Pennisetum setaceum

Growing in Pots, Balconies & Indoors

Pennisetum setaceum is a sun-loving ornamental fountain grass (reaching about 0.6-1.5 m (24-60 in)), not a houseplant, but it makes a superb container specimen for a patio or balcony. Indoors the light is far too weak for a full-sun grass; give it open air and full sun and it rewards you with arching foliage and plume-like flower spikes.

Quick Details

• Container Size: Start at about 5 L (1.5 gal) for a small clump; for a full, free-flowering plant use at least 15-20 L (4-5 gal).
• Indoor Suitability: Not a houseplant – it needs full sun and open air, so grow it on a bright balcony or patio.
• Best Spot: Full sun; it tolerates light or half shade but then flowers less.
• Soil & Drainage: Good-quality, well-aerated potting mix that drains freely.
• Watering in Pots: Drought-tolerant once established; water more through the flowering season, but the pot must always drain freely.

Indoors & On the Windowsill

• Houseplant limits: The grower is clear this is not an indoor plant – a room’s light is too weak for a full-sun grass, and it needs air movement to look its best.
• Windowsill note: A very bright, sunny sill can hold a young plant briefly, but it will soon want to be outside; treat it as a patio or balcony grass.
• Overwintering: In cold-winter climates a potted plant can be moved to a sheltered, frost-free spot (an unheated porch or garage) for winter and returned outdoors in spring – one of the main reasons to grow tender fountain grasses in pots.

On a Balcony or Patio

• Light & wind: Give it the sunniest position. The plumes sway beautifully, but an exposed, windy balcony can flatten or dry them fast – shelter tall clumps from strong wind. Walls and railings reflect heat, so pots dry quickly; check moisture often in warm weather.
• Practicalities: A large, well-filled pot is heavy – set it in place before filling, and make sure drainage water can escape without staining the balcony.

Choosing the Pot, Soil & Long-Term Care

• Pot & drainage: A 15-20 L pot with strong drainage holes; skip a standing water saucer to avoid root rot. Terracotta breathes and dries faster, while glazed or plastic holds moisture longer.
• Potting mix: A well-aerated potting mix (for example coir or peat with added perlite), as the grower advises.
• Feeding: Potted grasses exhaust their mix faster than plants in the ground, so feed lightly through the growing season.
• Repotting & division: Every few years check the root ball; when roots fill the pot, lift and divide the clump, cut back old roots, remove spent sections and let fresh roots grow, refreshing or replacing tired soil.

Grower’s Container Tip

• Keep it flowering: The grower notes that a fountain grass stops flowering once its roots completely fill the container. Every few years, before it becomes pot-bound, divide the clump – reduce the number of shoots, trim the roots and pot up fresh divisions (or move to a larger container), and if the old soil is tired wash it off and replace it, so new roots and new flowers keep coming.

Bloom & Flower Guide

Quick Details

• Bloom Season: Through the warm season — year-round in frost-free areas, but not in winter where it is cold
• Flower Appearance: Soft, hair-like plumes, white flushed with purple, held in raceme-like spikes above the foliage
• Edibility: Ornamental only — grown for its plumes, not for eating

Detailed Blooming Overview

Fountain grass is grown for its arching, feathery flower heads, which catch light and movement beautifully and fountain out above the leaves. It flowers most freely in full sun. One important caveat: this species is invasive and aggressive, spreading readily by seed, so its bloom is best enjoyed with an eye on containment.

Flower Characteristics

• Fine, hair-like flowers in a soft plume.
• White with a purple hue, borne in raceme-like spikes.
• Wind-pollinated, as grasses are — no pollinators required.

Bloom Care & Thinning

• Feed for bloom: a feed before the flowering season, and a little extra water then, gives fuller plumes — keep drainage sharp.
• Containing self-seeding: because it seeds so freely, removing the plumes before the seed ripens helps keep it from spreading where it is not wanted.
• Tidy-up: cut back dead plumes and old foliage for design, most easily in winter.