Re-using potato compost

Answered by Lynn Posted in Category Soil, Feed & Fertilisers

Dear Lynn

I have a large amount of compost from this years potato harvest and would like to recycle it. The potato compost also had potato fertalizer and farmyard manure.

Could I use this for planting mini fruit trees into.


Dear Andy

It is always a dilemma what to do with the potato bag compost, most of the advice given to gardeners is not to re-use it, mainly because of the risk of transmitting pests and diseases but saying that I always try to reuse soil wherever possible.  Compost is too expensive and it would make gardening unsustainable if we threw everything away.

There are a few factors to consider and things to do to make your compost reusable but if you follow these guidelines hopefully you won’t have any problems with your mini fruit trees.

Potatoes are members of the Solanaceae family the same as tomatoes and both are subject to blight. If your potatoes had any sign of blight this year do not reuse the soil anywhere in your garden.

Was there any sign of any others pests and diseases in the soil or on the potatoes? If so, these should be treated accordingly and then careful consideration given on reusing the soil depending on the problem.

In general if you wish to re-use any soil always think about crop rotation – for example never use the same soil for growing the same vegetables year after year.  Always rotate them to avoid the build up of pests and diseases.

Potato plants are greedy and deplete minerals and nutrients from the soil even after one season. Heavy watering can also wash the nitrogen out of the soil so your soil will need feeding to replenish it before planting up your trees. Add more organic material such as well rotted manure or chicken pellets into the soil or add Bonemeal in the planting hole when planting up your trees followed by Fish, Blood & Bone or Growmore sprinkled on the top.

If planting your mini fruit trees in containers choose a good size and ensure that it is big enough for your tree. Place some crocks (small pieces of broken concrete, clay pots, or polystyrene) in the bottom of the containers to retain moisture.

Remember to water in well and continue to water on a regular basis, more so with newly planted trees. The soil may be dry around the roots even when the surface appears moist.  Rain water very rarely waters pots enough and additional irrigation is required.  Harrod Horticultural sells these Deep Drip Tree Watering Stakes – I recommend these for all potted trees and shrubs to ensures that water reaches the roots where it is needed most.

Good luck with your new fruit trees and I hope you remain pests and disease free.


Lynn Burton
Horticultural Adviser


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