavy fish load, the fish waste turns into nutrients for the plants to absorb. If your lilies aren’t blooming, they may need to be divided, re-potted or need fertilizer.
Dividing: Divide mature plants when overcrowded, or have out grown their pot. In warmer areas, divide your lilies more often, cooler areas divide less often (shorter growing seasons) or every 3-4 years in late spring. If you clean out your pond, that would be a great time to deal with your aquatic plants-dividing, fertilizing, cutting back foliage, etc. Water Lilies planted directly into the pond may need to be divided every 2-3 years as they will grow faster than they will potted. A divided water lily needs at least 6 weeks of good growing weather in order to survive winter. Use a sharp, clean knife and cut 4″-5″ of rhizome on medium to large types and 2″-3″ pieces on smaller types. Make sure there is at least 1-2 side eyes per division.
Planting:Plant your water lily directly into the pond, or submerge a potted lily in 1′-3′ ofwater depth. Do not use a planting mix, potting soil or compost intended for soil plants. These mixes use a lot of oxygen as they break down and can cause your tuber to rot or cause algae blooms. Use an inert medium- top soil, sandy loam, gravel or an aquatic plant “soil”. See my blog on Planting Hardy Water Lilies for more details.
Pest Control: Water lilies get few pests & diseases. Aphids can be a problem and can spread quickly. Never use a pesticide on any pond plant that is not labeled safe for aquatic life- fish are very sensitive! A natural method is to coat the leaves of the lily infected with aphids with “Diatomaceous Earth”or DE- a whitish powder make up the shells of microscopic organisms called diatoms (avoid breathing in the dust particles).
The sharp edges of the diatoms cut the insects and suffocate them. Wait a day and spray off your lily pads with a gentle stream from a garden hose. You may have to repeat this several times until they are gone. The fish may eat some of the aphids for you and the DE will not harm fish. Another potential problem is root rot, which usually happens to potted lilies.
Dead Heading / Leaf Care: Each water lily bloom lasts up to 5 days or so, opening and closing each day until it expires. You can cut spent flowers to stimulate more blooms and to keep your lilies tidy. Dead or ugly leaves can be trimmed as needed. Do not cut the “indicator” leaves that grow out from the base of the tuber, they tell the plant when to grow in the spring.
If you have any questions email at: firstname.lastname@example.org or stop by ThePondPad.com. Kerri Bailey, owner, has been working with aquatic plants since 1989 and in the horticulture & pond industry since 1998. She has a BS in Biology and is a Certified Herbalist. See her other blogs on Planting Hardy Lilies and Water Lily Facts.
What supplies you need to clean your pond:
- A Pump with pipe to evacuate (remove) the pond water
- A Skimmer net to filter debris
- Hose, running water and a strong nozzle (pressure wash with caution)
- Scrub brush and /or scrub pads
- An algaecide like Quick Fix (or several bottles of peroxide)
- Container for fish with a cover (net) and aeration (pump or air stone)
- Fish nets and/or tubs to remove fish from pond water
- Rubber boots (shoes) and gloves are optional (I usually don’t wear gloves)
- Beneficial bacteria, plant fertilizer tablets, water conditioner
Step One: Turn off all pumps, filters, etc. Place your clean out pump in the deepest part of your pond; plug it in and start to remove the pond water (drain into a garden or lawn area). If you have fish, they need to be removed and kept in a tub or large container (keep out of direct sun) . Fill it 2/3 with the pond water you are removing, before pond is empty. Continue to drain the pond, leave little water, just enough to catch your fish. Clean filter pads while you wait.
Step Two: Catch your fish, carefully! Use a net to catch small fish and place them in the container with pond water. Larger fish should be caught with a tub or fish bag / sock as they can flop around inside of nets and could be injured. Keep the water with the fish aerated with a small pump or air stone and cover with a net- koi love to jump. Check your fish often for signs of stress. Treat any fish that may be “sick” or have parasites with an appropriate medication.
Step Three: Remove any potted plants and any plants that need to be divided. Store them in tub with water away from the direct sun. Cut back any plants that remain in the pond and any other maintenance that needs to be done-clean skimmer and debris net/basket. Divide plants and re-pot those that are pot bound.
Step Four: Use your hose and a strong stream of water and spray down the stream and waterfall area, washing the debris into the pond. Continue to remove the water with your pump. Then work your way to the pond and spray down the side walls and shelves. This may take up a while- hours for a large pond. Sprinkle some Quick Fix powder on the falls and any other area where there is an algae or green build up.
Use your skimmer net to scoop out debris, leaves and muck. Use your scrub brush to remove scum from rocks. When the water your pump out is almost clear, then you can stop “cleaning” and start to fill back up again. You don’t have to get rid of every speck and have sparkling clean rocks. The brown film on the rocks is beneficial bacteria and is a good thing. If you remove it all, then you may have “green” water in the summer. it takes time for the bacterial colonies to grow keeping the pond balanced.
Step Five: Put your pond plants back into the pond, fertilize any that may need it- water lilies are heavy feeders. Now is the time to fix any rocks or rearrange as needed. Remove clean out pump and start to fill your pond. This may take several hours. Put the clean filter pads and filter media back in the filter; put debris net/basket back in the skimmer. Once the water is half to 3/4 full, add water conditioner (unless you have untreated well water) and beneficial bacteria.
Step Six: Time to put your fish back into the pond, very carefully…..releasing them gingerly. Continue to fill the pond with water until it is at it’s normal level. Your fish may hide for a few days and may not want to be fed right away. Monitor them closely for the next several days. Add beneficial bacteria like Organic Digester by Strata on a regular basis to help keep your ecosystem clean, clear and healthy. Enjoy!
Kerri Bailey is the owner of The Pond Pad water garden online store and maintenance service. Kerri has been working with aquatic plants and herbs since 1989 and has been in the horticulture and water garden industry since 1998. She holds a BS in Biology and is a Certified Herbalist.