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Vegetables

Fruit and vegetables are probably the most common organic produce available. However, a large proportion of them is imported, particularly during the winter, suggesting considerable scope for home production.
It is also true that consumers prefer local produce, but it is often difficult to obtain.
Organic vegetable production is relatively intensive compared with many other organic enterprises, and particular care is required in devising a practical and financially successful production system.
There are three main ways in which organic vegetable production can be implemented:
  • As field crops within a rotation on an organic farm alongside other organic enterprises
  • As a market garden enterprise within a rotation on an organic farm with other organic enterprises
  • As a stand-alone market garden
In any of these situations protected cropping under polythene tunnels is an additional option.

Challenges in organic vegetable production

There are four main challenges to growing organic vegetables:
  • Building and maintaining soil fertility
  • Weed control
  • Maximising the production season
Careful planning is required to develop practical systems and optimise returns.
A realistic assessment of the labour and time resources needed, and available, must also be taken into account during planning.
There will probably also be a need for finance for specialist equipment.

Soil fertility and management

Building and maintaining soil fertility are high priority and organic standards require that vegetable holdings should aim to be largely self-sufficient in providing crop nutrients from home-produced manures, composts and green manures.

Rotations

Apart from being part of the weed, pest and disease prevention regime, carefully planned vegetable rotations are essential for exploiting soil nutrients at different depths and for balancing nutrient use with replenishment.
In a market garden situation, a significant proportion of green manures (25-50 percent) should be included within the rotation.
Longer rotations are preferable to shorter ones, and their design is often made easier by the inclusion of significant periods under nutrient building legume green manures.
Market garden rotations will also need to take into account the need for year-round production.

Green manures

Green manures are crops grown specifically for building and maintaining soil fertility and structure. They are incorporated back into the soil, either directly or after removal and composting.
There are restrictions on sources of brought-in manure, particularly concerned with maintaining freedom from Genetically Modified Organisms (GMOs). It is imperative that vegetable producers, particularly in market-gardens, make maximum use of green manures for providing nutrients and organic matter, and as a major part of the weed control programme.
Green manures include legumes for nitrogen generation, short-term green manures as cover crops, green manure mulches and over-wintering green manures.
In practice this means that within the cropping rotation green manures should effectively account for:
  • at least ¼ of the rotation when supplemented with manures;
  • ⅓ to ½  of the rotation when manures are not available.

Manures

If the vegetable unit is part of a larger organic farm, there may be organic manure available for growing vegetables. Alternatively organic poultry manure could be considered. It must be well composted and incorporated into the soil and not used as a mulch in order to avoid contamination of produce.
At present, some non-organic manure may be brought in to supplement on-farm resources, but the source and quantity require clear prior approval from your certification body. Of specific importance will be ensuring, and proving, that the animals that produced the manure have not been fed any GMO feed.
A high reliance on brought-in manure is not allowed, nor are manures from intensive livestock farms. Brought-in manure will also require composting for several months prior to use.

Weed control

Since there are no herbicides available to organic growers, weed control can cause major worries for organic vegetable producers.
Weed control can be effected by a combination of:
  • Correct choice of beds, ridges or drills to suit the crops grown
  • Proper rotational practices
  • Extensive, planned use of green manures and cover crops
  • Stale seedbed techniques
  • Sowing and planting dates targeted to minimise competition from weeds
  • Mechanical cultivations and hand weeding, including hoeing
  • Specialist weeding equipment - eg steerage hoes, brush and flame weeders
  • Organic matter-based and plastic-type mulches
It is vital that provision/capital for equipment and/or labour requirements is included in plans for producing organic vegetables.
Specialist weeding equipment does exist and, as it can be expensive, sharing of equipment can reduce costs.

Pest control

Important means of pest control include:
  • Proper planned rotations
  • Preventing build up of weeds as hosts or shelter for pests
  • Provision of suitable habitats for pest predators
  • Companion plants - plants which attract a pest’s predators or directly repel pests
  • Barriers that deny pests access to crops
Very few pesticides are available (under strict derogation) to organic growers, but an increasing range of biological control agents is being developed, mostly for use in polythene tunnels.

Disease control

Disease control is based on provision of a soil and environment that produce strong, vigorous plants and which discourage disease.
Disease control measures include:
  • Proper rotations and growing of resistant varieties
  • Biological diversity and companion planting to avoid mono-cropping
  • Good field hygiene
These are supplemented by a small number of permitted fungicides (under derogation).

Maximising the production season

Many organic vegetable producers initially concentrate on summer vegetable crops. This is the easiest option, but does mean that customers cannot be supplied during the winter months, except by importing produce from elsewhere.
Growers therefore need to develop systems for producing crops all year round, both in the field and under protection in order to maintain continuity of supply and to retain customers.
In addition, there may be a need for storage facilities, possibly shared by several producers.

Protected cropping

Polythene tunnels are common on many organic vegetable holdings since they allow production and hence income throughout the year. They are used for:
  • Summer salads and tender vegetables
  • Extending the growing season both in the spring and autumn/early winter
  • Winter cropping
  • Plant propagation
Basic organic production principles and rotational practices are similar to field grown crops.

Soft fruit

Soft fruit such as strawberries, gooseberries, raspberries and currants are increasingly popular on organic horticultural holdings. Production methods are continually improving as more producers come on stream, though some problems, such as gooseberry sawfly control, still require to be overcome.
Supplies of organic plants are poor, requiring conversion of conventional plants.
An additional difficulty with soft fruit is obtaining pickers at harvest time.

Top fruit

Top fruit production, mainly apples and pears, is at an early stage of development in the UK, and limited firm information is available.
What is known is that:
  • Choice of variety is very important
  • Many non-organic varieties widely sold in shops are not easy to grow organically
  • Disease resistance is important with apple scab and canker being  problematical

Seeds and other planting material

Vegetable seed, transplants and vegetatively propagated materials such as fruit bushes and trees, seed potatoes, onion setts and strawberry runners must normally be obtained from a registered organic source.
Derogations for the planting of untreated, nonorganic material can sometimes be obtained when suitable organic material is not available. Prior permission must be sought from your certification body, and sound reasons must be presented.
Organic vegetable transplants are difficult to obtain in Northern Ireland, though a few specialist growers may grow them under contract. Many growers produce their own from seed.

Marketing

There are many ways of marketing organic vegetables, and existing organic producers employ various methods to suit their scale of operation including:
  • Farm shops and farmers’ markets
  • Box delivery schemes
  • Supplying wholesalers or multiple retailers
  • Supplying restaurants and the general retail trade
The best returns are generally from direct marketing through farm shops, box schemes and markets, provided that overhead costs such as delivery can be kept down.
Home-produce marketed through farm shops and box schemes is frequently supplemented by imported produce, particularly during the winter months.

Producer groups

The time and labour overheads associated with marketing and distribution are encouraging many vegetable producers to consider forming producer groups to:
  • Market and distribute jointly under a single ‘brand name’
  • Produce jointly to planned agreements
  • Share equipment and facilities

Other horticultural produce

Vegetable producers have found that producing other types of organic horticultural produce supplements the vegetable production. Options include herbs, cut flowers, bedding plants, nursery stock and trees.
There are very specific standards for selling growing plants.

Further information

For more information see other leaflets in this series:
  • Green Manures
  • Polytunnel cropping
  • Starting an organic market garden

Contacts for further information

Adrian Saunders
Greenmount Campus, ANTRIM, BT41 4PU
Tel: (028) 9442 6765
Mobile: 07887 708807
E-mail:adrian.saunders@dardni.gov.uk
April 2008