Planting mustard: sowing & mustard as green manure

Fredrik
Fredrik
Fredrik
Fredrik

Having grown up in the countryside, nature and self-sufficiency have always been big part of my life. I live and breathe nature and had the chance to delve even deeper into this interest during my studies in agricultural systems science at university.

Favourite fruit: apples, blackberries and plums
Favourite vegetables: potatoes, peppers and courgettes

Mustard is ideal as a green manure in the autumn. This prepares the bed in the best possible way for the next season. Here you will find everything about sowing and using mustard as a yield crop or as a green manure.

Mustard plants in the garden
Mustard is used in the garden as a useful crop or as green manure and soil improvement [Photo: Galina Savina/ Shutterstock.com]

The use of various plants as green manure is becoming increasingly popular in home gardens. Mustard is also suitable for use in many ways. Find out in this article how to go about planting mustard, why it is particularly suitable as a green manure and how it effectively suppresses weeds.

Planting mustard: location and timing

There are three varieties of mustard: white, brown and black mustard (Sinapis alba, Brassica juncea and Brassica nigra). In principle, mustard can be sown all year round, as long as it is frost-free. So the best time is after the last frosts in May until autumn. This applies equally to all three types of mustard. However, if you want to harvest and use the mustard seeds, you should sow them in good time. To do this, you can pre-sprout mustard plants on the windowsill in early spring and put them in the garden as seedlings. If you want to use mustard as a green manure or intercrop, this can happen any time after the harvest of the previous crop.

In general, mustard can be grown in any full sun to partially shaded location as it is very undemanding. Ideally, the soil should be humus and somewhat calcareous, but mustard can also be used as a soil conditioner on poor-quality soils. It breaks up soil compaction with its strong, deep roots and transports organic material into deeper soil layers. Almost any other vegetable is suitable as a neighbour for mustard; only mixed culture with other cruciferous species is not advisable because of possible disease transmission.

Tip: One of the deciding factors in which variety is ultimately selected is the amount of space available. If you have a lot of space, you can easily use black mustard, which grows up to 200 cm tall. On the other hand, if you need a green manure or intercrop for your raised bed or balcony garden, it is better to choose white mustard, which only grows 70 cm tall at most.

Growing mustard: sowing and planting mustard

Those who want to harvest mustard seeds as a spice should proceed as follows: the mustard can be planted or sown.
If mustard seeds are to be sown, a somewhat narrower planting distance applies than for young plants, as not all grains will germinate – so 10 to 20 cm is best. This additionally protects against losses by birds, as the grains are readily eaten by them.
Those who want to plant mustard seeds can start from mid-May. The seeds can be placed in loosened soil and then covered with about a finger’s width of soil. After that, the seeds still need to be well watered so that they begin to germinate. If it is a little drier, it is recommended to water regularly. The first seedlings should be visible after a few days. If the plants have finally germinated and are too dense, some can be removed to give the remaining plants enough space.

Mustard seeds
You can either plant mustard or sow it [Photo: Sunny_Smile/ Shutterstock.com]

Mustard seedlings are not commercially available. However, if you have already grown small plants around March time, you can transplant them from May with a planting distance of about 15 to 20 cm from each other. To do this, dig a small hole with a trowel and place the seedling in it. Cover the hole with soil and water the plant well.

During growth, mustard is a fairly unpretentious plant but should be watered regularly in drought conditions. The first leaves can be harvested just three weeks after the germination of the plants, for example, to make a delicious salad.

The seeds grow in pods and are usually ready for harvest in September or October. If you shake the pods and they rattles inside, they are ripe and harvesting can begin. To do this, simply detach the pods from the plant by hand, open them and shake out the grains. For a large crop, it’s easier to place the collected pods in a bag and tap them with your hand or a rolling pin to loosen the mustard seeds.
Mustard plants sown or planted late and which are not ripening can also be enjoyed as a leafy vegetable. Thus, they are a perfect culture for the autumn. In Indian cuisine, mustard plant is used for spinach-like vegetable dishes.

Summary: Growing mustard as a vegetable

  • Direct sowing from mid-May or pre-planting indoors/early bed/greenhouse from March, then planting out from May onwards.
  • Water regularly during drought
  • Harvesting mustard seed from September/October
  • Late-sown mustard no longer flowers and forms seed but can be eaten as a leafy vegetable

Tip: If you want to grow mustard in a container to harvest the seeds, make sure the plant gets plenty of sun and is well supplied with nutrients and water. A nutrient-rich compost is ideal for supplying the plant with what it needs. Our Plantura Organic All Purpose Compost combines these positive properties and is also environmentally friendly and made from peat-free materials.

Organic All Purpose Compost, 40L
Organic All Purpose Compost, 40L
star-placeholder star-placeholder star-placeholder star-placeholder star-placeholder
star-rating star-rating star-rating star-rating star-rating
(4.8/5)
  • Perfect for all your house, garden & balcony plants
  • For strong & healthy plants as well as an active soil life
  • Peat-free & organic soil: CO2-saving composition
£16.99

Planting mustard as green manure

The purpose of green manure is to replenish depleted soil with fresh nutrients and organic matter after a heavily nutrient-depleting crop. Green manure can be used on vegetable beds as well as to prepare lawns or flower beds.
Thanks to its deep roots, mustard also loosens the soil structure and thus improves soil life. Accordingly, green manure with mustard has a multiple positive effect.
Mustard as green manure can be sown throughout between May and October.

All mustard varieties can be used as green manure, even the well-known yellow mustard is suitable as green manure. It should be sown late in the year, but ideally immediately after the harvest of the previous vegetable. Then, when the mustard has grown tall enough, you can simply cut it down to ground level and leave it on the bed. The best time for this is before flowering, because then no seeds have formed. Otherwise, these could sprout again next year and disturb the bed. If the mustard is sown very late and has not yet formed flowers before the first frost, the plant can also remain whole and does not need to be pruned. It then freezes and remains on the surface by itself. Thus, the plants remain on the bed throughout the winter, protecting the soil and soil life in this way from severe frost, sun and erosion. Finally, in the spring, the rotted mustard plants can be buried in the soil and provide organic material for humus build-up.

Mustard plant seedlings grown outdoors
Mustard germinates only a few days after sowing and grows very quickly [Photo: Sunny_Smile/ Shutterstock.com]

Caution: Mustard is a cruciferous plant. It is suitable as a green manure and catch crop on all land if no other crucifer has been grown in the previous three years and no crucifer is to be grown in the next three years. Otherwise, there is a risk of disease transmission. It is therefore essential to pay attention to crop rotation in your own garden.

Sowing mustard to combat weeds

Mustard could almost be called a miracle plant because of its diversity. In addition to its many benefits for soil structure and nutrient balance, it is also very fast growing. This means that there is little chance for weeds once mustard has germinated. Mustard grows very quickly and forms a dense ground cover, suppressing the slower growing weeds. Mustard can always be sown in an open field to suppress weeds. It cannot grow over weeds that are already tall. These must be weeded by hand before sowing in the traditional way.

Subscribe to the Plantura newsletter