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Post Date:
2nd Sep 2023
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Catch Crops, Cover Crops, or Green Manures are essentially the same and all fundamental in any organic growing set-up. They may not produce food directly but should be included in your crop program. GrowMad investigates.
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What are Catch and Cover Crops and why you should be using them
| Introduction
Catch and cover crops for the home gardener are more usually referred to as green Manure.
Whatever you want to call these invaluable crops, they are all essentially grown with similar objectives.
If your fruit and vegetable growing systems are organically based, then using these types of cropping will be an absolute necessity to gaining the highest yields possible.
Whether you garden organically or not, catch and cover cropping should be something you should be considering. It may on the surface seem a pointless exercise, but never judge a book by its cover.
Read more to discover why...
| What are Catch & Cover Crops
Catch, cover or green manures are all grown for pretty much the same reason - to protect and improve the soil between 'cash crops' or in the case of the home gardener, fruit and vegetable crops grown for the kitchen.
Cover crops are grown between the harvest and establishment of main (cash) crops. In general, they are sown during the autumn and over-wintered to be incorporated into the soil the following spring.
Catch crops are similar to cover crops but refer to the fact that they are very short-term, usually only covering the soil for between 6-10 weeks before being incorporated. They are also intended to 'catch' the available nitrogen in the soil and prevent nutrient loss.
Green manure is a crop grown to improve nutrition for the following crop, through the addition of fresh biomass (organic matter) and nutrients to the soil that the plant has captured, either by nitrogen fixation or nutrient uptake.
Each type is interchangeable and has very subtle differences but for the remainder of this article, we shall refer to them simply as cover crops.
The growing of a cover crop involves the sowing of a particular species/variety or mixture of types suited to this method, with the purpose of growing the crop for a period of time rather than leaving the soil fallow.
The crop duration depends on a number of factors but can be from as little as 6 weeks to as much as 3 years.
Cover crops have been used in agriculture for thousands of years and played an important part in Chinese, Roman and Greek farming practices.
The use became more widespread and an essential part of food production during the agricultural revolution of the 18th century as poorer quality land was farmed more intensively.
It fell out of favour, however, soon after the Second World War, as man-made synthetic chemical feeds and fertilisers became more readily available.
As gardeners have become more conscious of what they are eating, they have in turn become more aware of what they are applying to the soil and cover cropping has once again become fashionable and back in vogue.
| Advantages and benefits of using cover crops.
The use of cover crops has many advantages with some individual species being grown for very select purposes, such as biofumigation.
The primary uses of cover crops would include:
To improve soil structure
On heavier soils, certain cover crop species can be used to penetrate and break up soil structure and to improve drainage. The roots assist in the creation of biopores in the soil, which can improve subsequent crop root growth.
The addition of cover crops to very light soils adds much-needed organic material which can be used for moisture retention and to feed soil micro-organisms.
Good soil structure will also assist cation exchange capacity and aggregate stability.
To help improve soil biology
When cover crop biomass is incorporated back into the soil, it increases soil organic matter (SOM).
Organic matter provides an essential food source and habitat for the soil biological community which undertakes various processes such as decomposition, organic compound release and nutrient mineralisation.
Nitrogen fixation
Biological Nitrogen Fixation (BNF) is the process whereby legumes can through a symbiotic relationship with soil bacteria known as rhizobia, take atmospheric nitrogen (N2) and convert it into a usable form of nitrogen for the host plant, in this case, ammonia (NH3).
Nitrogen fixation is dependent on suitable species and varieties and a mixture of types is recommended.
Temperature is also an important factor. The best soil temperature range for nitrogen fixation is between 7°C and 20°C.
The stored nitrogen is released into the soil after incorporation of the cover crop.
Nitrogen uptake and release
Cover crops can be utilised over the winter to uptake nitrogen from the soil to be re-released back into the soil in early spring. Quantities of nitrogen mineralised back into the soil will depend on species/variety and quantity of the resulting biomass.
Winter rainfall can wash away soil nitrates as soil particles do not hold onto this nutrient very well. This is bad for the environment as it allows nitrates into watercourses but, for you, the grower, reduced nitrate concentrations in the soil are not desirable once spring plantings begin.
Growing nitrogen-hungry cover crops is a good method for literally 'mopping up' and storing nitrogen within the chosen species during the winter.
The reduction of soil erosion and runoff
Very light soils in exposed areas can be liable to soil erosion and can literally blow away. The growing of a cover crop will help stabilise the soil and protect it from excessively drying out during the summer.
Soils on sloping land may be liable to runoff and leaching of nutrients, particularly phosphorus. In extreme cases, topsoils can be washed away.
As with soil erosion, the growing of a cover crop will significantly reduce runoff issues you may experience.
Weed suppression
Because cover crops grow quickly, they can stop weeds from growing and smother existing weed coverage. This is particularly useful on ground that may otherwise lay bare. Cover cropping can be literally treated as a natural weed suppression membrane. Weed is suppressed by competition for light, nutrients and water.
In some cases, the use of certain species/varieties may cause a reduction in weed growth by allelopathy. (see below)
To reduce nutrient loss/leaching
If soil is left fallow for long periods, rainfall will leach nitrogen and other nutrients out, especially on lighter soils.
In many situations reducing leaching is more important in maintaining soil fertility than fixing nitrogen. This is particularly true during the winter when legumes are slow to establish and fix little nitrogen.
Fast-growing species with a deep root system are best for preventing leaching. Mustard is very effective for this purpose and can be drilled in late September or even into October, depending on local conditions.
Pest and disease control
Cover crops using certain species can control some nematodes by up to 90%.
Nematode Control Specific varieties of oil radish control certain plant-parasitic nematodes. The roots secrete pheromones which lure the larvae from their cryptobiotic state in the cysts. Then once in the roots, the larvae are subsequently unable to develop to maturity and die.
For maximum nematode control, sowing rates should be increased to produce high biomass and close root proximity.
Also, areas of cover crops can provide a habitat for predators of some of our garden pests. For example, frogs and toads will benefit from the damp shade provided by cover crops and will find a ready food source from lurking slugs and snails.
Hoverflies will be attracted to certain species/varieties such as clover and will prey on any resident aphids.
Biofumigation
The natural decomposition of certain cover crops releases toxins into the soil which can act as biofumigants.
Brassicas, as an example, will release isothiocyanates/glucosinolate which is harmful to soil-borne pests and has been shown to control some species of nematodes.
This biofumigant activity is also useful in the suppressing of some soil-borne diseases.
Allelopathy
Cover crops that either exude allelopathic chemicals or produce residues that release allelochemicals that are phytotoxic to weeds can be used as an organic method of weed suppression and management.
Allelopathy is the ability of a plant to release into the soil or environment, substances that act as germination or growth inhibitors to other plants or organisms.
Allelochemicals include benzoxazinone, phenolic compounds and hydroxamic acids.
Biodiversity and Habitat Creation
The range of biodiversity and habitat creation will depend on the chosen species/varieties and the time of year the chosen crop is produced.
Winter crops will create cover and shelter, summer crops will benefit birds and pollinators.
Ensure that summer flowering covers do not set and drop seeds that may cause unwanted issues in follow-on crops.
Each one of these individual advantages will, in turn, not only be good for the environment but lead to growth enhancement and higher yields in follow-on crops.
It should be noted that the benefits of cover cropping may not be immediately noticeable in the follow-on crop but may take several repeated cycles depending on species/mixtures of varieties, to achieve the desired crop yield improvements.
| Disadvantages of Using Cover Crops
As discussed, cover crops have many advantages in their use however, as with all good things, there can be some negatives on the flipside.
Some of the drawbacks to using cover crops would include:
Initial cost with no immediate return
The cost of setting land aside for cover crops will cost money for seed and time to prepare seedbeds and establish the crop and it may take several crops or seasons before any real benefits are realised or noticeable.
Loss of a 'cash' crop
The fruit and veg that you produce are the whole reason for you getting dirt under your fingernails in the first place.
These crops or your 'cash crop' is what it's all about.
If your plot or allotment is covered with cover crops, as useful as they are, they are preventing you from growing harvests of your favourite winter crops.
You will need to plan carefully and balance the advantages of cover crops and losing growing areas.
Pest and disease 'green bridge'
Areas set aside for the production of cover crops, will in many cases be in place for the entire duration of the autumn and winter.
Unless you are growing a frost-sensitive species/variety, it will remain 'green' throughout this period and may act as a place of sanctuary for possible overwintering of certain pests and diseases.
This is known as the 'Green Bridge Effect' literally carrying pests and diseases from one season to another.
Potential increase in slug numbers
As with green bridging, carrying large areas of biomass over the winter can encourage points of sanctuary for a number of pests and diseases, in particular, slugs and snails.
Slugs and snails like nothing better than cover away from daylight that remains cool and wet. Cover crops can lead to a huge increase in their numbers over the autumn and winter. Be well prepared in the spring.
Getting the crop established late in the season
Cover crops make an excellent subject to grow over winter on what may have otherwise been fallow ground.
The ideal time for the establishment of the crop is late summer/early autumn but this may conflict with other crops still growing.
This may result in cover crops being sown well into October. October generally should give good germination but if the weather turns cold or there is a lack of moisture, germination and crop establishment may be poor or nonexistent.
Clubroot risk with brassicas
Clubroot in brassicas can be a real problem.
Once you have this disease in your soil, it is incredibly difficult to eradicate and can only be combated by using clubroot-resistant varieties.
To avoid potential issues, always practise good hygiene and correct rotation after growing brassica-related cover crops.
Poor frost tolerance in some species/varieties
Some species/varieties (Buckwheat is a good example) are not frost tolerant and will only be suited to growing during warmer or milder months of the year.
Consider why you are growing a cover crop and what eventual outcome you are looking for eg. nitrogen fixation, organic matter improvement etc and choose a suitable species/variety for the planned time of year.
Rotational conflict
Crop rotation is an essential part of any cropping program, organic or conventional.
Many cover crops are members of either the legume or brassica families. As with any cropping rotation, legumes should never precede or follow legumes. The same applies to brassicas.
Your cropping plans/schedules should take these possible rotational issues into consideration.
Potential allelopathic issues
Allelopathy is the ability of a plant to release into the soil or environment, substances that act as germination or growth inhibitors to other plants or organisms.
Check that any cover crop you plan on using won't leave any traces of unwanted inhibitors in the soil for your follow-on crops.
Increased weed pressure
An area of soil covered in any crop will inevitably have competition from weeds.
Try and get cover crops incorporated back into the soil if weed starts to take control before it has time to drop seed.
Additional workload at an already busy time of year
The ideal time of year for successfully establishing a cover crop is late summer.
This can be an incredibly busy time during the growing season when your resources of time and money may be stretched.
You may find it difficult to allocate the necessary resources to establish a cover crop to its maximum potential. Planning ahead is key.
| Types, Species and Varieties of cover crop
Cover crops fall into 3 main categories: Legumes, Grasses/Cereals and Brassicas. Each of these categories is then subdivided into species and varieties (where applicable).
There is a fourth category that includes Buckwheat, Linseed, Chicory and Phacelia which are all essential cover crop subjects, but don't fit a specific group.
| Legumes
Legumes make an excellent choice for cover cropping as they are all capable of nitrogen fixation and contribute to the improvement of soil structure.
For maximum potential, legumes generally require earlier sowing dates and may remain for longer periods in production.
Careful consideration will be needed if follow-on crops are likely to be legumes or pulses.
Key Species/Varieties:
Crimson Clover (Trifolium incarnatum) 
A short-term annual, grown to provide a quick boost to soil fertility. The seed should be broadcast at a maximum depth of 10mm and rolled to ensure good contact with the soil. Sowings should be made between March and May at the latest as summer sowings may struggle to establish. Later sowings can be made during late August. Generally pest and disease-free.
- Average Nitrogen fixer
- Frost tolerant
- Good weed suppressor
- Minimum pest and disease issues
- Produces a mass of red flowers when mature
Persian Clover (Trifolium resupinatum) 
A short-term annual, grown to provide a quick boost to soil fertility. The seed should be broadcast at a maximum depth of 10mm and rolled to ensure good contact with the soil. Sowings should be made between March and May at the latest as summer sowings may struggle to establish. Later sowings can be made during late August. Generally pest and disease-free. Not frost tolerant but this species will regenerate if hit by frost.
- Average Nitrogen fixer
- Good weed suppressor
Red Clover (Trifolium pratense) 
An incredibly popular cover crop, particularly in organic setups. A mid to long-term prospect crop suited to adding to soil fertility as well as being a good nitrogen fixer. The seed should be broadcast at a maximum depth of 10mm and rolled to ensure good contact with the soil. Sowings should be made between March and May at the latest as summer sowings may struggle to establish. Later sowings can be made during late August. Foliage dies down in winter but regenerates during the following spring.
- Widely grown
- Very good nitrogen fixation (increases with mowing)
- Competes well with weeds
- More susceptible to soil-borne diseases than other clovers
Sweet Clover (Melilotus officianalis) 
A tall biennial white or yellow-flowered clover produces very large quantities of biomass. The seed should be broadcast at a maximum depth of 10mm and rolled to ensure good contact with the soil. Sowings should be made between March and May at the latest as summer sowings may struggle to establish. Later sowings can be made during late August. This cover crop is capable of high nitrogen fixation but does not compete well with weeds. As a biennial, it will die down during the winter but having a large tap root, will reemerge the following spring. This clover is more susceptible to downy mildew than other clover types.
- Frost tolerant
- Very good nitrogen fixation potential
- Does not compete well with weeds
White Clover (Trifolium repens) 
A widely used cover crop for nitrogen fixation and grazing of livestock. The seed should be broadcast at a maximum depth of 10mm and rolled to ensure good contact with the soil. Sowings should be made between March and May at the latest as summer sowings may struggle to establish. Later sowings can be made during late August. White clover is considered a long-term crop of up to 7-8 years and can be persistent in follow-on crops.
- A very long-term crop
- Good nitrogen fixation potential
- Frost tolerant
- Pest and disease-free
Fenugreek (Trigonella foenum-graecum) 
Useful to fill short breaks in cropping as Fenugreek is very quick to establish. Sown between March and May, this species quickly suppresses weeds and is useful for improving soil fertility in a short space of time.
- Very quick to mature
- Good weed suppressor
- Limited nitrogen fixation because of its short life cycle
- Average frost tolerance
Lucerne/Alfalfa (Medicago sativa) 
A long-term crop with good nitrogen-fixing potential. Although slow to establish, Lucerne/Alfalfa makes an excellent choice of cover crop and doubles up as superb forage for livestock. It is suited to spring and summer sowings with the optimum time during May. Late summer sowings can be made in August. Although fairly pest and disease-free, Lucerne/Alfalfa can be susceptible to downy mildew, verticillium wilt and stem nematode.
- A long-term crop
- Good nitrogen fixation potential
- Frost hardy but dies down in winter
- Does not suit acidic soil conditions
- Drought tolerant
Sainfoin (Onobrychis viciifolia) 
This perennial cover crop is highly suited to growing on limestone and chalky soils. It has a large seed that should be sown during spring at a depth of 20mm and rolled to ensure good contact with the soil. It offers average nitrogen fixation but makes excellent forage for livestock. Has few issues with pests and diseases but can be susceptible to crown rot.
- A long-term crop
- Average nitrogen fixation potential
- Very frost tolerant
- Good forage for livestock
Vetch (Vicia sativa) 
Vetch, also known as winter tares, is widely used as a nitrogen fixer and is very well suited for weed suppression. It has a larger seed than clover and should be sown during spring at a depth of 20mm and rolled to ensure good contact with the soil. Winter varieties are available.
- Good nitrogen fixation potential
- Very good weed suppressor
- Good frost tolerance
- Short-lived annual
Yellow Trefoil/Black Medick (Medicago lupulina) 
A short-lived annual or biennial commonly used for undersowing of other crops, such as maize. Yellow trefoil has a very small seed and should be shallowly sown in the spring and rolled to ensure good contact with the soil. Biennial crops should be sown during mid-late August.
- Average nitrogen fixation
- Good weed suppressor
- Frost tolerant
- Pest and disease-free
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Grasses & Cereals
Grasses and cereals can establish very quickly and offer good ground coverage which is useful against soil erosion and helpful in controlling weed populations.
Grasses and Cereals also offer a much larger range of potential sowing dates than legumes or brassicas.
Key Species/Varieties:
Black Oat (Avena strigosa)
Black oat is a useful crop to assist with soil compaction as it has an advanced root system. It is also more tolerant of frost than some of the other cereal cover crops. It should be sown from August to October at a depth of 1-2cm and should be considered a long-term crop.
- A good cover crop for compacted soils
- Possible allelopathic issues
- Frost tolerant
- Controls some nematodes
Cocksfoot (Dactylis glomerta)
A dominant and very frost-hardy grass, Cocksfoot is useful as a weed suppressor and for holding nitrogen. It should be sown at a depth of 1cm between March and May or August and October Pest and disease resistant.
- A good weed suppressor particularly if mixed with clover
- Very frost tolerant
- Can be used for short or long-term crops
- Requires regular mowing
Grazing/Forage Rye (Secale cereal) 
Quick to establish and very frost tolerant, grazing rye is one of the best grasses for holding nitrogen and for suppression of weeds. Generally treated as a short-term crop, it should be sown during late summer at a depth of 1cm and incorporated the following spring. It can have an allelopathic effect on follow on crops and a period of at least 6 weeks should elapse before drilling follow on crops.
- Quick to establish
- Possible allelopathic issues
- Very frost tolerant
- Competes well with weeds
Italian Ryegrass (Lolium multiflorum) 
This is a short-lived grass lasting for two years. It is very high-yielding and reliable.
Italian ryegrass can be spring sown but performs better from late summer sowing.
- Super fast germination, establishment and early spring growth
- Will grow in lower soil conditions than other grasses
Perennial Ryegrass (Lolium perenne) 
Perennial ryegrass thrives on a wide range of soil types and is easy to grow.
Perennial ryegrass is a productive grass of medium height. In good fertile growing conditions, it is capable of fast growth, producing a large bulk of smooth flat green leaves with glossy undersides. It is by far the most used and economically important grass in the UK.
- Quick to germinate and long-lived
- Grows well in any soil type
Westerwolds Ryegrass (Lolium westerwoldicum) 
Westerwolds is capable of extremely fast growth. Westerwolds ryegrass is one of the most effective crops for reducing nitrogen leaching over the winter. It is a very good N Lifter and is very quick to make a large root mass making it suitable as a green manure. It effectively seeks out and mops up nitrate in the soil.
- Super fast germination, establishment and early spring growth
- Annual grass that lasts 1-2 years
- Extremely fast-growing and establishment
- Will grow in lower soil conditions than other grasses
- Nitrogen Lifter
- Good weed suppressor
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Brassicas
There are several types of brassicas suited to cover cropping including mustards, radishes and turnips.
Brassicas are easy to establish and are often sown in late summer or early autumn for over-wintering. Being deep-rooted, they make excellent subjects for penetrating compacted soils and improving soil structure.
Considerations will be needed regarding the use of brassicas in the crop rotation for potential conflicts eg. clubroot.
Key Species/Varieties:
White Mustard (Sinapsis alba) 
White mustard is a short-term crop and particularly useful if you are overwhelmed with soil-borne diseases as this plant has useful biofumigation properties. Sow shallowly from March onwards and roll to ensure good contact with the soil. White mustard is easily established, very quick growing and has very good weed suppression possibilities. Mustards do not fix nitrogen but stop it from leaching from the soil. This crop is not frost-hardy and suffers from all of the similar pests and diseases associated with other brassica species.
- Not frost tolerant
- Very quick growing
- Useful biofumigation potential
- Good weed suppressor
Brown Mustard (Brassica juncea) 
Brown mustard has all of the qualities of white mustard but has the added benefit of being winter hardy if a longer-term mustard crop is required. Sow shallowly from March onwards and roll to ensure good contact with the soil.
- Frost tolerant
- Very quick growing
- Good weed suppressor
- Useful biofumigation potential
Ethiopian Mustard (Brassica carinata) 
A mustard species suited to poorer soils but benefiting from all other qualities of other types of mustard. It produces a very leafy canopy so is particularly suited to weed suppression. Sow shallowly from March onwards and roll to ensure good contact with the soil.
- Works well on poorer soils
- Frost tolerant
- Very good weed suppressor
Oil Radish (Raphanus sativus) 
Oil radish is grown for its ability to scavenge and lock up nitrogen. It is very quick to establish and late to mature, with good weed suppression potential. It also has exceptional nematode control action. It should be sown between April and September and is frost tolerant but not winter hardy.
- Quick to establish
- Good weed suppressor
- Useful for locking up nitrogen
- Good nematode control
Tillage Radish (Raphanus sativus) 
Tillage radish varieties have similar qualities to oil radish but the key difference is root size. A tillage radish has a much larger root system that is capable of penetrating compacted soils far better than standard varieties. This improves drainage and ultimately soil structure. It should be sown between April and September and is frost tolerant but not winter hardy.
- Exceptional root penetrating qualities
- Quick to establish
- Good weed suppressor
- Useful for locking up nitrogen
- Good nematode control
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Other Types
Buckwheat (Fagopyrum esculentum) 
A very popular but short-lived cover crop, particularly in organic setups. It does not fix nitrogen but does stop it from leaching, its main use is for weed suppression and because it's useful for searching out phosphate in the soil that can be returned after incorporation to be utilised by follow-on crops. Sowing should be carried out during April or May. Buckwheat is generally pest and disease-free.
- Not frost tolerant
- Good weed suppressor
- Good for scavenging for phosphates
Chicory (Cichorium intybus) 
Chicory is used as a 'pan buster' as its taproot is capable of penetrating the most compact of soils. Sowing should be in the spring or late summer at a depth of 10mm and rolled to ensure good contact with the soil. This crop does not fix nitrogen but once established, gives good weed suppression. Chicory is generally pest and disease-free.
- A long-term crop (up to 10 years)
- Excellent 'pan busting' capabilities
- Good weed suppression once established
- Frost tolerant
Linseed (Linum usitatissimum) 
Linseed or Flax makes a good cover crop for dry soils that also lack good structure. It also has good weed suppression qualities but is sensitive to frost, so early sowing is not recommended. Sow from May onwards and roll to ensure good contact with the soil. Generally pest and disease-free.
- Not frost tolerant
- Germinates and establishes on dry soils
- Good weed suppression
Phacelia (Phacelia tanacetifolia) 
Phacelia is not a nitrogen fixer but a good holder of it over the summer period. Phacelia is quick to establish and its strengths lie in its ability to attract bees and hoverflies as well as good weed suppression. Sow shallowly from March onwards and roll to ensure good contact with the soil. This crop is generally pest and disease-free.
- Very good at attracting bees and hoverflies
- Good weed suppressor
- Not frost tolerant
- Useful for holding nitrogen
| How to sow and establish a cover crop
Time of year
Sowing and establishing your cover crops is an essential task that will need to be mastered for the best results.
Establish cover crops and green manure as soon as possible after the previous cash crop.
Sowing dates are reasonably flexible and will be determined by clear ground availability and the needs of individual types and varieties.
Some cover crops can be inter-sown into existing crops that are already growing but in general, sow cover crops as soon as the soil is available.
Ideally, cover crops should be sown during late summer with sowings completed by mid/late September. Some types/varieties will suit earlier sowings (May/June) such as legumes, whilst some can be held off until later in the autumn. Follow your seed supplier's individual guidelines for each choice of cover crop.
Late sowings run the gauntlet of poor germination and struggling to establish and put on sufficient growth before the onset of winter.
Exploit favourable conditions and sow when the weather is warm and the soil moist, just before predicted rain would be perfect. This will assist in quick germination and early establishment.
Sowing and Growing
All soils are suitable for growing cover crops, but having a pH level above 5.6 is preferable.
Broadcast seed rather than sowing into individual drills. Don't be shy with seed rates, sow liberally to ensure good coverage and to allow for non-germinating seeds.
If possible, after sowing compact soil slightly as good seed-to-soil contact is required for germination and emergence. This will also help to retain moisture and assist in deterring slugs and snails. Do not over-compact.
Allow crops to grow but ensure they are incorporated before they come into flower. Late incorporation and seed development may result in your cover crops becoming more of a weed in the following season than a beneficial crop.
Incorporation
For cover crops to be beneficial to your soil, they will need to be buried into the soil, a process known as incorporation.
Summer crops can be ready for incorporation after 8-10 weeks, with some autumn-sown crops being carried over the winter and terminated in the spring.
Destroy cover crops at least 3 weeks before establishing a new seed bed.
Cover crops are usually killed off before soil preparation for the next crop. Methods of destruction vary but mowing or strimming with a brush cutter work well.
Cover crops that are not winter-hardy or frost-tolerant will be naturally killed off by winter weather.
The interaction of sowing date, soil type and cover crop growth (canopy size and type of growth) will determine the best method of destruction.
The timing of cover crop destruction will determine soil temperature, soil moisture, nutrient cycling and levels of toxic chemical compounds associated with some cover crop species.
However, there are several advantages of destroying a cover crop relatively early:
- Increases soil-warming rate which can speed up germination and establishment
- Can reduce potential phytotoxic effects of residues on the following crop
- Reduces disease inoculum survival rate
- Speeds up crop residue decomposition
- Decreases interference with future seed sowings and crop planting
- Cover crop biomass can act as a blanket and reduce the natural drying process, particularly on heavier soils
| Recommended Seed Suppliers
The Organic Gardening Catalogue
Alternatively, you may find other choices of cover and catch crop seed from other suppliers in The GrowMad Seed Directory.
| Useful Links
| Conclusion & Takeaway
There is clear and growing evidence that cover crops have considerable potential to improve the health and vitality of soils in intensive vegetable rotations.
The choice of species or mixture and the most appropriate techniques for using a cover crop will differ depending on the soil type, growing system, climate and length of the growing season, but any cover crop is better than none at all.
The important consideration is to try and have something growing in the soil at all times, if not a cash crop, then a cover crop.
If the soil is clear for 2 months or more, sow cover, and if you need a quick crop, phacelia should be the go-to subject. It's fast germinating, quick growing and trouble-free. Considerable coverage can be obtained in less than 2 months in ideal conditions and works well until early winter.
Always have something growing in your soil.
