Lesson 5
Pruning, staking, and training
Indeterminate tomatoes (most heirlooms, San Marzano Lungo) grow as single-stemmed vines that continue upward until frost. Pinch out side shoots (the small shoots that emerge between the main stem and a leaf) weekly — they divert energy from fruit. Leave the main stem and the flowering trusses. Stop the plant at 1.5–1.8m by pinching out the growing tip in late August; this diverts energy into ripening existing fruit rather than making new flowers that won't mature.
Determinate tomatoes (Roma VF, some dwarf paste types) grow as self-supporting bushes that stop naturally at 60–90cm. Do not remove side shoots — they carry the fruit. No stopping is needed. These types suit smaller pots and finish cropping earlier, usually by mid-September.
Stake indeterminate types at planting. Use a 1.5m cane or a spiral support. Tie the main stem loosely every 20–30cm as it grows, using soft string or plant ties. Heirloom beefsteaks produce heavy fruit — support individual trusses with a sling of garden twine if stems bend sharply. Remove any leaves below the lowest ripening truss once fruit begins to colour; this improves air circulation and speeds ripening.
Quick reference — pruning by type
- Indeterminate (Brandywine, Black Krim, San Marzano Lungo): pinch out all side shoots weekly
- Determinate (Roma VF, bush types): leave all side shoots, no stopping needed
- If unsure: pinch out side shoots until mid-July, then reassess plant habit
Weekly pruning routine for indeterminate tomatoes
- 1.Inspect the plant from the base upward, looking for side shoots in every leaf joint.
- 2.Pinch out side shoots when they are 5–10cm long — they snap off cleanly.
- 3.Tie the main stem to the support if it has grown 20cm since the last tie.
- 4.Remove any yellowing or damaged lower leaves by pulling them downward sharply.
- 5.Check flowering trusses for weight — support heavy fruit clusters with twine if needed.
- 6.In late August, pinch out the growing tip two leaves above the topmost truss.
Prune in the morning on a dry day — wounds seal faster and disease is less likely.