Water

New Plants (First Year): Water 1 to 2 times per week if there is no rain. Deeply soak the soil around the base so moisture reaches a depth equal to the root ball. Established Plants (Year 2 and Beyond) - Only needs supplemental watering during extended, severe dry spells or heat waves. When it gets extremely dry, give the plant about 1 to 2 inches of water over a 7- to 10-day period. Water the soil at the base rather than overhead. Wetting the foliage frequently can invite fungal issues. Container Plants: If your switchgrass is in a pot, it dries out much faster than ground-planted grass. During the summer, water it 1 to 2 times per week, making sure the top 2 inches of soil are dry before watering again

Fertilizer

Switchgrass naturally thrives in poor, lean soils. Adding fertilizer often does more harm than good to native ornamental grasses. It can cause: 1) Weak Growth: Excessive nutrients—especially nitrogen—cause the grass to grow too fast, 2) Flopping: Fast growth results in weak, weak stems. The grass will flop or fall over instead of standing upright, 3) Loss of Color: Too much fertilizer can wash out the vibrant red and purple fall colors of the 'Cherry Bomb' variety, leaving it dull and overly green. However, if you grow it in a pot, nutrients wash out over time. You can apply a weak, half-strength dose of a balanced, slow-release fertilizer once in early spring.Also, if your soil is completely stripped of nutrients, you can mix a thin layer of organic compost into the surrounding soil in the spring.

Pruning

Cut it back in late winter/early spring, just before new green growth begins to emerge from the base.