close-up of subterranean clover

Subterranean Clover

Trifolium subterraneum L

Subterranean clover is an annual clover that produces a thick cover in areas with Mediterranean-like growing conditions.

Easy to recognize.

Subterranean clover, or simply “sub clover”, is a low-growing annual that forms a dense cover due to a low growth habit and extensive stolons and leaves. This makes sub clover an excellent weed suppressor, even better than vetch. Due to its low growth habit it can even produce seed under heavy grazing pressure which is an added bonus to insure reseeding in grazed pastures.

Sub clover leaves are easy to recognize being heart-shaped and hairy with the majority bearing a black spot. It possesses small white flowers that give rise to a large, “burr” type seed bearing structure that has a unique ability to force itself into the soil thereby actually reseeding itself. Its seed are also the largest of the commercially available clovers.

Grows in wet conditions.

Tens of millions of acres of sub clover have been planted in Australia and it has become one of the most important legumes in that country’s grassland agriculture. In North America, sub clover it is best suited to climates that have mild, wet winters; especially in states like California, Oregon and Washington. It has also shown good performance in southeastern Coastal Plain area from southern Texas to Florida. Sub clover is generally more tolerant of low fertility and shade than most clovers. It is best adapted to heavier textured soils with good moisture holding capacity. A pH of 5.8-6.5 is recommended for optimal performance.

Good eating.

Sub clover makes most of its growth in mid-spring, but its total seasonal yield is usually not as high as arrowleaf clover, berseem clover, or crimson clover. Sub clover can produce between 3,000-8,500 lbs. DM/A annually as a thick mat of leaves, stems and petioles.

Nitrogen producer.

Sub clover can contribute up to 200 lbs. N/A making it very useful as a short rotation cover crop and annual pasture component. In order to achieve optimal nitrogen fixation ability, subterranean clover needs to be inoculated with Rhizobium leguminosarum biovar trifolii. This is best achieved with Nitro-Coat®.

What we recommend.

Most subterranean clover is sold as variety not stated.

Subterranean Clover Specifications

Subterranean Clover Specifications

Planting
zonesZones 8-9
annual/perennial/biennialAnnual
ease of establishmentExcellent
seed/lb70,000
seeding rate straight10-20 lbs/ac
seeding rate mix8-15 lbs/ac
seeding timeSeptember-early November
seeding depth3/8-1/2 inch
seeding methodBroadcast or drilled (preferred)
method of killing/suppressionMowing; grazing; chemical
optimal germination temperatureNight temperatures >50 F
seedling emergence/vigorExcellent
reseeding potentialExcellent
root typeTap
Usage
grazing potentialExcellent
hay potentialPoor
use with wildlifeGood
use in orchardsGood
use with row cropsExcellent
use with other grasses/legumesExcellent
Bees/benefitial insectsFair
compaction controlGood
erosion controlExcellent
weed suppression potentialExcellent
green manure/cover crop useExcellent
spreading capabilityGood
N contribition potentialGood
DM potentialFair
Forage qualityGood
harvest time frame (late/early/year round)Early
number of harvest/yrUp to 2/yr
other commentsBest reseeding ability of the true clovers due to an ability to place seedhead into soil and large seed size; excellent heavily stocked, grazed pastures
Tolerance
bloat riskModerate
disease susceptibilityExcellent
insect/nematode ristkExcellent
cold toleranceFair
traffic toleranceGood
heat toleranceExcellent
drought toleranceExcellent
shade toleranceFair
dry soil toleranceGood
wet soil toleranceGood
pH rangeOptimum pH range is 5.8-6.5
required fertility (P,K, other nutrients)Tolerant of lower pH soils than most clovers; responds to P and K fertilization