GroChar Soil Improver

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Alys Fowler shows how to use GroChar:

Application guidelines

Our GroChar Soil Improver is 90% biochar activated with 10% seaweed, wormcasts and mycorrhizal fungi. It can be used in a number of ways.

Adding to your own seed or propagating compost

We suggest adding the soil improver at a rate of 10% by weight to your existing compost. Mix in well to ensure an even distribution. One of the many benefits is that the product has a high water holding capacity, so you will almost certainly need to irrigate less frequently than usual.

Adding as a bulk soil improver

There is no set limit to the quantity of soil improver you can add to topsoil. Research shows that bulk applications of as little as 250 grams per square metre will bring positive results. However, if you apply each year then the levels and benefits will build up over time.


Professional growers who took part in the independent trials we commissioned in 2012 used a standard application rate of 1kg per square metre on the basis that this quantity is likely to show a clear benefit, yet still remains affordable. See the results here:

For top-dressing established shallow rooted plants

Incorporate a good few handfuls into the topsoil immediately around established plants, trees or shrubs to avoid wind or rain blowing it away. Around 1kg is a good amount to add to the base of an established tree.

For planting out to minimize transplant shock

Add a generous sprinkling around the root zone of the intended planting area. Depending on the crop you are growing you can add the soil improver in the following ways:

For plug plants add a heaped teaspoon (5g) per plant at planting out.

For larger plants like squash or tomato add a heaped dessert spoon (10g) per plant.

You can also add a generous sprinkling along the row before or after planting at around 1kg per square metre. This is often a more practical option, particularly if you are planting mechanically.

When planting out small trees or shrubs mix the soil improver into the soil or compost at the base of the planting hole. Alternatively, loosely incorporate into the topsoil around the tree or shrub after planting.

As start-up ingredient / accelerator during compost making.

Sprinkle the soil improver in layers as you build up your heap.