Top Dressing Clay Flower Beds With Biosolids - April 2026

The pizza oven beds that I created last year are sitting on top of one of our large drywells.  The natural soil in this area was dug up, a huge pit of gravel was installed and then the builder backfilled the top with what appears to be a lot of clay soil.  That means that the area isn't great for gardening.  Starting last year, I have begun to amend the soil in an attempt to grow more things in this area.  Last week, I posted about how I was burning some leaf litter in-place in this bed.  My thinking was that adding this ash to the bed can amend the clay as it works its way down through the layers.  

This year, ahead of planting this bed up, I went and grabbed some municipal biosolids and dumped about 20 gallons on both sides of the pizza oven bed.  Below are some photos showing the biosolids on top of the existing mulch.  You can see the darker color in contrast to what was there in-place. 

My plan is to use the west-side to plant perennials.  That's #3 and #4 on my 2026 to-do list.  But, on the east-side of this bed (the second photo), I'm going to try to plant more dahlias.  

For now, I left the biosolids on top, but I'll work it in as I plant things up.  If I find the time, I'd like to try some vertical mulching in this bed like I did in our front porch bed a few years back.