Whatever we grow by way of vegetables each year there’s always one that must be on the list – the tomato.
Whether it’s for a sandwich, salad or quick sweet snack as you inspect the greenhouse, there is such pleasure in picking the fruits fresh from the plant.
Gardeners who have heated greenhouses and enjoy the bragging rights that early crops bring, will have sown theirs last month and now concentrate on offering the full light and moderate warmth that encourages sturdy growth.
Meanwhile, those of us without heat contemplate sowing at the end of February and nursing the young plants through a tricky period.
I have a home-made, timber propagating cabinet one metre square that stands in the greenhouse. It has a soil-warming cable and thermostatic control that will be brought into use next week. The seeds of tomatoes, other vegetables and several tender ornamental plants will pass through it, germinate and move on as March unfolds.
Just beyond the middle of next month, tomato seedlings will be ready for transfer to individual pots, and what happens next is rather a leap of faith but it works for me.
Far from being frozen all the time, even the cold greenhouse can overheat at the beginning of February. Mine has been over 20 Celsius just after midday and with the automatic vents open on more than one occasion already. And an acquaintance related last week how he’d been in one that was recording 32 Celsius with solar heat alone.
By the simple action of closing vents slightly earlier in the afternoon you can arrest the warmth at its peak and build up a head of steam that will last well into any frosty night.
As an extra precaution I always have rolls of protective fleece standing by.
Even young tomato plants, which do not take kindly to cold nights, emerge safely from under cover without a hint of blue on their leaves. Placing them well away from the glass, even on the floor in the centre of the greenhouse when very low temperatures are forecast, is also part of the strategy for them and seedlings of ornamental plants.
The simple alternative is to purchase young potted plants at a later date as they appear on the garden centre shelves. Granted this is more expensive than the single packet of seeds that produces more plants than you could ever grow, but it eliminates the early concerns of balancing temperature, light and watering.
When you’re buying plants, select those that have healthy green leaves and sturdy growth. If they’ve been grown well, the two original seed leaves (cotyledons) should still be intact on the stem just above compost level.
Avoid those with many roots coming through drainage holes at the base as this betrays a pot-bound state. My young tomato plants are transferred to slightly larger containers just as the basal roots begin to form a circle.