Roehampton Garden Society

Tag Archives: GreenManures


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Trying out Green Manures

You may have read about using Green Manures to improve your plot. Timing can be difficult, however, and the variety of options confusing.

Green manures, often sown in late summer or autumn, take up nutrients, preventing them being washed away by winter rain. When dug in the following spring, they release these nutrients back into the soil. It’s a nutritional feast for your soil.

Different varieties can be used throughout the year – some good for getting a bad patch back into cultivation, and others good for productively filling a patch after a crop has finished. Sown from seed in any patch you want to improve, they should grow within 6 weeks and have the extra advantage of keeping down the weeds while they do so!

Here’s a mixed crop of winter tares and rye, planted last November, flourishing on Site 3 in January.
Digging up was straightforward – the roots weren’t too long! Cut off the roots before digging in, and leave for 2 weeks before planting…

Here’s some good green manure advice from the RHS – for instance in an area with club root, don’t use mustard green manure. Read more from the RHS..

So – if you can see a time gap between crops or just want to plan ahead to improve your soil, take a look at the selection of different green manures in the Store. There will be one to fit your plans…


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February jobs on your allotment

Maintaining soil and structures and planning ahead

  • Prepare for early vegetable crops by warming soil before sowing, covering seedbeds with polythene or cloches.
  • Keep off wet soils to avoid compaction. Use long boards as walkways, to spread your weight.
  • If the soil isn’t too wet, start to dig in overwintered green manures (e.g. Grazing Rye, Winter Tares or Overwinter Mix sown previous August to November) as the frost should have killed them off.
  • Continue to tidy up and re-cut grass path edges if the grass has encroached on your plot.
  • Continue to add layers of un-composted stable manure to your heap.
  • Apply 2” layer of well-rotted garden manure (Country Natural ) or garden compost around perennial crops such as Jerusalem artichokes and rhubarb.
  • Club root is a fungal infection that affects the roots of brassicas and is endemic on allotment sites. To reduce the risk of infection, apply lime to the soil at 270g per sq m, 8oz per sq yd. where brassicas are to be grown. Do not add composted manure at the same time. Calcified Seaweed can be used as a natural alternative to lime, fork it in 140g per sq yard / metre about a week before planting.
  • Apply general fertilizers such as Growmore, (inorganic) or fish, blood and bone or seaweed (organic). Poultry Manure pellets are a non-chemical alternative to Growmore. They are slower to release their nutrient content, some of which will not become available until the soil warms up.
  • Organic Rock Dust and Bio Char soil improvers replace minerals in the soil lost to leaching..
  • Top-dress all tree and soft fruit with sulphate of potash.
  • Clean pots and trays by scrubbing in hot, soapy water before starting to sow new seeds. Pests and diseases can overwinter in old potting compost, surviving to damage newly emerging seedlings.
  • Prepare a new asparagus bed by digging in well-rotted manure and order asparagus crowns

Sowing and growing

  • Chit potato tubers in a light, cool, frost- free place.
  • Outdoors, sow broad beans, spring garlic, peas and Jerusalem artichokes.
  • If mild, also sow spinach outdoors.
  • Sow sweet peas under cover in deep pots or Root-trainers.
  • Pot on and pinch out autumn-sown sweet peas to encourage side-shoots to form View on Gardener’s World
  • At the end of the month sow tomatoes under cover.
  • Sow sweet and chilli peppers from mid February in a heated propagator or sunny windowsill. (Chillies need 21 degrees to germinate.)
  • Sow radishes in cold frame or greenhouse beds.
  • Sow aubergines in a heated propagator or sunny windowsill.
  • Sow celeriac in deep modules in a heated propagator or sunny windowsill.
  • Sow cabbage under cover.
  • Sow early leeks in deep pots under cover.
  • Sow early lettuce and keep in cold frame or greenhouse for earlier harvest.
  • Sow hardy annuals for companion planting such as calendula and tagetes indoors for earlier blooms.
  • Sow mustard and cress in a small seed tray on a warm windowsill for pickings in just a few weeks.
  • Spray dormant fruit trees and bushes with plant oil-based winter tree wash to kill overwintering eggs of aphid pests.
  • Force rhubarb for sweeter, earlier stems by covering crowns with straw and then a container, such as an upside down bucket, to exclude light.

Harvesting

  • Purple sprouting broccoli and kale may be possible to harvest.
  • This month, complete pruning of apple and pear trees, gooseberries, redcurrants and prune out a quarter of blackcurrants’ older growth at ground level.
  • Prune autumn raspberries, cutting all canes down to the ground.

Pruning

  • If summer-fruiting raspberries have grown above their supports, cut back to one or two buds above the top wire.
  • After pruning, apply a general-purpose fertilizer to tree, bush and cane fruit and mulch with well-rotted manure or garden compost.
  • Start pruning bush roses at the end of the month.
  • Vine pruning must be completed by the middle of the month.

Gardening for Wildlife

  • Continue to top up bird feeders. Avoid giving large foods, such as peanuts, as nesting time approaches.
  • Put up nesting boxes.
  • Avoid turning the compost heap until mid-spring as it could be sheltering hibernating frogs, small mammals and insects.


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November jobs on your allotment

Maintaining soil and structures and planning ahead

  • Continue to clear all plant debris from plots. Do not add blighted tomatoes to your compost, but burn or take to the dump.
    Empty compost heaps and use the well-rotted dark crumbly material.
  • Apply a 5cm layer of well rotted compost or manure to bare plots or cover bare areas with brown cardboard weighed down with damp grass clippings.
  • Prepare a winter compost trench for next season’s moisture loving plants such as sweet peas, runner beans or squashes. Dig a trench a spade deep and fill with kitchen vegetable waste covering each additional layer with soil.

Sowing and planting

  • Continue to sow overwintering broad beans.
  • Sow hardy peas either straight into the ground under fleece or 3 to a 9”pot to be planted out when the roots reach the bottom.
  • Sow a gutter of peas in the green house or under cloches for salad or risotto at Christmas time.
  • Sow cut-and-come-again salads in a sheltered spot or green house.
  • Finish planting onion sets and garlic.Garlic needs a chilling period so plant now. With current wet winters plant on a ridge to aid drainage.
  • Sow dill, chives and parsley now on a sunny windowsill.
  • Order bare root trees now for the best selection.
  • Fix grease bands to fruit trees to protect against winter moth. To help control pests and diseases spray fruit trees with winter wash on a calm, dry day.
  • Once leaves have dropped and before bud break in February spray fruit trees with winter wash on a calm, dry day. Spraying helps to reduce overwintering pests.
  • Start winter pruning of apples and pears.
  • Keep overwintering brassicas covered with netting to prevent pigeon damage.
  • Stake tall brassicas against wind damage.
  • Sow green manures early in the month such as grazing rye.
  • Clean the greenhouse to maximise light levels and before the water is turned off in December.

Harvesting

  • Start to harvest winter cabbage, Brussels sprouts, leeks and kale. Wait until after frosts for parsnips as they will be sweeter.

Pruning

  • Begin winter pruning of apples, pears and vines.
  • Prune overgrown blackcurrant bushes- remove a third of the oldest stems to ground level.
  • Fruited canes of blackberries and hybrid berries such as tayberries and loganberries should be pruned to ground level.

Gardening for wildlife

  • Remove surplus dead leaves from ponds to prevent decomposition pollution.
  • Clean out bird boxes of old nesting material so they may be used as winter roosts.


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August jobs on your allotment

Maintaining soil structures and planning ahead

  • Green manures such as Mustard and Phacelia and Grazing Rye can be sown now.
  • Continue regular weeding to avoid build-up of work later.

Sowing and Growing

  • Sow oriental vegetables such as mizuna, pak choi and mustard greens for salad leaves- they bolt less at this time of year.
  • Sow parsley to last through till spring on a sunny windowsill.
  • Sow Swiss chard and perpetual spinach at the beginning of the month.
  • Make a last sowing of beetroot at the beginning of the month.
  • Sow fast-growing ‘catch crops’ for autumn use, such as radish, lettuce, rocket and turnips.
  • Plant out winter brassicas, broccoli, kale and cabbbages in soil which has been limed at least 6 weeks before, to reduce club root infestations.
  • Plant new strawberries now, either as detached runners or new plants.
  • In dry weather keep runner beans well-watered twice a week to aid setting.
  • To reduce risk of tomato blight, water directly onto the roots not the leaves.
  • Feed courgette plants weekly with a high potash liquid feed to continue fruiting.
  • Summer prune trained fruit trees such as fans, espaliers and cordons.
  • Prune plum and damson trees after fruiting. On grape vines shorten fruit bearing branches to two leaves beyond the fruit bunch.
  • Prune out fruited canes of summer raspberries.
  • Tie in new canes on raspberries and blackberries.
  • On grape vines shorten fruit bearing branches to two leaves beyond the fruit bunch.
  • Cut back chives if showing signs of rust and new shoots will quickly appear. Remove mint plants showing signs of rust. The disease will persist over winter and re-infect new plants next year.
  • Pick off and destroy rosemary leaf beetle which are active at this time of year.
  • In the greenhouse avoid splashing water onto leaves. Moisture triggers spore germination of fungal diseases.

Harvesting

  • Harvest sweet corn when a grain exudes milky juice when tested with a fingernail and the whiskers are brown.
  • Harvest onions and shallots when the stems are dry and papery.
  • Start harvesting runner beans, parsnips and cucumbers when ready.
  • Complete harvesting of second early potatoes and begin to harvest main crop potatoes as they begin to flower.
  • Harvest early ripening apples and pears.
  • Harvest carrots, but leave protective insect mesh on carrots until autumn.

Gardening for wildlife

  • Leave some flower seed heads on plants as source of food for wildlife.
  • Cut and shake ripe seed heads of annuals over suitable patches of bare soil for flowers next year.