Purple fountain grass (Pennisetum setaceum ‘Rubrum’) is a highly favored ornamental grass that provides striking color and texture to the landscape. This warm-season grass features arching, burgundy-red foliage, giving it a graceful, fountain-like shape. Fluffy, bottlebrush-like flower spikes emerge purple-pink or copper-colored in summer and fall. Its appeal lies in its dramatic appearance and ease of growth, making it a popular, low-maintenance choice.
Site Selection and Optimal Timing
Successful establishment begins with selecting the correct site, which influences the plant’s health and the intensity of its coloration. This grass thrives in full sun, requiring six to eight hours of direct sunlight daily for the most vibrant foliage. Insufficient sun results in a less intense color, making the leaves appear greener.
The soil composition is equally important, as the plant necessitates a well-draining environment to prevent the crown and roots from rotting. Although adaptable to many soil types, loamy soil provides the best results. If the planting area has heavy clay soil, it should be amended with organic material like compost or aged manure to improve drainage and aeration.
As a warm-season grass, planting should occur after the last spring frost has passed and the soil has warmed sufficiently. The ideal window is typically in the late spring or early summer. This timing allows the grass to establish a strong root system during the peak growing season, avoiding cold stress that hinders development.
Preparing the Plant and Soil
Preparing both the planting site and the plant facilitates immediate root growth. Begin by clearing the selected area of any weeds, stones, or debris that could compete for nutrients and water. Loosen the soil in the entire planting area to a depth of 12 to 15 inches, which helps the new roots spread easily.
The planting hole should be dug two to three times wider than the root ball, but no deeper than the root ball’s height. Digging a hole that is too deep can cause the plant to settle too low, leading to water accumulation around the crown. Prior to transplanting, gently water the grass in its container to ensure the root ball is moist and reduce transplant shock.
Carefully remove the grass from its container and inspect the root ball for circling or tightly matted roots. If the roots are heavily bound, use your fingers or a clean, sharp tool to gently tease them apart or make a few shallow, vertical cuts down the sides of the root ball, known as scoring. This action encourages the roots to grow outward into the surrounding garden soil, promoting better anchoring and nutrient uptake.
Step-by-Step Planting and Initial Watering
With the planting site and grass prepared, position the plant correctly in the ground. Place the purple fountain grass into the center of the prepared hole, ensuring the crown—where the roots meet the stems—is level with or slightly above the surrounding soil line. This slightly elevated placement prevents water pooling around the base, which is a common cause of crown rot.
Begin backfilling the hole with the excavated soil, working it around the root ball to eliminate large air pockets. Gently tamp the soil as you fill to settle it and ensure good contact between the roots and the surrounding earth. Do not pack the soil down too firmly, as this impedes water and air movement necessary for root development.
Once the hole is filled, form a shallow, circular basin of soil around the newly planted grass, just outside the root zone. This basin directs water straight down to the roots during initial watering. Immediately after planting, water the grass deeply and thoroughly until the entire root zone is saturated, which further settles the soil and removes any remaining air pockets.
For the first few weeks following planting, maintain a consistent watering schedule, ensuring the soil remains evenly moist but never waterlogged. This period is crucial for the grass to establish its new root system. It often requires about an inch of water per week, depending on local rainfall and temperature. Allowing the top layer of soil to dry slightly between waterings encourages the roots to grow deeper, setting the stage for the plant’s future drought tolerance.