Our District

Green manures

Grow your own soil!  Green crops are grown to build up the soil, rather than to eat (though some can also be eaten.) Any bare patch could be growing useful stuff.

  • Green crops are easy: most grow like weeds
  • They are much cheaper than buying in compost or straw, the only cost is a one-off package of seed
  • There’s no barrowing needed
  • Let at least one plant go to seed, save it, and you’ll never have to buy that seed again.
  • They also keep weeds away from bare soil, and keep the soil structure from collapsing or eroding.

Depending on your situation, green crops can be grown for as little as two weeks, or left to almost flower, or left to go to seed. Before flowering they mainly contain nitrogen; after flowering, it’s predominantly carbon.

Three ways to use green crops:

  • Hoed straight into the soil when young
  • Cut and left on the surface as mulch, with a new crop planted in
  • Cut and collected for the compost heap.

How to grow green manure crops:

  • Ideally, choose a time when weeds are germinating (eg autumn, spring)
  • Clear the bed, lightly fork if the soil is compacted
  • Rake the surface flat
  • Sprinkle on seed to the recommended amount (one handful per

square metre is a rough guide)

  • Rake again lightly/tamp down

Which green manures to use?

Flowering Green crops: Buckwheat (summer), calendula (all year), borage (winter-spring), lupins (winter). These help feed bees and beneficial insects.

Edible Green crops: Broad beans (winter), mustard (winter-spring) Peas (peastraw).

Summer Green crops: Buckwheat, calendula, peas, sweet peas.

Winter Green crops: Broad beans, mustard, lupin, wheat.

Legumes for fixing nitrogen (good before heavy feeders): Broad beans, lupin (cool season); Peas, soy bean (warm season).

Carbon crops for compost: Buckwheat, barley, oats, wheat, sunflower.

Green crop perennials and shrubs for shelter (harvest the prunings for mulch): Tagasaste (tree lucerne), tree lupin, canna.

The Council Green Gardener is available for waterwise garden advice.

Workshops are free for groups of five or more.

To make a booking, call 04 296 4700 or email:

greengardener@kapiticoast.govt.nz