Reed sweet-grass
Glyceria maxima · Poaceae
The gardener's calendar
Ideal time to plant reed sweet-grass: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous
- Flowering
- June to August
- Adult size
- 1 to 2 m in height
- Growth
- Very fast
- Hardiness
- Very hardy (-20°C)
- Origin
- Temperate Europe and Asia
- Soil type
- Moist to waterlogged
Care
Watering
Water grass thrives in moist and marshy environments: it needs constantly waterlogged soil or a spot by the water's edge. In the garden, keep the substrate moist, even submerged during summer. Reduce humidity slightly in winter during dormancy, but never let the soil dry out completely.
Light Exposure
Plant water grass in full sun or partial shade for optimal growth. It tolerates partial shade well, but good light encourages vigor and flowering. Avoid heavily shaded areas that would slow its development.
Soil and Growing Medium
This grass prefers rich, organic soil that is constantly moist, even waterlogged. Add compost or peat-based potting mix to improve water retention. It adapts well to neutral to slightly acidic pH.
Pruning and Cutting
Cut back water grass in late winter (February-March), before spring growth resumes, to a height of 10 to 15 cm. This pruning promotes a dense habit and removes dead foliage. During the season, remove diseased or invasive stems to maintain the desired shape.
Fertilizing
Water grass generally gets enough nutrients from the natural richness of moist soils. A light application of balanced fertilizer in spring (April-May) supports growth if the substrate is poor. Avoid over-fertilizing, which can promote fungal diseases.
Diseases and Pests
Water grass is generally robust in its natural environment. In overly stagnant and warm conditions, root mildews can develop: improve water circulation. Direct pests are rare; however, watch for aphids on young shoots if growing outside its native habitat.
Did you know?
Water grass is highly valued for phytoremediation in retention ponds and degraded wetlands: its dense root system efficiently captures excess nitrates and phosphates, naturally purifying the water. Long ago, its seeds were ground into flour by populations living in the marshy areas of northern Europe, making it a genuine subsistence grain in wetland regions.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
- Tufted hair grassDeschampsia cespitosa
- Wavy hair-grassAvenella flexuosa
- Purple moor-grassMolinia caerulea
- Reed canary-grassPhalaris arundinacea
- Common quaking grassBriza media
- Creeping soft-grassHolcus mollis
Tips generated and checked by Viridia — adapt them to your local climate.