Green Manures for the Greenhouse



Green Manures

green manures for the greenhouse Green manures are crops grown not to eat, but to improve and protect the soil.

The borders are usually full in spring and summer, but there is a good choice of green manures to fill a winter gap, eg. winter tares (Vicia sativa) which fix nitrogen in the soil, and grazing rye (Secale cereale) which helps to mop up excess nutrients.

Growing one of these is far better than leaving the soil to become dry and lifeless, and it will eventually provide organic matter when the crop is dug in or hoed off.

The chart below lists some of the green manures suitable for a greenhouse, and gives their hardiness, appropriate sowing times, and number of weeks needed in the ground to provide winter cover or enough growth to dig in.



Green Manures for the Greenhouse

Plant

Botanical name

Sowing time

Weeks in ground

Hardiness

Buckwheat

Fagopyrum esculentum

Early spring to late summer

4 to 8

Susceptible to frost.

Fenugreek

Trigonella foenum graecum

Early spring to early autumn

4 to 8

Survives light frost: should survive over winter in unheated greenhouse in most areas.

Phacelia Tanacetifolia

Phacelia tanacetifolia

Early spring to early autumn

4 to 8

Survives light frost: should survive over winter in unheated greenhouse in most areas.

Mustard

Sinapsis alba

Late winter to mid-autumn

2 to 4

Survives light frost: should survive over winter in unheated greenhouse in most areas.

Winter tares

Vicia sativa

Early spring to early autumn

6 to 10

Hardy.

Grazing rye

Secale cereale

Mid to late autumn

2 to 4

Hardy.


Acidity and alkalinity

Use a pH testing kit to measure the acidity or alkalinity of the greenhouse soil at the beginning of the season, particularly if your plants have suffered from any deficiencies or disorders the previous summer. Most crops prefer a pH of about 6.5. Adding compost or manure to the border every year will gradually make the soil more acidic. Adding lime or calcified seaweed makes it more alkaline.


Organic fertilizers

On poor or overworked soils, addition of organic fertilizers such as hoof and horn or blood, fish and bone may be necessary.

28. November 2010 by Dave Pinkney
Categories: Garden Management, Greenhouse Gardening, Manures and Fertilisers | Tags: | Comments Off on Green Manures for the Greenhouse

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