Friday, 23 July 2010

Growing Green Manure "White Mustard"

  • Mustard is a very quick growing green manure, that can be sown from March – September and has a growing period of 1-2 months and can reach 60-90cm. 
  • The half hardy annual grows on most soil types and produces large volumes of green matter and residual fibre which is particularly good for those soils that lack organic matter it helps to improve soil texture and moisture retention. 
  • It isn’t a nitrogen fixer though, but is still a very worthwhile leafy green manure. . 

  • As it is part of the brassica family don’t use mustard in crop rotation plan before sowing a brassica crop as this increases the likelihood of diseases. 
  • Just a light tilling is all that is required if the bed has been used for another crop earlier that year, otherwise dig to a spade depth, if it is a light soil then a garden fork will be sufficient and makes lighter work.
  • Rake flat and even and use the opportunity to remove any large stones or other intrusive items, such as glass or large clay lumps.

  • Broadcast at the rate of 4grams per square metre. This is not intuitive over a large area, however most of us can manage to spread 4grams evenly over a square metre.
  • Mark out the bed to be sown into square metre blocks, perhaps using canes laid out or twine or hose pipe.
  • Separate the seed into 4gm lots, scales are useful but if doing it on an allotment then scales are not always readily to hand. If you have bought 20 grams of seed for 5 square metres of bed, then get 5 small containers of the same size and split the seed visually into 5 equal amounts, as long as they are visually the same then it is accurate enough. The small yoghurt pots beloved on allotments are good for this.
  • Now take each 4gms of seed and scatter it evenly over a marked-out square metre, not too difficult and don't worry if you weren't too accurate as another chance to get it right is still available.
  • Take a rake and spread the seed into an even spread and rake it into the soil; some will remain on top of the soil but that will still be satisfactory as long as the birds don't take the seed and the slugs don't eat the germinated seedlings.

  • Put some sort of cover over the seeded beds, netting is best and only needs to remain until the crop is under way when it will look after itself. 
  • Bird scaring devices, such as George Michael CD's attached to a string and dangling of a large pole, have been known to be scaringly effective.

  • After 4-8 weeks of growth chop down the plants and cultivate into the top few inches of your soil. 
  • On sandy ground let mustard reach 40cm in height or wait for the first flowers to appear before digging in. This will produce more fibrous plant matter which can help very free draining soils retain more moisture and nutrients. 
  • Some authorities suggest chopping down the crop and then leaving it alone to get a second growth for later repeat cutting before ploughing/digging into the soil.
  • Once dug into the soil, the worms do the rest of it for you.

  • The seeds produced are used to make the yellow mustard sauce that Americans use on their hot dogs, but once it has gone to seed it will be back as a weed each year to trouble you for many years afterwards.
  • As part of the brassica family, repeated sowings and digging in of the mustard at 4-8 week intervals may help to clear infected land of club-root. 
  • Mustard is part of the brassica family and it will activate the dormant spores of this fungal disease, and will allow the grower to break its life-cycle as the plants are prematurely destroyed. An excellent plus, as club-root disease can remain dormant in the ground for up to 20 years but this is not a quick fix and it will take a number of repeated sowings. 
  • Another control is that if allowed to fully mature it can clear a site of wire-worms; these insects can devastate a crop of potatoes. 
  • Wire-worms feed on the dug in and decomposing mustard crop, they mature quickly and fly off as beetles to lay in pasture, so the cultivated area is now clear.


  1. As a bird scarer, I find your choice of CDs a bit 'queer'!
    Martin, Droitwich.

  2. Actually it's a toss-up between George Michael and Boy George; but that could be because they are both easily had at car-boots etc.