Blossom End Rot

Blossom end rot is the sunken brown patch at the base of tomatoes, peppers and courgettes. It happens when calcium does not reach the developing fruit in time, usually because of uneven watering rather than a shortage of calcium in the soil. The fix is steady watering plus a calcium feed to support supply. Which calcium feed depends on what you need:

  • Liquid Gypsum: best once symptoms appear. Fast-acting calcium that does not raise soil pH, so it is the first choice for quick correction.
  • Liquid Cal-Phos: calcium with extra phosphorus. Choose this if you also want a phosphorus boost alongside the calcium.
  • Calcium Carbonate: calcium that also raises pH. Use where your soil is acidic and you want to lift pH at the same time.
  • Micronised Rock Phosphate: slow-release calcium and phosphorus. A long-term soil source rather than a quick fix.
  • Cal-Mag: prevention. A balanced calcium and magnesium feed that keeps levels topped up so the deficiency is less likely to arise.

Even watering does most of the work; the right calcium feed covers the rest.