The typical ornamental grass growth rate brings most species to full size in one to two growing seasons after planting. Small types like blue fescue peak within a single year. Larger grasses like switchgrass need two full summers to hit their stride. The tallest species follow the old garden saying: first year they sleep, second year they creep, third year they leap.
I tracked this with my own plants and the pattern held true. When I first put switchgrass in the ground as small one-gallon pots in May, they looked puny. By the end of that first summer, the plants reached about 3 feet tall with thin stems and zero seed heads. I won't lie, they looked sad. Year two changed everything. Those same clumps shot up to 5 feet with thick stems, full foliage, and airy plumes by August. Visitors thought I had pulled out the old plants and put in bigger ones.
Your first-year grasses look thin because the plant focuses on roots, not leaves. During that opening season, roots grow 6 to 10 feet (1.8 to 3 meters) deep into the soil. Building that network takes priority over tall stems and showy plumes. Think of it like building a house. You pour the foundation first and nobody sees it. But nothing above ground stands without it.
So how fast do grasses grow when you look at each species? Blue fescue is the speed champ. It hits full 10 to 12 inch height within one season. Feather reed grass fills out by year two and starts making its upright plumes right on time. Switchgrass takes two years to reach 4 to 6 feet. Big bluestem is the slow giant. It can need three full seasons to hit its peak of 5 to 8 feet (1.5 to 2.4 meters). Each type has its own clock.
You can speed up the ornamental grass establishment time with a few proven moves. Plant with the crown level with the soil surface. Water deep once or twice a week during the first summer to push roots down fast. Don't pile on fertilizer. The University of Florida IFAS says to use no more than 1 pound of nitrogen per 1,000 square feet (93 square meters). Too much food makes weak, floppy stems that fall over in wind.
Give your grasses the water they need in year one. Don't overfeed them. Trust that the roots are doing big work underground even when you can't see it. By year two or three, you'll have grasses that look like they've been in your garden for a decade. Patience is the best tool you have when growing these plants.
Read the full article: 10 Best Ornamental Grasses for Your Garden
