First Hand Case Study: Mike Fisher talks about Winter Cover Crops for Market Gardening
Veg grower, Mike Fisher, has not applied any compost for the past five years, relying instead purely on plant mixtures as green manures.
This year, 2021, Mike celebrates 30 years as a grower. He began with a bare field and launched a veg box scheme back in 1994, one of the first organic growers. For a time he sold wholesale to Abel & Cole and Riverford but now concentrates on the local market, harvesting once a week and supplying 130 boxes a week direct to households within a 10 mile radius. There’s a variety of veg, including sweetcorn, leeks, plus tomatoes, cucumbers and salad leaves in polytunnels.
Unusual in his choice of growing organically, Mike was also a pioneer in the use of green manures and turned to Cotswold Seeds in 1992 because in those days they were the only seed merchant offering these mixtures.
‘The first crop I used was forage rye to increase organic matter and soil life,’ Mike remembers.
Now Mike uses a range of green manures in rotation, with four year of vegetables and one year of forage rye and vetch and red & crimson clover for building organic matter and adding diversity. It starts with potatoes and these come out in September. Then garlic and winter onions go in until July. The red and crimson clover goes in before August and comes out in March before brassicas.
‘It’s a case of organising the rotation to provide a block of land for green manures,’ Mike says. ‘There are early and late planting and different harvest dates for veg so you can play about with the timing and the veg successions.’
He’s experimented with buckwheat to control couch grass for the Organic Research Centre, which had some success. This year he sowed later so doubled up with phacelia and at the time of writing has yet to see if it smothered the couch. He’s also used a Cotswold Seeds Herbal Ley. ‘It might seem odd for veg grower to plant herbs but it’s important to bring up minerals and trace elements from the soil.’
Mike also adapts seed rates. ‘We tend to use double seed rates to get good coverage and smother all our annual veg weeds. Having been growing intensive veg for 30 years it can be an issue, so worth the extra cost.’
The 2020 winter cover crop of radish, mustard, vetch, crimson clover went in the ground on 20 August. The crop was sown straight after two thunderstorms when the soil temperatures were high. A couple more thunderstorms made conditions ideal for establishment. The land had a ley on it recently, so some fertility was carried over from that and just two months later the cover crop was vast, reaching waist height.
‘It’s gone in ahead of next year's leeks,’ Mike says. ‘It will come out late February or March, flailed off then ploughed or rotavated.’
The results of Mike’s rotation are impressive. The soil drains well and has a high pH of 7.8 and organic matter is now 9%. ‘It was 5% immediately after stubble, so we weren’t starting from nothing, but the improvement is very impressive.’ It’s up to 20% in the ½ acre of undercover polytunnels.
The green manures not only build soil organic matter but help with water retention too. ‘For summer veg crops that is very important as well,’ Mike says.
The proof is in the products. Many customers have been with Mike since the ‘90s and this year he has been inundated with new inquiries. ‘I like building loyalty,’ he says
He’s also a loyal customer of Cotswold Seeds. ‘I have stayed with them for decades because of the great service and the quality of information and technical advice.’
Date Posted: 22nd March 2021
