This guide is about planting ornamental grasses: clumping garden plants grown for foliage and plumes. If you are looking to sow a lawn, the steps and seed types are different.
When to plant
Spring and early fall are the two usual windows. Planting before summer heat arrives gives roots time to establish before the stress of dry weather.
- Warm-season grasses (such as Miscanthus, switchgrass and fountain grass) are generally best planted in spring. If you are unsure which group yours is in, see warm-season vs cool-season grasses. They grow slowly until the soil warms, and a spring start gives them a full season of rooting.
- Cool-season grasses (such as fescues and feather reed grass) can be planted in spring or in early fall.
- Container-grown grasses can be planted through much of the growing season if you can keep them watered, but summer planting means a lot of watering.
How late can you plant?
For fall planting, a common recommendation is to get plants in the ground at least six to eight weeks before the first frost, so roots can settle before the ground freezes. Planting later than that is riskier, because the plants may not root well enough to survive winter heaving and cold. If you miss the window, one option is to keep the plant in its pot in a sheltered spot over winter and plant it in spring. Our guide to overwintering ornamental grasses covers that situation.
Choosing a site
Most ornamental grasses want full sun, at least six hours a day, and soil that drains well. A few thrive in shade, including Japanese forest grass (Hakonechloa) and many sedges. Check the plant tag for sun needs and hardiness zone.
Think about mature size before you dig. A grass that grows to five or six feet tall and wide in a spot meant for a two-foot plant will cause problems later. Our guide to how far apart to plant ornamental grasses covers spacing by size.
Step-by-step planting
- Water the plant first. Soak the pot well before planting, and keep it shaded while you prepare the hole.
- Dig the hole. Make it wider than the root ball and about as deep as the root ball. If your soil is heavy clay, work in some compost, but avoid enriching it heavily, since rich soil can lead to floppy growth.
- Check the roots. Slide the plant out of the pot. If roots circle the outside, loosen them gently with your fingers or trim the worst of them.
- Set the depth. Place the plant so the top of the root ball sits level with the surrounding soil. Planting too deep can cause the crown to rot.
- Backfill and firm. Fill in with soil, press lightly, and water thoroughly to settle it.
- Mulch. Add a few inches of mulch or compost around the plant, keeping it from piling against the crown.
Aftercare in the first year
Water regularly through the first season so roots grow deep. Check the soil with your finger: if the top inch or so is dry, water; if it is moist, wait. Once the plant is established, many grasses need extra water only in extended dry spells.
Newly planted grasses in fall may benefit from a light mulch over their first winter. You normally do not need to fertilize at planting; see whether to fertilize ornamental grasses.
Plants or seeds?
Nursery plants are the easiest way to get a mature-looking clump quickly. Some species can be grown from seed, and seed of many grasses is sold by specialist and prairie-plant suppliers, but it takes longer. Named cultivars are generally propagated by division rather than seed, because seed does not reliably produce the same plant. Some popular cultivars, such as ‘Karl Foerster’ feather reed grass, are reported to have non-viable seed.
Grasses to be careful with
Some ornamental grasses spread aggressively or self-seed in certain regions, and a few are classed as invasive in some areas. Fountain grass and Miscanthus are commonly mentioned. Spreading types such as ribbon grass can take over a bed. Before buying, check with your local extension office, state or provincial invasive plant list, or native plant society, and consider clumping or sterile cultivars.
Frequently asked questions
What time of year is best to plant ornamental grasses?
Spring is the safest choice for most. Early fall works well for cool-season types and for container-grown plants if there are still several weeks before frost.
Do I need to cut the grass back after planting?
Not normally at planting time. The regular yearly cutback is covered in cutting back ornamental grasses.