Ornamental grasses are the unsung heroes of the summer garden. They sway in the breeze, catch the golden afternoon light, and by late summer can transform a plain backyard into something that looks straight out of a design magazine. But here’s the thing — the difference between grasses that peak with glorious, feathery plumes and grasses that flop, look patchy, or never quite fill out? It almost always comes down to what you do (or don’t do) in June.
June is prime time for ornamental grasses. They’re actively pushing new growth, and the care you give them right now sets the stage for everything that comes later in the season. Here are 10 essential tasks to do this month to get the most dramatic, lush plumes possible.
1. Finish Any Late Division — Now, Before It’s Too Late
If you noticed last year that some of your grasses were dying out in the center or getting too large for their spot, early June is your last realistic window to divide them. Once temperatures climb and the grass is in full summer growth, dividing becomes much harder on the plant (and on you).
Dig up the clump, cut it into sections with a spade or old saw, and replant with plenty of compost worked into the soil. Water deeply after replanting and keep the soil consistently moist for the first two weeks.
2. Give Established Clumps Their Summer Feeding
Ornamental grasses are not heavy feeders, but one well-timed application of a balanced, slow-release fertilizer in early June pays dividends all season. Look for something around a 10-10-10 or similar ratio. Avoid high-nitrogen feeds — too much nitrogen pushes soft, floppy leaf growth rather than strong, upright stems that support those tall plumes.
Sprinkle granular fertilizer around the base of the clump (not on top of it) and water it in well.
3. Water Newly Planted Grasses Consistently
Established ornamental grasses are famously drought-tolerant — but “established” is the key word. If you planted new grasses this spring, they need consistent moisture through their first summer to develop a deep, resilient root system.
Water new plantings two to three times per week in dry weather, making sure water penetrates at least 6 inches into the soil. A slow, deep watering is always better than a quick sprinkle.
4. Clear Out Winter Debris From the Base
If you cut your grasses back in early spring, there’s often old leaf litter, dead stems, and debris still caught in the base of the clump by June. Take a few minutes to gently comb through with gloved hands or a hand rake and remove anything that’s packed in there.
This improves air circulation around the crown, which helps prevent fungal issues during humid summer months — a real problem for some grass varieties in warm, wet climates.
5. Stake Tall Varieties Before They Need It
Some of the showiest ornamental grasses — Miscanthus, Pampas grass, giant feather grass — can reach 6 to 10 feet tall by late summer, and their plumes get heavy. If your garden gets summer storms or strong winds, it’s far easier to put a simple ring stake or bamboo support in place now, while the plant is still growing into it, than to try to prop up a leaning clump in August.
Install stakes so they blend into the emerging foliage and the grass grows up through or around them naturally.
6. Mulch Around the Base (But Not Over It)
A 2–3 inch layer of mulch around your ornamental grasses does triple duty: it retains soil moisture, suppresses competing weeds, and moderates soil temperature during summer heat spikes.
Keep the mulch pulled a few inches away from the crown of the plant. Mulch piled directly against the base can trap moisture against the crown and encourage rot, especially during hot, humid weather.
7. Address Any Fungal Rust or Leaf Spot Early
Warm, humid June weather creates ideal conditions for rust and leaf spot diseases on some ornamental grass varieties, particularly on plants that are crowded or in low-airflow spots. Look for orange or brown pustules on leaves, or irregular brown blotches.
Mild cases often resolve on their own as summer heat dries out. For persistent problems, remove and bin (don’t compost) affected foliage, and consider thinning crowded clumps to improve airflow. Avoid overhead watering in the evening.
8. Remove Spent Flower Heads From Spring-Blooming Varieties
Some grasses, like Blue Oat Grass (Helictotrichon sempervirens) and certain Stipa varieties, produce their best display in late spring and early summer. Once those flowers age and the seed heads start looking tired and brown, snipping them off keeps the clump looking tidy and can actually encourage some grasses to produce a second flush of growth.
For most summer and fall bloomers — like Miscanthus and Panicum — leave the developing flower stalks completely alone. They’re building the plumes you’ve been waiting for.
9. Keep Weeds Out of the Clump’s Center
Opportunistic weeds — especially grassy ones like crabgrass — love to sneak into the center of ornamental grass clumps where they’re easy to miss. Once established inside the clump, they’re a nightmare to remove without damaging the grass itself.
Do a careful inspection in June and pull any intruders by hand while they’re still small. If you find a persistent weed grass species growing through an ornamental clump, the best long-term solution is often to divide the ornamental grass, clean the sections thoroughly, and replant.
10. Plan Now for Late-Season Impact
June is also the perfect time to walk your garden and honestly assess where you want more grass presence for fall. Ornamental grasses planted in June from potted nursery stock still have enough of the growing season to establish and look great by September — especially fast-growers like Panicum (Switchgrass) and Pennisetum (Fountain Grass).
Think about where you want movement, texture, and those beautiful backlit plumes in autumn. Order or buy now while garden centers still have good selection, before the summer rush clears shelves.
A Little June Effort, a Lot of Fall Drama
Ornamental grasses reward almost any effort you put in during their active growing months. The tasks above take only an afternoon or two spread across June — but come August and September, when those tall plumes are swaying in the breeze and catching the late-day sun, you’ll be glad you took the time.
Whether you’re growing a few clumps as accent plants or building a full meadow-style border, June is your most valuable window. Get out there and make the most of it.
