Gardening glossary
Side dressing
Side dressing is mid-season fuel. You prepared the bed with compost and a balanced base fertiliser before planting, but heavy feeders like tomatoes, peppers, sweetcorn, brassicas, and squash burn through that initial supply long before harvest. Side dressing tops them up at the moments that matter — usually flowering and fruit set.
How to side dress:
1. **Pick the right product.** Granular fertilisers (blood, fish and bone; pelletised chicken manure; balanced NPK) suit slow-release feeding. Compost or worm castings work for a gentler boost. For a fast hit, switch to a liquid feed instead. 2. **Wait until the plant is established.** First side dressing usually happens 4–6 weeks after transplant, or when the plant starts flowering. 3. **Apply in a band, not against the stem.** Scatter the fertiliser in a ring about 10–15 cm away from the main stem, following the drip line where the feeder roots actually live. 4. **Scratch it in lightly** with a hand fork, then water well to start moving nutrients into the root zone.
Crop-by-crop guide:
- **Tomatoes:** side dress when the first fruits set, then every 3–4 weeks. Lean toward potassium and calcium over nitrogen once flowering begins. - **Sweetcorn:** side dress with nitrogen when plants are knee-high and again at tasselling. - **Brassicas:** nitrogen-rich side dressing 4 weeks after transplant, when the rosette is forming. - **Peppers and aubergines:** balanced feed at flowering, then potassium-heavy through fruiting. - **Leafy greens:** lighter nitrogen side dressing every 3 weeks while cutting.
Skip side dressing for legumes (they fix their own nitrogen) and for root crops like carrots and parsnips, where extra nitrogen causes hairy, forked roots. The point is precision — feeding the crops that ask for it, at the moment they ask, instead of dumping fertiliser blindly across the bed.