Feeding Roses: When, What, and How Much
Roses are hungry plants. On the Peninsula’s sandy soil, where nutrients wash through quickly, regular feeding is the difference between a bush that survives and one that puts on a show. But it doesn’t need to be complicated.
When to Feed
The simple schedule: feed monthly from September through March. That’s seven feeds across the growing season. Stop feeding in April and don’t start again until you see new growth in spring.
Feeding outside this window — particularly in late autumn or winter — encourages soft new growth when the plant should be resting. That soft growth is vulnerable to cold and disease.
The September Kickoff
The first feed of the season is the most important. After winter pruning, your roses need fuel to push out strong new growth. In September, apply:
- A generous handful of complete organic fertiliser per bush
- A side-dressing of blood and bone
- A sprinkle of sulphate of potash (potash strengthens stems and improves flower colour)
Water everything in thoroughly. Follow up with a thick layer of compost and mulch.
Monthly Feeds (October–February)
Through the growing season, a monthly handful of organic rose fertiliser is enough. You don’t need to overthink this — any quality organic rose food from the garden centre does the job. Scatter it around the drip line (the outer edge of the bush, where rain drips off the leaves), not hard against the trunk.
Every second month, add a liquid seaweed drench. Seaweed isn’t a fertiliser exactly — it’s a tonic that improves root health, soil biology, and the plant’s ability to handle stress. Think of it as a multivitamin.
The Autumn Feed (March)
The last feed of the year should include potash to harden growth before winter and fuel the autumn flower flush. Many rose growers use banana skins buried around the base — they’re rich in potassium and break down quickly in sandy soil.
What About Manure?
Roses love well-rotted cow or horse manure. It’s an excellent soil conditioner and slow-release feed. Apply it in late winter (August) as a thick mulch layer around each bush after pruning. Don’t use fresh manure — it burns roots and can introduce weed seeds.
Chicken manure is strong and can be too nitrogen-heavy. If you use it, make sure it’s pelletised and well composted, and go easy — a light sprinkle rather than a heavy layer.
Signs of Nutrient Problems
Yellow leaves (overall) — usually nitrogen deficiency. Feed with blood and bone or a nitrogen-rich organic fertiliser.
Yellow between veins (interveinal chlorosis) — iron or magnesium deficiency, common in alkaline sandy soil. A dose of iron chelate or Epsom salts (magnesium sulphate) dissolved in water usually helps.
Poor flowering despite good leaf growth — too much nitrogen, not enough potassium. Back off the blood and bone and add more potash.
Weak, spindly growth — general underfeeding. The plant needs a complete fertiliser, not just one element.
The Peninsula Factor
Sandy soil is the key variable. Because nutrients leach through sand quickly, roses on the Peninsula need more frequent feeding than those in clay-heavy gardens. That monthly schedule isn’t optional here — it’s necessary. And building up organic matter in the soil through annual composting gradually improves nutrient retention, meaning your fertiliser works harder over time.
Think of it this way: in clay soil, fertiliser hangs around. In sandy soil, it’s gone by next watering. So feed little and often rather than dumping a huge amount once or twice a year.