Water Garden Problem Solving: Planting Deep Ponds, Controlling Reedmace, and Soil Mixes

Expert Solutions for Common Water Gardening Challenges

Planting Water Lilies in a Deep Natural Pond

Q: "I have a large natural pond 90cm+ deep at center. What water lily varieties and planting method?"

A: Standard baskets are useless on an earth bottom. Choose depth-appropriate varieties with distinct foliage for easy identification if they merge: 'Gladstoneana' for deep zones, 'Marliacea Chromatella' for shallower areas. Plant by hand or from a boat: strip all foliage except a tuft of submerged leaves on the crown. Wrap bare-root plant with generous soil in a 30cm (12in) hessian square, tie securely, and lower into position. The hessian rots as roots penetrate the bottom soil, forming large colonies.

Controlling Invasive Reedmace in a Lined Pond

Q: "Reedmace is invading adjacent plants. Pond is lined with soil cover; can't dig without damaging liner."

A: Two options: (1) Cut reedmace below water level in late summer—hollow stems fill and rot. (2) Use glyphosate herbicide (absorbed by foliage, harmless to aquatic life). First, sever the rhizome at your desired boundary with a sharp knife (rhizomes are just below mud surface—doable without liner damage). Treat only the detached portion. Remove dead foliage to prevent pollution; rhizome decays harmlessly in mud unless disturbed.

Traditional vs. Modern Water Lily Soil Mixes

Q: "Old books recommend turf and rotted cow manure—won't that turn the pond green?"

A: Yes. That method worked but caused green water until nutrients exhausted—by which time lilies were also starving. Modern approach: clean, heavy garden soil or aquatic compost (no artificial fertilizer, low organic matter). Add slow-release fertilizer tablets/sachets beside plants so they absorb nutrients before leaching occurs. Better for plants, better for pond ecology.

Rock Garden Plants for Waterfall Splash Zones

Q: "Plants that tolerate constant splashing from a waterfall?"

A: Most rock plants hate constant damp. Alpine ferns excel: maidenhair spleenwort (Asplenium trichomanes), wall rue (Asplenium ruta-muraria), hardy maidenhair fern (Adiantum pedatum), and polypodies (Polypodium vulgare and cultivars)—especially with organic-rich soil pockets. Musks adapt well: 'Highland Pink', 'Highland Red', vivid 'Whitecroft Scarlet' (some need annual reseeding). Yellow Mimulus luteus also thrives in damp rock crevices.