2020 Members' Experiments

Our 2020 experiments are now underway and we're thrilled to have many members signed up to take part in our 62nd consecutive year of running citizen science in organic horticulture.

Below are the details of the four experiments. If you have signed up to one, you will be sent a pack with full information and instructions towards the end of March. 

The experiments will be running throughout the year and we publish the results in 2021.

Experiment 1 - Getting a head start with winter green manures

Many of us know that growing a winter green manure is a good idea. It protects the soil, improves soil structure and prevents nutrients being leached out by rainfall.

Winter green manures are ideally established in early September. However, at this time we are often still harvesting food, so the space isn't ready. By the time the plot is cleared it is often well into October, which is usually too late to get a green manure to reliably establish.

We will be investigating whether it's possible to establish the green manure, yellow trefoil, by sowing it much earlier, underneath climbing French beans. We will try sowing it on three different dates and see if it grows slowly underneath the crop. Once the beans are finished, they are removed and the winter green manure crop should already be established and ready to go in the autumn.

  • We will provide: French bean and yellow trefoil seed
  • You need: 4 x 0.5m2 plots and canes for the beans to climb
  • Time required: 15 minutes a week, from April until October

Submit your results for this experiment here

Experiment 2 - Alternatives to plastic mulches

The benefits of using mulches are numerous. They conserve water and reduce the amount of weeding required. Until recently, many of these mulches were made out of plastic, which can be difficult to recycle and may leave small particles in the soil.

We would like to test some biodegradable alternatives - examining their effectiveness as a mulch and how well they degrade. This trial is being carried out in conjunction with the Organic Plus project at Coventry University's Centre for Agroecology, Water and Resilience, which aims to find out alternatives to contentious inputs, such as plastics, within organic horticulture.

Using the mulches on onion crops grown in a garden setting, we will examine factors such as weed growth, water use and crop yield. We will also investigate how long it takes for the mulch to break down.

  • We will provide: onion sets and mulches
  • You will need: up to 5 x 0.5m2 plots
  • Time required: 15 minutes a week from April until August then final assessment in Spring 2021

Submit your results for this experiment here

Experiment 3 - Can mesh netting reduce potato blight?

Fine grade mesh netting is an invaluable tool in organic growing, particularly for protection against insect pests and birds. Although it is made out of plastic, when it is well maintained it can last for over 10 years, so it can be considered a sustainable alternative to using insecticides.

In 2011, Dr. Charles Merfield, Head of the Future Farming Centre in New Zealand, discovered an unexpected benefit whilst testing mesh as a method of pest protection against the tomato potato psyllid. Not only did the mesh protect against the pest, but the potatoes under the mesh had much lower levels of blight infection in the leaves. The same effect was observed in subsequent years, making it unlikely that this was a one-off result.

However, there remain a lot of unanswered questions, such as exactly why it works (ultraviolet light levels are thought to play a role), and whether it is effective at controlling all types of blight. In New Zealand both early blight (Alternaria solani) and late blight (Phytopthora infestans) are common, whereas in the cooler damper climate of the UK, late blight is much more prevalent.

Currently we are unsure how effective the mesh is against the UK late blight, so will investigate this further by comparing the yields and levels of blight infestation in covered and uncovered crops.

Submit your results for this experiment here

Experiment 4 - A national view of pests and diseases in gardens and allotments

Garden Organic has an extensive membership base of organic vegetable growers around the UK. We would like to ask our members to provide us with a national picture of the key pests and diseases causing losses in vegetable crops grown in gardens and allotments. We plan to run this survey every year, allowing us to examine trends over time and provide alerts to new incidences of diseases.

  • We will provide: recording and identification sheets
  • You will need: a garden or allotment to observe
  • Time required: 30 minutes to fill out the questionnaire

Submit your results for this experiment here