What Is a Cover Crop?
A cover crop is a plant species grown primarily to benefit the soil rather than for harvest. These crops are usually planted in the off-season or between cash crops and are terminated before they reach full maturity. Their main purposes include:
- Enhancing soil structure
- Preventing erosion
- Fixing nitrogen
- Suppressing weeds
- Supporting beneficial insects and pollinators
Using cover crops is a proven strategy in regenerative and conservation agriculture.
Main Types of Cover Crop Species
Cover crops are generally grouped into four categories: legumes, grasses, brassicas, and others. Each type offers unique benefits depending on your goals—whether you’re improving nitrogen levels, breaking up compacted soils, or reducing pest pressure.
- Legume Cover Crops
Legumes are prized for their ability to fix nitrogen in the soil through a symbiotic relationship with rhizobia bacteria. This makes them ideal for restoring fertility naturally and reducing the need for synthetic fertilisers.
Popular legume species in the UK include:
- Crimson Clover (Trifolium incarnatum): A quick-growing annual with striking red flowers; attracts pollinators and fixes nitrogen.
- Winter Vetch / Hairy Vetch (Vicia villosa): Hardy, slow to establish but highly effective at nitrogen fixation.
- Field Beans (Vicia faba): Commonly used in winter mixes; great biomass and nitrogen contribution.
- Lucerne / Alfalfa (Medicago sativa): A deep-rooted perennial ideal for breaking up heavy soils and improving drought resilience.
Best used for:
- Nitrogen enrichment
- Soil fertility
- Attracting beneficial insects
- Grass Cover Crops
Grasses are known for their fibrous root systems, which help prevent erosion, improve soil structure, and build organic matter. They grow quickly and produce large amounts of biomass.
Popular grass species:
- Ryegrass (Lolium multiflorum or perenne): A fast-growing option ideal for weed suppression and erosion control.
- Cereal Rye (Secale cereale): Excellent winter cover, especially for erosion-prone soils.
- Oats (Avena sativa): Easy to establish, great for fallow periods and improving soil tilth.
Best used for:
- Weed suppression
- Erosion control
- Organic matter build-up
- Brassica Cover Crops
Brassicas include species from the mustard and cabbage family. They are fast-growing and known for deep taproots, which can break up compacted soils and scavenge nutrients from deeper layers.
Common brassica species:
- Oilseed Radish (Raphanus sativus): Excellent for bio-drilling and reducing soil compaction.
- Mustard (Sinapis alba or Brassica juncea): Known for rapid growth and potential biofumigant properties.
- Turnips and Forage Rape: Often used in grazing systems and for soil improvement.
Best used for:
- Breaking up compacted soils
- Pest and disease suppression
- Grazing or forage
- Other & Multi-Species Cover Crops
Some plants don’t fall neatly into the main categories but still offer excellent cover crop benefits. Many farmers now use multi-species cover crop mixes to maximise soil health through plant diversity.
Examples include:
- Phacelia (Phacelia tanacetifolia): Attractive to pollinators and beneficial insects, with fine roots for improving soil texture.
- Buckwheat (Fagopyrum esculentum): A fast-growing summer annual that suppresses weeds and attracts pollinators.
- Sunflowers, Chicory, Sainfoin: Great in mixes for deep rooting and biodiversity.
Best used for:
- Pollinator habitat
- Soil conditioning
- Supporting natural pest control
How to Choose the Right Cover Crop
When choosing a cover crop species, consider:
- Your climate and planting window (e.g. winter-hardy vs summer annual)
- Soil needs (e.g. compaction, low nitrogen, erosion)
- End use (e.g. grazing, green manure, weed control)
- Crop rotation plans (avoid species related to cash crops to prevent pest buildup)
For most UK growers, a mix of species often delivers the best results, balancing soil structure, fertility, and biodiversity benefits.
Frequently Asked Questions (FAQs)
Q: Can cover crops be used in home gardens?
Yes! Cover crops like clover, oats, and mustard are excellent choices for small plots and allotments to improve soil between growing seasons.
Q: Do cover crops need fertiliser?
Usually, no. Especially legumes, which fix their own nitrogen. However, some crops may benefit from a starter fertiliser depending on your soil condition.
Q: When should I terminate my cover crop?
Most are cut, grazed, or tilled in before flowering or seed set to avoid reseeding and to maximise nutrient availability.
Q: Can I graze livestock on cover crops?
Absolutely. Many cover crops are suitable for grazing—just ensure the species is non-toxic and the field has proper rotation to avoid overgrazing.
Q: Are cover crops suitable for organic farms?
Yes, they’re widely used in organic systems as a natural way to build soil health and reduce chemical inputs.
Final Thoughts
Incorporating cover crops into your land management strategy is one of the smartest moves you can make for long-term soil health and productivity. Whether you’re aiming to fix nitrogen, suppress weeds, or simply give your soil a seasonal rest, there’s a cover crop species (or mix!) suited to your needs.
Interested in creating a custom cover crop mix for your field or garden? Let us know your goals and we’ll help you build a plan that works for your farm.
