Pee for the Peonies
Our UM team will be in and around the garden, beds 24-27, on Saturday June 7 and Sunday June 8, 2025, from 9 - 10:30 am each day.
We will be available to talk about our work with urine recycling that creates a collection of pasteurized, nutrient rich, licensed fertilizer products. We will have some urine-derived struvite handouts for the first 100 visitors.
For those interested in urine recycling for their gardens, learn more from the Urine My Garden program developed by the Rich Earth Institute. Import fewer virgin fertilizers; recycle more from your own household!
In 2021 and 2022, we applied a treated, sanitized urine-derived fertilizer (UDF) from Brattleboro, VT to peony beds 24 & 26 (control beds: 25 & 27). Nutrients were applied in accordance with soil tests. In 2023 we did not fertilize. In 2024, we fertilized with UDF from our urine separation system on U-M’s north campus and created a 0.2 : 0.4 : 0.4 NPK product. We applied to one of two peony pairs in all four beds (24, 25, 26, 27). In 2025, we continued by applying fertilizer to one of two peony pairs but made a stronger NPK product with ratio 1.2 : 2.3 : 2.3. The changes in NPK ratio come about as we have upgraded our processing equipment and learned how to concentrate more efficient.
While the fertilizer needs for peonies are modest, our primary goal is to direct attention to how nutrients flow through our community, regenerative food-nutrient cycles, and how urine recycling can be part of a more sustainable future.
“Pee for the Peonies” is a partnership between University of Michigan researchers in the department of Civil and Environmental Engineering and the Matthaei Botanical Gardens and Nichols Arboretum.
Fertilizing the Peonies
Kristina Bonnet applies U-M’s sanitized urine-derived fertilizer (UDF) to sprouting peonies in April 2025.
Water (2 left containers) and concentrated UDF (right container) are carried into the garden. We dilute the concentrated UDF to the desired ratio, then apply by pouring around each plant’s dripline.
Professors Rachel O’Brien (left) and Nancy Love (right) combine water and UDF concentrate to make solutions to apply to the peonies.
