GREENER FINGERS - Sustainable Gardening


We all have a moral duty to behave in sustainable way across all aspects of our lives.

Growing our own food provides many opportunities in this respect. For example, our plots provide diverse habitats for wildlife (particularly insects) which can be further enhanced by restricting our use of chemical pesticides. By generating our own compost and using local sources of manure we can reduce our reliance on man-made fertilisers. These, and similar practices lead to healthier soils on allotment sites than those found on farmland with modern commercial agricultural processes;

The following sections describes ways in which you can grow crops without harming the environment and, in many instances, making a positive contribution to it.

People think about having an allotment for different reasons and a key issue is enjoying the process of growing while enabling my family to eat vegetables that were free of chemicals. 

There is a lot of research now to suggest that the overuse of chemicals in farming generally is not good for human health and is also having an effect on wildlife. The organic method places importance on looking after your soil. Growing plants takes nutrients out of the soil and you will need to replace these regularly.


Green manure

Organic gardening uses techniques which occur naturally – the word ’organic’ describes living organisms. 

 People think about having an allotment for different reasons and a key issue is enjoying the process of growing while enabling my family to eat vegetables that were free of chemicals. 

There is a lot of research now to suggest that the overuse of chemicals in farming generally is not good for human health and is also having an effect on wildlife. The organic method places importance on looking after your soil. Growing plants takes nutrients out of the soil and you will need to replace these regularly.

Some people think that organically grown food tastes better but the proven benefits are safer growing (by using fewer potentially toxic pesticides and fertilisers) and protecting/encouraging wildlife. It can also reduce waste where compost is used by recycling kitchen and/or gardening waste. 

Organic gardening includes the following: 

  • Using natural mulches to restrict weed growth and retain soil moisture 
  • Using organic manures and peat-free compost 
  • Capturing and storing rainwater 
  • Cultivation processes with reduced or no digging 
  • Plant to encourage beneficial predators: birds, insects (ladybirds, wasps, lacewings…) and reptiles (frogs, toads and slow worms) 
  • Companion planting – plants which benefit each other (e.g. the onion family can be grown with carrots to deter carrot fly) 
  • Using green manure over winter to keep the soil warm and retain moisture 

It is not easy to be wholly organic but applying some of the principles will help to establish a natural balance on your plot. 

For more information see 

The 'No Dig' Method

Soil is a living mixture of diverse organisms and works better when it’s not disrupted. No-dig gardening can bring many benefits to your plot and is gentler on your back than traditional methods of growing vegetables. Nutrient rich materials – compost, manure, etc. – are applied at normal rates but only at the surface of the soil. Worms and other organisms do the work of bringing the nutrients into the ground.

The basic requirements are:

  • Avoid treading on areas where plants will be grown – this generally requires beds to be no wider than 1.2m (4’)
  • Regularly apply organic matter – well rotted horse manure, spent mushroom compost or maybe garden compost - over the ground surface to a depth of about three inches compost, manure and mulches
  • Apply nutrient rich fertilisers in the spring when plants are growing at their fastest and the weather is less likely to wash them away
  • Gently ruffle the surface when preparing seed beds
  • When beginning beds, apply opaque coverings (cardboard, carpets or sheeting) to kill of any weeds 
  • Beds that can be reached easily from both sides, avoiding the need to tread on growing areas
  • Regularly hoe out any weeds, and Hoe in – rather than dig over – any green manures

Earthworms, bacteria and fungi, all of which contribute to healthy soil, can be adversely affected by disturbance such as digging and by compacting soil. Most soil life is closest to the surface, and digging can bring poorer quality soil to the surface. Digging can also help seeds from weeds to find ideal conditions for growth.


Mulch Ado...


A good way to replace nutrients without chemical fertilisers is to spread organic material such as well rotted horse manure, spent mushroom compost or maybe garden compost over the ground surface.

Mulch is the name given to this  thick layer of organic matter which absorbs rainfall, reduces evaporation and keeps the soil warm. Ideally it should be at least 10cm (4”) thick, but as this would dwarf small seedlings it can be applied in layers. 


The first layer should be overlapping card or newspaper applied around any established plants. This layer’s job us to block out light and suppress weeds. Weed control fabric could be applied as an alternative.

This layer is then covered with plant matter to keep it in place: grass cuttings, leaves, compost, wood chip, straw and small non-pernicious weeds (without seeds) are all ideal. This is the layer which is most effective at moderating the temperature and moisture content of the soil  

The deeper the layers the better but you should aim to cover the soil to a depth of about three inches. More good news is that you don’t have to dig in the organic matter into your ground. All you do is sit back and allow worms to take the material down into the soil and for all the beneficial bacteria present to process it so it can be absorbed by whatever plants you are going to grow. 

The other benefit of applying a mulch is that the soil structure is much improved, opening up the ground to the penetration of water and making it much easier to plant things into it. You could aim to apply a mulch as often as possible even when you have plants growing but in any event you should do it at least once a year either after the growing season has ended, around the end of October, or perhaps in early spring.  



Good compost is invaluable. 

Compost introduces nutrients to support plant growth. It lightens heavy soils, helps soils to retain moisture, and helps control plant diseases. 

Compost falls into two broad categories: garden compost and potting compost.

Garden Compost

Garden compost refers to the material that we can all produce when we gather kitchen and garden waste and leave it to decompose. Home-made compost ideally contains equal amounts of green materials (grass cuttings, fruit and vegetable peelings, young plants, animal manure, etc. which have a high nitrogen content) and brown materials (leaves, straw/hay, woody shoots, cardboard and paper). 

As the vegetable matter rots it generates heat. The heat accelerates the decomposition process resulting in rich, dark organic matter that can be dug into the soil or applied as a mulch. Adding materials such as nettles, comfrey and urine to compost can also help to accelerate the process. Oxygen is a key element in the decomposition process and garden compost should be periodically turned with a fork to introduce air.

Making compost helps the environment: reducing numbers of bonfires, cutting down on waste, and reducing demand for manufactured products. It can also provide a habitat for hedgehogs, beetles and slow-worms, many of which feed on slugs act as natural pest controllers, reducing the need for chemical pesticides.

Potting Compost

Potting compost is the bagged material that we get from garden centres (and The Shed!). Bagged compost is available in several forms to serve specific purpose – multi-purpose compost can be used at all stages in the growing cycle, seed compost is designed to assist germination, ericaceous compost is designed for plants which prefer acid soils, tomatoes and strawberries are planted directly in grow bags. Peat free compost is widely recognised as being more environmentally sustainable than those containing peat.


Plant Diversity


Growing many different types of plant close together creates several small natural ecosystems which, in turn, creates habitats for a wide range of creatures. This increases the chances of encouraging natural predators and helps to ensure that no single pest population is large enough to create problems.

Growing different plants together – companion planting – brings other benefits. For example, carrot flies are attracted by the smell of young carrot plants, but if strong-scented herbs or garlic/onions are growing amongst the carrots the carrot fly become confused.

A good approach is to plant some flowering plants between crops. Generally, these will attract hoverfly and ladybirds and occasionally bring further advantages – Cabbage White butterflies prefer to lay their eggs on Nasturtiums rather than cabbage plants, thus providing a natural decoy.

Other parts of the allotment can also support wildlife – log piles provide shelter predatory insects and compost heaps are ideal habitats for beetles and centipedes and provide a warm, safe haven for slow worms and hedgehogs.

Further information is available from the Br6thers web-site -

Encouraging Insects


Allotments are great places for biodiversity and an important element of this is the support they provide to insects, and the contribution that insects make in return.

Insects are essential for pollination, decomposition and pest control. Ladybirds, wasps, hoverflies and lacewings prey on aphids and beetles and centipedes feed on slugs, slugs’ eggs and other small insects. 

Insects also help work the soil and also play an important part of the food chain. Birds and other animals feed on insects and these animals also control pests, disperse seeds, etc.

We may be guilty of taking for granted the free services that insects provide so we should help them by providing environments which provide shelter, and by planting crops that provide them with nectar during their barren times of year. 

Local Manure


Manure is a great way of improving soil condition, available from the following local sources... 

  • Raybrook Riding, Bluebridge Road, Brookmans Park, AL9 7SX. Various ages of manure bagged for collection plus a “heap” which may be excavated. Parking for cars and trailers but please telephone before you arrive to check on availability. There is no charge, but donations to Horse Rescue are welcome. 

  • Welwyn Equestrian Centre, Arnolds Farm, Pottersheath Road, Welwyn, Herts, AL6 9SZ. They have two manure heaps which can be excavated for collection but you will need to supply your own bags and call the centre to notify them you are coming.

  • Riding for the Disabled, Rectory Road, Welwyn Garden City (opposite The Red Lion pub on the B197). Collect it yourself and you can make a donation to the charity on your visit.


Green Manures


Autumn is the time to plant green manures. These plants tend to grow quickly and either scavenge nutrients that otherwise might be washed out of the soil or take nitrogen from the atmosphere and transfer it to the soil through their root systems. The roots also improve the structure of the soil, and green manures also prevent weed growth by blocking out light to growing weedlings. 

The main types of green manures are listed below:

  • Clovers can help to fix nitrogen within the soil - should be planted between April and August.
  • Winter Tares (also known as vetches) is a good source of nitrogen and should be planted by September.
  • Phacelia (March - September) and Lupins (March - June) produce flowers which support bees and other insects as well as boosting the soil.
  • Italian or Hungarian ryes (August – October) are good to smother areas that have become overgrown with weeds and grows well through winter (but can provide shelter for slugs and snails).
  • Field beans can be planted as late as November and are good for heavy soils.
  • Mustard should be planted by the end of September and should be dug in after up to two month’s growth (or left as a mulch if the foliage is frost damaged).
  • Mexican marigolds (Tagetes Minuta) can be used as a green manure but its greatest benefit is that it suppresses bindweed and is best sown in spring.

Dig green manures into the soil in the spring while they are still soft and they add nutrients to the soil and enhance the activity of worms and other wildlife below the surface of the soil. Leave for at least two weeks before planting out crops.


Companion Crops


We often think about our crops in isolation, not thinking about how plants interact. In fact, many plants can affect others by attracting insects, repelling pests, and using complementary nutrients. 

Some crops grow well together because of the shape and size, root structure, and need for light. Climbing beans and sunflowers, tomato and fennel, and other combinations are bad neighbours. However, onions can grow happily alongside beans, leeks can be grown amongst celery, and turnips can be grown with peas. 

Tomatoes are believed to deter asparagus beetle, onions and other alliums can reduce attack by carrot fly. Cabbage root fly is dissuaded by herbs such as mint, rosemary or sage. 

Native Americans believed that crops would thrive if they grew squashes alongside sweetcorn plants, and planted climbing beans in between, which grew up on the sweet corn plants, using the stems like canes while fixing nitrogen amongst its roots. This system known as the Three Sisters which is now scientifically understood to be a sustainable method of growing a nutritious combination of crops. 

Rainwater Harvesting

In September 2012, One of our members decided to see how practical it would be to generate a reasonable amount of water for use on a typical plot and after a bit of research finished up going for a structure which was made simply from 2” x 2” timber, a 2m x 2m corrugated plastic sheet for catching the water, some guttering and some water butts 


Initial research suggested that it should be possible to collect a decent amount of water, although doubts remained over the quantity being quoted. However, following the installation of the system, the plot went for about two and a half growing seasons using only rainwater. Pretty impressive!

Having got out of the habit of carrying cans it became a chore when the rainwater eventually did run out of rainwater and there was a return to t lugging watering cans from the tank again (but this was normal for most other plotholders). 

The main lesson is that you need to ensure that you have enough storage containers to collect all the rainwater that falls in the wetter, out of growing season months, so that when you start needing it you have plenty. Two large and four medium sized butts was about the right amount, all of which were full at some time.

Hopefully this offers encouragement to plot holders who are thinking about doing something. With a bit of time and a modest amount of money you can make watering - one of our key tasks - much less of a chore and at the same time make a contribution to using less treated water , something we may all have have to do at some point in the future.

(with thanks to Roger Edgson)