Are these slug eggs in my compost?

You’ve opened a new bag of compost ready to get potting and suddenly see little white balls. But what are they? Surely not an infestation of fresh slug eggs?


What are the tiny balls in the compost?


You may have noticed small white balls in the compost when using it. We use a controlled release fertiliser for long term nutrients These are small white/beige balls approx. 3mm in diameter and are mixed into the media.

Compost balls vs Slug eggs

(Left) Controlled release fertilizer granules || (Right) Slug Eggs



Why do we add them to your compost?


We made this addition to our recipe in the autumn of 2021 to improve the shelf life of our growing media. The nature of this controlled release fertiliser is that it will slowly release the nutrition and become softer as the compost is stored. As the fertiliser becomes softer the hard white balls become transparent as the nutrition inside moves out in the media.


How we know they’re not eggs


They are highly unlikely to have been in the bags of SylvaGrow® at the time of packing. Firstly there is nothing in our ingredients to attract slugs or snails. Secondly, even if eggs were present, the processing that our materials are subjected to is too disruptive and the temperatures in our composting piles of wood fibre and bark are too high for eggs to survive.


So what are the differences?


Controlled release fertiliser balls:

  • Have a hard coating that cracks when crushed between the fingers.
  • Individual beads will be well distributed through the compost.

Snail and slug eggs:

  • Wet and slippery
  • Do not have a hard shell
  • Are laid in clutches of many eggs

Vine weevil eggs:

  • Smaller than beads or slug and snail eggs
  • Less than 1 mm in diameter and brown in colour
  • Difficult to spot with the naked eye

So you can rest assured that using SylvaGrow® is not going to cause unwanted pests in your garden.