A tall, thick grass plant can add height, privacy, movement, and a soft screen to a garden or large container. Success depends on choosing a grass suited to your climate and space, then giving it the right light, soil, water, and room to mature. This guide explains how to select and establish an ornamental grass; check the plant label first because care varies by species.
What You’ll Need
- A suitable grass plant or division from a healthy, correctly identified plant
- A planting area with enough space and the light conditions the variety needs
- A spade or trowel, garden gloves, and water
- Compost or other soil amendment only if a soil test or poor soil condition indicates it is needed
- Mulch, such as shredded bark, if desired
- For a container: a pot with drainage holes and quality potting mix
Step-by-Step
- Choose the right kind of grass. “Tall thick grass plant” describes a look, not one botanical species. Compare mature height and width on the plant label, and check whether the grass is evergreen or dies back in winter. Select a clumping variety for a contained feature. Running grasses can spread aggressively, so avoid them where they may invade neighboring beds or natural areas. Confirm the plant is hardy in your local climate.
- Match the plant to the site. Check the label for sun and moisture needs. Many popular ornamental grasses grow best in full sun, but some tolerate part shade. Make sure the spot drains well unless the selected species specifically prefers wet soil. Keep the grass clear of paths, windows, utility access, and overhead obstructions, allowing for its mature width as well as height. Avoid planting where its dry leaves could create a fire hazard near structures.
- Prepare the soil and timing. Plant in spring or early fall when conditions are mild and the soil is workable; spring is often best in cold-winter regions, giving roots time to establish before freezing weather. Remove weeds and loosen soil across the planting area. Improve very poor soil with a modest amount of finished compost, but do not routinely add fertilizer or create a rich pocket in otherwise poor-draining ground. If you are unsure about drainage or pH, use a soil test.
- Water the root ball before planting. If the nursery potting mix is dry, water the plant until the root ball is evenly moist and let excess drain. Slide it from the pot and inspect the roots. Gently loosen circling roots with your fingers; if they form a dense mat, make a few shallow vertical cuts around the sides. Handle the crown—the point where stems meet roots—gently and keep it intact.
- Dig and set the planting hole. Make the hole about twice as wide as the root ball and no deeper than its height. Set the plant so the top of the root ball is level with, or just slightly above, the surrounding soil. Do not bury the crown. Backfill with the excavated soil, firming lightly to remove large air gaps without compacting it hard.
- Water thoroughly and mulch. Water slowly at the base until the whole root zone is moist. Add a 2- to 3-inch layer of mulch around the plant to limit weeds and reduce moisture loss, leaving a few inches clear around the crown so it does not stay damp or rot. In a windy or exposed spot, make sure the root ball is firmly settled and water again if soil has pulled away from its edges.
- Establish the grass with regular checks. During the first growing season, check soil moisture every few days at first, then adjust to rainfall, temperature, and drainage. Water when the soil a couple of inches down begins to dry, giving a deep soak rather than frequent shallow sprinkles. Do not leave roots waterlogged. Once established, many ornamental grasses need less frequent watering, but drought-tolerant does not mean they never need water.
- Maintain it according to its type. Remove weeds and replenish mulch as needed. Do not shear every grass in fall: many look attractive through winter and their standing foliage protects the crown. For deciduous grasses, cut back dead foliage in late winter or early spring before new shoots appear, leaving a short bundle above the crown. Wear gloves and use clean, sharp tools; stiff leaves can cut skin. Evergreen grasses generally need selective removal of dead leaves rather than a hard cutback. Divide crowded clumps in spring if the species benefits from division.
Common Mistakes
- Choosing by appearance alone: A small nursery plant may become much wider or taller than expected. Check mature dimensions before planting.
- Planting too deep: Buried crowns can stay wet and decay. Keep the crown at soil level.
- Overwatering or poor drainage: Constantly wet soil can damage roots, even when the foliage looks thirsty. Check soil moisture before watering.
- Overfeeding: Excess fertilizer can encourage weak, floppy growth. Feed only when the species or a soil test calls for it.
- Cutting back at the wrong time: Cutting deciduous grasses in fall removes winter structure, while cutting evergreen types to the ground can seriously injure them. Identify the grass first.
- Ignoring spread: Some grasses spread by underground runners or self-seed. Research the variety and remove unwanted seedlings before they establish.
Tips
- Plant in groups for a fuller screen, spacing plants according to their listed mature width rather than crowding them together.
- Use a tape measure to mark the planting area and visualize mature height from nearby windows and paths.
- For a container, choose a heavy, frost-resistant pot with drainage holes. Water more often than an in-ground plant, since pots dry out faster, and protect the container from severe winter cold where needed.
- Photograph the plant label or note its botanical name. That makes it easier to find accurate pruning, dividing, and watering guidance.
- If the grass is unfamiliar, check whether it is considered invasive in your region before buying it.
Troubleshooting
- Leaves turn brown soon after planting: Check moisture in the root ball, not just the surrounding soil. A dry root ball may repel water, while soggy soil suggests poor drainage. Water deeply when dry; improve drainage or relocate the plant if water stands for long periods.
- The plant wilts despite damp soil: Stop watering and inspect drainage. Wilting in wet ground can indicate root stress rather than thirst. Make sure mulch is not piled over the crown.
- Stems flop or split: The site may be too shady, the plant may be overfertilized, or the clump may be too crowded. Check the variety’s light needs, avoid unnecessary feeding, and divide or relocate it when appropriate.
- Growth is sparse or slow: Give the plant time to establish, remove competing weeds, and verify its sun and water requirements. If it remains weak, check for root damage, poor drainage, or a plant unsuited to the climate.
- The center dies while the edges grow: The clump may be old and congested. Divide it in the recommended season, keeping healthy outer sections and discarding dead or woody centers.
Frequently Asked Questions
How fast does a tall ornamental grass grow?
It depends on species, climate, and establishment. Many take one or more growing seasons to reach a strong mature clump; use the plant label for expected size and do not crowd it to speed up screening.
How much sun does a tall grass plant need?
Many ornamental grasses prefer at least six hours of direct sun, but requirements vary. Follow the label; a shade-loving or shade-tolerant species may perform better in a less sunny spot.
Should I cut grass plants back in fall?
Usually not for deciduous ornamental grasses. Leave their foliage until late winter or early spring, then cut back before new growth. Evergreen grasses are generally tidied selectively instead.
Can I grow a tall grass plant in a pot?
Yes, if the variety’s mature size suits the container. Use a stable pot with drainage holes and quality potting mix, and expect to monitor water more often than for plants in the ground.
Why is my grass plant not growing tall?
It may be young, planted in too much shade, short of water during establishment, or poorly suited to the site. Compare its conditions with the label and allow time for roots to develop.
Can ornamental grass be divided?
Many clump-forming grasses can be divided, commonly in spring, but some do not respond well. Confirm the species’ preferred season and method before digging up the clump.