Plant Doctor Archive

Compost or sludge?

I'M having problems making decent compost. All we get is a rather horrible sludgy mess, but even more alarmingly, it is full of great big larvae that I suspect are grass grub larvae. Is this likely, and how can I get rid of them? They are like very large maggots with brown heads, and some have little "legs" or feelers just below their heads. Is there any point in adding our sludgy mess to the garden?

GRASS grubs are unlikely to lay their eggs in your compost heap, so the larvae you describe are probably from some large fly or perhaps a beetle. The main problem is your compost heap is very sick - it needs a dose of roughage!

Some materials, such as kitchen scraps and lawn clippings, have a very high water content and you need to mix them with drier or woodier materials like sawdust, bark, shredded newspapers and cardboard, or hedge clippings.

While you need moisture for good composting, you do need lots of air too. Make sure you have good drainage at the bottom of the heap - you could use twigs or small branches for the bottom layer. Check there are plenty of holes around the side of the heap for air to get in as well as a lid to keep the rain out.

If you have the energy (and time) you could turn the heap over with a fork every few weeks to mix everything up, so the stuff on the top of the heap ends up on the bottom. This can speed up decomposition, but if you've combined the ingredients well in the first place it's usually not necessary.

While you may get a few creepy crawlies in a healthy compost heap, and hopefully lots of worms, you shouldn't get anything that harms your plants later.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.