Determinate vs Indeterminate — Know Your Variety

Pruning depends entirely on which type of tomato you are growing:

  • Indeterminate (cordon) tomatoes: Keep growing and fruiting all season until frost. Varieties like Grosse Lisse, Beefsteak, Cherry tomatoes. These benefit significantly from pruning — without it they become unmanageably large, produce many small fruit and are prone to disease.
  • Determinate (bush) tomatoes: Grow to a set height, produce all their fruit in a concentrated period, then stop. Varieties like Roma, Tigerella, most paste tomatoes. Require minimal pruning — excessive pruning reduces yield.

If you are unsure which you have, check the seed packet or plant label. Cherry tomatoes and most heirloom varieties are indeterminate.

Pruning Indeterminate Tomatoes

  1. 1

    Remove suckers while small

    Suckers are shoots that grow in the V-shaped junction (axil) between the main stem and a branch. If left, each sucker becomes a full stem, the plant becomes a large uncontrolled bush, and energy is divided between many small fruit. Remove suckers when they are 1–5cm long — simply pinch or snap them off with clean fingers. Larger suckers (over 5cm) are better cut with clean secateurs to avoid tearing the stem.

  2. 2

    Choose 1 or 2 main stems and train them up support

    Single stem training (removing all suckers) gives the largest individual fruit. Two stems (keeping one sucker near the base to become a second main stem) balances fruit size and total yield. Tie the main stems to stakes or cages as they grow.

  3. 3

    Remove leaves touching the soil

    Lower leaves that touch or are near the soil surface carry soil-borne diseases onto the plant. Remove any leaves below the lowest fruit cluster, keeping the bottom 20–30cm of stem clear.

  4. 4

    Top the plant in late summer

    In late summer (February in Australia), pinch out the growing tip (the topmost growing point). This stops the plant putting energy into new growth and directs it into ripening existing fruit before the season ends.

When to prunePrune in the morning on a dry day. Morning pruning allows any wounds to dry before evening humidity. Clean secateurs between plants with disinfectant spray to prevent spreading disease. Do not prune in wet conditions — moisture in the cuts promotes fungal infection.

Frequently Asked Questions

Pruning increases the size of individual fruit and improves air circulation (reducing disease), but may reduce the total number of fruit compared to an unpruned plant. The trade-off: fewer, larger, healthier fruit vs more but smaller fruit with higher disease risk. For home gardens where quality matters over maximum quantity, pruning is usually beneficial for indeterminate varieties.
Yes — yellow lower leaves are normal as the plant ages and directs energy upward. Remove them cleanly with secateurs rather than pulling, which can tear bark and create entry points for disease. If yellowing is spreading rapidly up the plant or the leaves have dark spots, this may indicate a disease (early blight, septoria leaf spot) — remove affected leaves and consider a copper-based fungicide spray.