I was told to put sponges in my full full sun flower boxes, I did I was cleaning the yard yesterday and went to empty out the flower boxes and the sponges were gone. Why did that happen? which type of sponge should I buy that will last the full summer? Thank you
Certified GKH Gardening Expert
I didn't find any research that said what kind to use, only that the cellulose lasted about a year. Those are made from wood pulp. Everyday common sponges are made from a type of plastic and other materials. The cellulose cost a bit more so you may not want to waste them in your potting soil.
You can always add vermiculite to aid in water retention.