redtop
Agrostis gigantea · Poaceae
redtop (Agrostis gigantea) is a perennial grass or grass-like plant in the Poaceae family. It is introduced to North America rather than native. USDA records it as hardy in zone 3 and warmer, down to about -38°F.
At a glance
| Type | graminoid USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | introduced USDA |
| Mature height | 2 ft USDA |
| Light | full-sun USDA |
| Water need | medium USDA |
| Growth rate | rapid USDA |
| Soil pH | 4.5–8 USDA |
| Bloom | April–May USDA |
| Flower color | Yellow USDA |
| Hardiness zones | 3 and warmer USDA |
| Guild layer | herb-layer Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It needs full sun. USDA rates it as having moderate water needs. Its drought tolerance is rated medium. It handles periodically wet ground (USDA rates its anaerobic tolerance medium). It is recorded on soils from pH 4.5 to 8 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 3.
Size and growth
At maturity it reaches about 2 ft, making it about knee height. It grows quickly.
Bloom period
USDA records a bloom period of April through May. Flowers are yellow.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is green, fine in texture. Its flowers are not conspicuous — a plant for form and foliage. Its active growth period is spring and summer. USDA rates its lifespan as short, so plan on replacing or resowing it rather than treating it as permanent structure.
What the site needs to provide
USDA records it across sites receiving 30 to 60 inches of annual precipitation. It needs at least 90 frost-free days to finish its season. It roots to at least 20 inches. Fertility requirement: medium.
Propagating it
Seed is the only propagation method USDA lists. Division and cuttings are not listed as options. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a slow rate. It spreads vegetatively at a rapid rate.
Resilience and wildlife
Browsing animals rate it barely palatable — the sourced basis for calling it deer-resistant. Its fire tolerance is rated high. Its growth form is recorded as rhizomatous.
Role in a guild
Herb layer. In a layered planting this is the herbaceous middle — perennials and grasses that fill the space between ground cover and shrubs. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Agrostis
- velvet bentgrass Agrostis canina
- colonial bentgrass Agrostis capillaris
- spike bentgrass Agrostis exarata
- winter bentgrass Agrostis hyemalis
Similar role and hardiness
- sweetflag Acorus americanus
- calamus Acorus calamus
- common yarrow Achillea millefolium
- western yarrow Achillea millefolium
- meadow foxtail Alopecurus pratensis
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol AGGI2, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, browse palatability, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
Find more plants for your zone with the Plant Finder.