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White Mustard Seeds - Green Manure

Botanical - Brassicaceae


50g (covers 18m²) at 2.77g per m²
Usually despatched within 24 hours
See "Delivery Charge" tab below
Current Stock:
Out of stock
Price £1.49

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Sorry but this item is currently unavailable.

Please check back at a later stage.

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50g covers 18 metre square (approx 7050 seeds) at 2.77g per m²

Other Names - Sinapis Alba…

White mustard prefers to grow in the cooler months and is promptly killed by frosts. This makes it an ideal green manure for people who prefer not to do too much digging as the dead autumn leaves can simply be left on the surface as a mulch and during the cold winter months the valuable organic matter will gradually be incorporated into the soil with the help of worms and other bugs.

  • Excellent for improving soil structure.
  • Fast growing.
  • Minimal digging required.

Suitable For - Green manure in vegetable and fruit gardens, groundcover, weed suppressant

Sowing Months - March - September

Flowering Months - N/A

Growing Period - 7 - 8 weeks or anytime before flowering

Soil Preperation

Remove weeds and large stones. Lightly dig if needed, rake the soil to a fine tilth.

General Information
Habit Annual Type Brassica
Height 30 - 60 cm Hardiness Half hardy
Position Full sun, partial shade Soil Ph  
Soil Type Tolerates most soils Coverage 2.77 g per 1 metre square
Distance Between Plants Scatter evenly Depth 1 cm
RHS Bee Friendly No RHS Award Winner No

Sowing Guide

Scatter the seeds as evenly as possible on the surface of the prepared seed bed.
Lightly rake the surface to cover the seeds.
Water the newly sown seeds well.

Growing On

Water the young seedlings well until established.
Established plants need regular watering especially in dry periods.
The plants are frost tender and will be killed by the first autumn frosts.

Digging In

The plants can be cut down using a garden spade or shears, 7 - 8 weeks after sowing or just before flowering.
Leave to wilt on the surface of the soil for a few days before digging in.
Dig the plants into the soil at the depth of 20 - 25 cm with a sharp spade or rotovator.
If killed naturally by autumn frosts, dig in as normal or if preferred simply leave the organic matter on the surface to decay over the winter months. During this time the plant material will gradually be incorporated into the soil with the help of bugs and worms. In spring dig in any remaining organic matter.
Avoid growing any vegetables in the soil for at least 3 - 4 weeks after digging in so that the green manure has time to decompose.


White mustard belongs to the brassica family and therefore should not be followed by any brassica vegetables such as cabbage, sprouts, cauliflower, radish, broccoli etc. as this can lead to a build up of brassica pests and diseases.

Delivery Information

All products on this website are for delivery to the UK only.

(Including Northern Ireland, the Highlands & Islands, Scilly Isles, Channel Isles and the Isle of Man). Delivery charges to these areas are the same as UK mainland stated below (with no additional surcharge). Delivery however may take longer than the times stated due to weather, distance etc.)

FREE DELIVERY on all orders over £9.98

When applicable, free 2nd class delivery will be automatically calculated at checkout.

STANDARD DELIVERY - Royal Mail 2nd Class (3 - 5 working days) - £0.95

For orders under £9.98, the "Standard Delivery" charge will be added automatically at checkout.

FAST DELIVERY - Royal Mail 1st Class (1 - 2 working days) - £1.52

If preferred please select this delivery option at checkout.

For further information please visit our Delivery, Postage & Packaging page.

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For full details please visit our Your Right to Cancel page.

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If however you receive goods that have been damaged, incorrect or missing, let us know within 72 hours of receiving the goods and we will either fully refund you (including postage costs), promptly send you a replacement or credit your Groseeds account, depending on your preference.

For full details, including how to contact us, please visit our Returns & Refunds page.

Faulty Goods.

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If however within the 12 months you find the goods to be faulty please contact us ASAP so that we can resolve the issue promptly. Full instructions, including how to contact us can be found on our Returns & Refunds page.

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