How To Fertilize, Prune And Water Pennisetum Fountain Grasses

Pennisetum grasses, commonly called fountain grasses, are exceptionally easy to grow and care for.

Here's a breakdown of what you need to know...

Fertilizing Fountain Grasses

Fountain grasses are very light feeders. We recommend feeding at planting time and thereafter annually in spring with a mild organic plant food. Plants in containers require only one feeding per year as well.

Soil pH - Fountain grasses grows grow best in a moderately acid to neutral soil ranging from 5.5 to 7.0 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.5.

Testing Soil pH  Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or suspect your soil is not suitable for growing fountain grass, it's a good idea to test the pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.

Watering Fountain Grass

Fountain grasses prefer a moist but well-drained soil. When established they can tolerate dry periods but require a moist soil when becoming established. As with many other ornamental plants, they do not like constantly soggy or wet soil, which can lead to root rot and other plant diseases. So be careful not to overwater!

After Planting 

Immediately after planting deep soak the soil in the planting area to a depth of at least 6 inches. An application of Root Stimulator will provide an extra boost to stimulate early root formation and stronger root development, which reduces transplant shock and promotes greener, more vigorous plants.

During the First Active Growth Season

In average garden soil you should not have to water your newly planted fountain grasses every day. More often than not, this causes soggy soil conditions that can lead to root rot and other plant diseases. In the absence of sufficient rainfall, water only as needed to keep the rootball and surrounding soil damp to moist. Keep in mind that deep soaking less frequently is much better than splashing just a little water on the plants every day. Plants planted during the winter dormant season, when not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!


When established, fountain grasses are quite drought tolerant. During prolonged periods of summer drought plants will appreciate occasional deep soakings. If you see foliage wilting or discoloring check soil moisture and give plants a good deep soaking if necessary.

Watering Fountain Grasses In Containers

Fountain grasses growing in containers will require closer attention to soil moisture. Check soil moisture regularly and provide water if the top inch or two of the soil is somewhat dry to dry. During cooler months fountain growing in containers will not require as much water.

Important Tip:  When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliage diseases. During the first few weeks after planting, check soil moisture often and adjust irrigation time if necessary to keep the soil moist, not wet.

Pruning Fountain Grass

In frost-free climates, fountain grasses don't require much if any pruning. 

In cold climates where fountain grass dies back during winter, foliage can be cut back to just above the ground (or soil in pots) any time between after they've gone totally dormant, to late winter, before new spring growth has begun to emerge.

Regardless of climate, damaged or broken leaves and/or flower stems can be removed at any time during the growing season.

Plant Long & Prosper!

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