Dwarf Sag (Sagittaria subulata)
Dwarf Sag is a very small but very useful submerged plant in pond and aquarium. Growing from 2"-6" tall with narrow leaves, it looks just like an underwater lawn of grass.
Growing underwater and planted on the bottom of the pond, dwarf sag isn't normally bought for its ornamental value (except in aquariums, where it it really cute!). Instead, dwarf sag is popular in ponds because it is a powerhouse of a little plant--growing rapidly, dwarf sag oxygenates water during the day and absorbs nutrients as it grows, purifying and clarifying the water.
Dwarf sag needs to be planted in soil or pea gravel, either in pots or on the bottom of the pond. Sometimes planted right into waterlily pots with the waterlilies, it won't crowd out waterlilies and shares the pot space, even helping keep the pot soil aerobic while the waterlily is dormant in winter (good for the waterlily!). Landscapers often plant hundreds on these in the pond bottom as part of the filtration for the pond, and that helps keep the pond ecosystem in balance.
Dwarf sag will grow shorter in full sun and shallow water, especially in very clean water. It will grow taller in partial shade and deeper water. Dwarf sag may be planted in very shallow water of just a few inches, and can adapt (slowly) to growing partly out of water when in water just an inch or so deep. Dwarf sag may also be planted in deep water, the only depth limit being that they do need to get some light, so if the water is clear and the pond bottom still gets some light 15' deep, dwarf sag can grow that deep. In shallow water (where the plant can send its flowers above the surface), dwarf sag shows off small white blooms with yellow centers.
Dwarf sag co-exists pretty easily with goldfish, but should be well established before trying them with koi, as koi nibble harder on plants. With koi the more plants you have the better your success rate, and they are very good for the koi's diet as well.
Dwarf sag does very well in aquariums, and is one of the hardiest "groundcover" foreground plants you can use in high or low light aquarium conditions.
Sold singly as bare root plants. Dwarf sag is very small so expect to receive small plants with 2 or more leaves per plant. When planting, do not plant in a tight clump--allow at least 1/2" between plants, and anchor them firmly so they stay planted while their roots are growing out.
Hardiness Zone: 4-11, evergreen and active so long as planted below the ice level
Planting Container: See plant description
Light Requirements: full sun to part shade
Height: 2" to 6" - Spread: Running
Water Depth: See plant description