Are commercial potting mixes suitable for roses?
Written by
Liu Xiaohui
Reviewed by
Prof. Charles Hartman, Ph.D.Many rose growers are disappointed by commercial potting mixes. They are easy to use, but they do not have the necessary drainage or nutrient ratios required to grow roses. I have seen commercially bought mixes suffocate the roots within weeks. I have had better results by mixing 50% loam soil, 30% perlite, and 20% compost. This mixture emulates their natural habitat.
Loam Soil
- 50% base for structure and nutrients
- Provides calcium and magnesium
- Supports mycorrhizal fungi networks
Perlite
- 30% aeration to prevent compaction
- Creates air pockets for root respiration
- Doesn't break down over time
Mixes based on peat are notorious for this problem. A client in Seattle lost six roses to root rot before I converted her to a mix loaded with perlite. Peat acts like a sponge: excellent for ferns, terrible for roses. Just make sure to monitor the peat content on the label, and if it exceeds 20%, don't buy it.
Summer Care
- Add 5% coconut coir for extra moisture
- Top-dress with worm castings monthly
- Elevate pots to improve airflow
Winter Prep
- Mix in 10% bark chips for insulation
- Reduce perlite to 25% for slower drainage
- Wrap pots in bubble foil below -1°C (30°F)
It is never a safe idea to reuse old potting mix without sterilizing. To properly sterilize the potting mix, you can bake it to 82°C (180°F) for about 30 minutes to kill pathogens. But an even safer thing to do is swap out 50% of the potting mix once a year. Your roses will thank you with deep-colored flowers and a little less pest-fighting for you to deal with. Trust this process.
Read the full article: Best Soil for Roses: Expert Tips for Lush Blooms
