Production need never stop in the greenhouse

A Garden Club member was enquiring about greenhouses, a subject with so many variables.

Saturday, 19th May 2018, 12:38 pm
The propagator is buzzing with germinating seedlings and chrysanthemum cuttings. Picture by Tom Pattinson.

Size, type, cost, circumstances, siting, aspirations are just part of it. Then there’s the age-old advice about deciding what size you want and how much you can afford, then doubling both figures.

An unheated greenhouse is the engine room of this garden. It’s used for tender plant storage and the cultivation of edible and ornamental types. Three main crops are grown in succession over a year in the main border – salad lettuce over winter, tomatoes from May, and chrysanthemums in autumn.

There is permanent staging for general display, a propagating facility, and an inner door leads to the potting bench. Many plants pass through here in a gardening year, but there are two fruit-producing residents, a peach and grapevines.

In the absence of artificial heat, balancing a greenhouse environment does present difficulties, but these can be overcome, turning it into a productive year-round unit.

Between March and April, the maximum/minimum thermometer, a must-have piece of equipment, recorded two extremes; minus 4C and plus 25C. One called for protective fleece over vulnerable plants, the other for opening of ventilators and door, plus damping of floor.

From late February the greenhouse becomes a powerhouse for propagation and crop growing. A normal, mild winter heralds pink flowers on the peach tree as March approaches, then bud-break comes on the grape vines.

And as we enter April the only extravagance, a square-metre propagating box, is buzzing with germinating seedlings and chrysanthemum cuttings. It is fitted with a soil-warming cable that is switched on from February until April, giving a boost to the raising of vegetables and ornamental plants.

We are presently running out of bench space, trays of pricked-out seedlings competing with potted-up rooted cuttings, plant plugs and vegetables.

In a week or so it will be the tomato plants’ turn to stand in the border presently occupied by a lingering winter leaf-lettuce crop that has remained sweet thanks to regular watering. It’s nigh impossible to cultivate lettuce without a slug presence, but we have two toads that help in that respect.

Once the lettuce is cleared, the border receives a dressing of general organic fertiliser in preparation for tomato plants that stand in large pots of fresh compost.

Regular watering encourages roots to extend into compost and border soil. Their presence in pot and border creates a possible buffer against root disease.