Here are some causes or reasons why the stems on your roses have broken… There are numerous reasons and if you are unsure what is happening with your roses, please call me and if you are in the Perth area, I will organise a time to come and see you and your roses.
Weak or Thin Stems
- Lack of sufficient sunlight causes spindly, fragile stems unable to support blooms.
- Some rose varieties naturally have weaker stems that require pruning and thinning.
Water Stress
- Over-watering can make stems waterlogged and fragile.
- Under-watering leads to dehydration, making stems brittle and prone to snapping.
Nutrient Deficiencies
- Calcium deficiency weakens stems, causing brittleness.
- Lack of potassium and phosphorus affects overall stem strength and plant vigor.
Fungal Diseases
- Canker-causing fungi (e.g., Botryosphaeria, Leptosphaeria, Coniothyrium) enter through wounds and cause stem dieback.
- Botrytis cinerea (grey mold) thrives in damp conditions, causing stem cankers and collapse.
- Diseases are more likely to infect stems damaged by pruning or weather.
Improper Pruning
- Using blunt tools crushes stems, allowing infections.
- Cutting too far above buds or leaving long stubs leads to dieback from wounds.
- Proper pruning technique involves sharp tools and angled cuts just above healthy buds.
Physical and Environmental Damage
- Wind, storms, and frost can physically break or damage stems.
- Frost injury kills stem tissue, causing brittleness and dieback.
Pests
- Borers tunnel inside stems, disrupting nutrient flow and weakening stems.
- Thrips including Chilli Thrip and other pests damage young stems and flowers, contributing to weakness.
Planting and Soil Conditions
- Planting roses with graft unions buried too deeply increases dieback risk.
- Overly wet or dry soil conditions stress plants, making stems prone to breakage.
Each of these factors can contribute alone or in combination to rose stem breakage. Managing them through proper rose care—including good sunlight exposure, balanced watering and feeding, optimal pruning, pest control, disease prevention, and protecting from weather—helps maintain strong, resilient rose stems for beautiful, healthy plants year-round. If you need help with caring for your roses, I can create a care plan specifically for your roses to help them thrive.
If they look like they have issues, I will tell you there are problems and come up with a solution for you, if possible.
John Kelly