How Much Compost is Enough?

PHS Digital Classroom

Calla Rose Ostrander is a partner in the Marin Carbon Project and a Strategic Advisor to individuals and organizations dedicated to the well-being of people and the planet. She brings the most up-to-date science on carbon sequestration in landscapes for the benefit of plants right into your front yard.

Our west coast native plant growers advise gardeners not to amend the soil when planting our local flora, yet the growing body of research into the importance of using compost to build healthy soil structure creates seemingly contradictory directives. The Marin Carbon Project has documented that applying compost to degraded soils (like soil in your front yard) sparks a microbial revolution that sequesters carbon, holds more water in dry times, and encourages the growth of native species. Calla Rose helps us think through the “Goldilocks Question” of how much compost is just right for our urban gardens.


This presentation is part of Pacific Horticulture’s FREE Digital Classroom online learning series to connect gardeners with some of the most intriguing horticultural and environmental issues of our time.

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This program was made possible thanks to the generous contributions of our donors and a supporting grant from the Pendleton & Elisabeth Carey Miller Charitable Foundation.