Growing Winter Tomatoes
To successfully produce tomatoes through the winter or at least get them established for an earlier crop in spring.
- Varieties intended for colder climates (see below).
- Creating a warmer micro-climate with grow tunnels, under glass and cold frames or fresh manure (see below).
- Find out when is the latest and earliest I can plant. Try various tomato breeds, each planted monthly.
- Indeterminate varieties that are known to yield over a longer period.
Cold climate tomato varieties
Short season, cold tolerant varieties such as Stupice, Siberia or Siberian are tomatoes usually grown in the short spring/summer of the northern hemisphere and may produce OK in a warm/temperate Winter but should be planted out as early as possible (seedlings in march) from seeds sown in Jan.
Quick croppers like the Siberians should be ready to harvest in late November if seedlings are planted out in early August although they may need to be germinated inside, possibly with added warmth.
Purple Russian wilts in hot sun. It is possibly a candidate.
Creating a micro-climate
Tomato seeds germinate best at 20C . Tomato plants grow best at no less than 20C. Using the methods below you can plant seeds in Winter for planting out early spring and you should have tomatoes by late spring.
Raising winter seedlings with composting heat
You will need:
- Styrofoam box (retains heat). Scrubbed clean and sterilised. Drainage holes poked in the bottom.
- Glass pane to fit top of box to let heat and light in and to be removed if temperature inside exceeds 30 degrees.
- Grass clippings or fresh manure (generates heat whilst decomposing)
- Compost with a little slow release fertiliser and lime mixed in or cow manure.
In late winter, place 1-2cm of fresh grass in the styrofoam box. Cover with 5-10cm layer of compost mix. Plant seeds into the damp compost. Cover with glass pane.
Direct sowing above fresh manure
Lay 20-30cm of fresh manure in trenches. Sow seeds into topsoil placed on top. Heat will radiate upwards warming the soil. Mulch on top will help retain heat generated.
More info, see the book ‘Tomatoes for Everyone, A practical guide to growing tomatoes all year’ by Allen Gilbert.
Experiment 1: 28/4/15
Desired outcome: If I can grow a healthy plant, it should start fruiting in August (a few months before other tomatoes).
Planted: Siberian seed
Position 1: Indoors on window sill in pot of coir. 28/4/15. Germinated 3/5/15. Placing outside on warm, sunny days. Used old soil raising mix and it did not do well. Have dumped it.
Position 2: Outdoor in garden (veg bed 6 and front bed 5). Took 1 week longer to germinate than those on window sill. Looks healthy, but slow growing.
Climate: Still relatively warm at time of sowing with max day temperatures predicted to be Max 20C. However, periods of severe rain and wind and minimum sunny days may affect growth after germination.