Tomatoes forming, 27 May 2020.

Types of tomato include ‘F hybrid’, ‘open pollinated’ or ‘heirloom.’

Gardeners can save seed from their own open pollinated (but not hybrid) crops.

There are two main forms of growing habit – determinate or indeterminate.

  • Determinate tomatoes have bushy growth and don’t need support or pinching out.
  • Indeterminate tomatoes – also known as vine or ‘cordon’ types – have a long main stem that need to be supported by a cane.  Regularly pinch out side-shoots.

Growing Tomatoes from Seed: Sow seeds under cover from late January to late March. Keep seedlings at around 18°C. Repot to a 3½ inch pot once the seedlings set their first true leaves, planting ¼ inch below the height of the seed leaves.  Plant out when 8 inches tall, with flowers opening.  You can also propagate new plants from branch cuttings of started plants to increase crop size.

Growing Conditions: Tomatoes love heat, so they do well with their soil covered in black plastic to retain moisture and enhance soil heat.  Ideal sites are flat, south-facing and protected from strong winds.  Don’t plant out until all risk of late spring frost has passed. 

Tomatoes need soil temperatures of at least 12°C to grow well as they cannot absorb phosphorus from the soil at low temperatures, resulting in purplish foliage, stunted growth and a poor crop. (RHS, The Garden, June 2019, p.22)

When planting out select a full-sun location, space plants 18-24 inches apart, planting them 1-2 inches deeper than in their previous containers.  The buried stems will produce more roots which will help secure the plant from rocking in the wind.

Situate your tomato plants into a sunny, sheltered plot at the start of June, after hardening-off.  Water regularly and feed fortnightly with a liquid tomato food (high-potassium) once the first truss of flowers opens.

Cordon tomatoes can grow up to 6 feet tall and need support.  On cordons, regularly pinch-out side-shoots just over 1 inch long.  (These can be potted to create new tomato plants if you want to expand your crop.)

Plant tomato with companion plantings of garlic, basil and nasturtiums.

Plant Diary: In 2020 we have two ‘Tumbling Tom Yellow‘ – both planted into containers.  These are a cascading, branching plant which bears sweet and delicious yellow fruit that are ideal for salads.  The even, branching habit of this tomato variety makes it ideal for ornamental container use.  The RHS (March 2020) state that Tumbling Tom are “compact.. with a delicious, slightly sharp taste.”

We also have a couple of Beefsteak tomato plants.  All tomatoes had been hardened off during the day and then planted out by the end of May 2020.  It was a particularly warm and dry spring, with a late May cold snap which thankfully didn’t damage the plants.  It is safer to plant out your tomatoes in early June when all risk of late spring frosts have passed.

For a review of tomato cultivars see RHS’s The Garden, March 2020 and The Garden, July 2014.