Re-using potato compost
I have a large amount of compost from this years potato harvest and would like to recycle it. The potato compost also had potato fertiliser and farmyard manure.
Could I use this for planting mini fruit trees into.
Thanks
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. Raised beds are great for this as its easy to just change what you grow in each bed every year.
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 or bone or Growmore sprinkled on the top. Adding soil improvers will also prove beneficial.
If planting your mini fruit trees in containers choose a good size and ensure that it is big enough for your tree. 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. There are various watering products available to help main regular watering of the pots ensuring 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.
Regards
Lynn Burton
Horticultural Advisor
Soil Improvement FAQ's
1) Can I re-use potato compost next year?
Yes - if your crop was healthy and blight-free. Refresh nutrients and use it for different crops (avoid potatoes/tomatoes).
2) Is re-used potato compost good for mini fruit trees?
It can be - blend 50:50 with fresh compost or topsoil, add bonemeal in the planting hole, and apply a balanced fertiliser through the season.
3) What should I add to tired potato compost?
Well-rotted manure or garden compost, plus a balanced granular feed (Fish, Blood & Bone or Growmore). Add grit if drainage is poor.
4) Can I use old potato compost for tomatoes?
Best not. Tomatoes are in the same family and share diseases. Rotate to a different medium.
5) Is potato blight carried in compost?
If blight was present, avoid re-use to reduce risk of spreading disease.
6) What are the best crops after potatoes in re-used compost?
Leafy greens, salad crops, herbs, bulbs and many ornamentals.
7) Can I use spent compost as a mulch?
Yes - apply 3–5 cm around plants, keeping it off stems.
8) How do I store used compost over winter?
Keep it covered and off the ground to prevent nutrient leaching and weed seeds blowing in.
9) Do I need to sterilise old compost?
Not usually. If you had pests (e.g. vine weevil), treat accordingly and don’t re-use for susceptible crops.
10) How often should I feed plants in re-used compost?
In containers, plan a slow-release feed at planting plus liquid feeds during peak growth.
