Can I Compost Diseased Plant Matter?

use mildewed leaves for mulch, soil life will sort them out

Yes! Yes, you can. Nature specialises in detoxifying and outcompeting pathogens. A compost heap is full of life, more than equipped for this job. Visualise a bunch of pac-men zooming about gobbling up the bad guys and you’re not far off it. Further biology enters the fray to decompose it all and return it to back as nourishment. Say hello to the cycle of life! Every single moment of every single day, its going on around, above and below us.

Without it we’d be up to our armpits in noxious waste. This is of course, not the case. There is no waste in nature, she relies on cycling nutrients which is why shes so very good at decomposing everything, diseases and all. Pretty neat aye.

The problems comes where there is little or no life, where mono cultures and sterilised environments rule. Young gardens too, arent as strong as established biologically ones. The less diverse a system, the weaker it is and by that I mean the more help it needs to produce crops and fight off disease.

Should you be in one of the above categories, you’d be wise to shift diseased matter elsewhere. Otherwise compost away.

rusty garlic

When I very first experienced garlic rust, I carefully bagged up all the diseased foliage and burned it – my goal to limit the spread. Understandable right, until I learned how tiny and volatile those fungal spores were. They’d already spread far and wide throughout the garden and my cutting them off and bagging them most likely spread them further still. I was performing for my own mental health in this moment – my careful removal, entirely pointless.

Nowadays, there’s 2 ways I go with diseased foliage. I either lay it beneath native plantings, leaving it to decompose in situ or compost it in exactly the same way I treat everything – chop or break it up, mix it up with other ingredients to get as great a variety as possible, then pour on EM or activated compost tea or add some healthy soil.


  1. Jenette Mitai says

    Hi Kath
    What about apples infected with codling moth? I’m now taking other precautions but missed the time frame this time.

  2. Hi what about blight from tomatoes

    • All the same thoughts as above in the article Mark. Its important that you do what feels best in your unique environment. Ask yourself this, “how much faith do I have in my soil biology?”

  3. Always wondered if you could put cat litter into the compost, pooh removed first?

  4. Hey Kath,

    Thanks as always for sharing your wisdom and insight. I am also loving the book!
    I read above in one of the comments about cat litter in a worm farm, does that extend to dog poop in a worm farm? We put ours in a hole in our yard with bokashi zing to break down, but if it were possible I’d love to put it through the worm farm, or a separate worm farm for different application than on the vege garden?

    Also, a separate question, in your book you talk about herbicide free straw/hay, I found a source that said they didnt spray the crop, but sprayed the land prior to planting (with Roundup), I realise this isnt ideal, but is it better than other options? I am not sure if that is normal or better than the average?

    Thanks again, best wishes,

    • Bokachi is a fab way to manage dog poop, as long as the hole isn’t very deep and below the soil life that’ll do the work on it. Check out using wormfarms for doggy doos online – a wonderful way to sort the parasite load of carnivore poop.
      Good question regards which is worse – prior sprays seems less impactful on the foliage of the crop for sure. We could go down a rabbit hole of wondering about all life connections and what it means to the health of grasses grown in that environment. To be sure, you’d need to test it, or do as I do – go with your gut feeling. Your soil and plants will show you what they think. At the least let it sit and rot and add a bit of life perhaps – EM etc
      I used ‘spray free’ spoiled hay once, and all my melons yellowed and died toute suite. I’m now very cautious getting inputs in and as much as possible forage in my garden and beyond where I know for sure. Trust yourself here.
      Hope this helps

  5. Hi Kath
    I appear to have lemon scab and was wondering if you have a way of fitting this annoying problem organically. I know I can still use the juice but want the zest as well.
    Thanks for your help

    • Verrucosis is a fungal disease so your main port of call is to keep it pruned to an open shape for good airflow, consider airflow beneath the tree as well – mulch is better than plants under lemons for this reason. Build beneficial fungi with EM and seaweed or fish sprays as well as keeping a fungal rich soil with ramial chip mulch (mulch made from small twigs and branches). Dont overfeed or use artificial fertilisers, stick to homemade compost, seaweed or well rotten manure – I have a blogpost with how to grow citrus detailing a feeding regime. Plant a true lemon like a Yen Ben or Lisbon to use for zest, in another part of the garden. As they arent as susceptible to veruccosis as Meyers are.
      Most of all, accept that the disease is in the house now and you may limit it but unlikely get rid of it unless you are going to go down the commercial road of 4 copper sprays a year. The downside of this is that it will kill off all the beneficial fungi as well, leaving the tree dependant on you and with this job ever more.