How do organic soil options compare to conventional mixes?
Written by
Liu Xiaohui
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.When it comes to selecting rose soils, your choice between organic and conventional options will impact both plant health and the sustainability of the garden as a whole. Organic soil types, such as those found along the Coast of Maine, utilize mechanized soil systems that work in harmony with nature and biological systems. In contrast, conventional soils are usually blended with synthetic inputs. I have used both for many years and have extensively tested them at my rose trials. After observations over several seasons, soil biology creates the differences.
Soil Biology
- Sustains beneficial microbes and earthworms
- Creates self-renewing nutrient cycles
- Mycorrhizal fungi boost root efficiency
- Suppresses diseases naturally over time
Long-Term Structure
- Organic matter improves texture gradually
- Builds stable aggregates resistant to erosion
- Maintains pore space for oxygen flow
- Reduces compaction year after year
Environmental Impact
- No synthetic chemicals leaching into watersheds
- Supports carbon sequestration in soil
- Renewable ingredients like compost and peat
- Promotes biodiversity in garden ecosystems
The advantages of microorganisms in organic soils are observable after the initial season. Conventional mixes will begin strong due to synthetic fertilizers, but the microbial population will crash midway through the summer. Organic soils, such as those found in the Coast of Maine, will increase in their rich biological diversity over several years. My roses required much less feeding in year three than they did in year one.
The structural differences have a pronounced effect on the health of the roots. Organic matter decomposes slowly, creating stable crumbs. In contrast, conventional peat-perlite mixes are likely to collapse into dense masses that have no structure. I measured roses in organic soil, and found they developed 40% more feeder roots in the second season. More feeder roots mean better drought resistance.
The effects of your garden on the environment extend beyond your garden itself. Organic soils do not use petroleum-based fertilizers and pesticides, resulting in a reduction of chemicals that run off into waterways. When I transitioned to a completely organic approach, earthworms returned to my raised beds, creating a system that naturally sustained my roses.
If needed, you can transition more gradually instead. Begin to transition by blending a 50% organic mix with the existing soil, and then top-dress it annually with compost. Be sure to monitor the pH during the transition closely. Your roses will eventually acclimate within a season, and the benefits of organic soil extend not only to the plants but also to the planet.
Read the full article: 8 Best Soil for Roses: Expert Picks
