Hartley Magazine

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Important tips for growing crops in greenhouses


A greenhouse of foliage and flowering plants is easy to tend. Naturally you water, feed occasionally, maybe dead-head and sometimes propagate. It’s important to open and close ventilation unless you have an automatic set-up. And to keep watch for pests or diseases, and then take action. The care required is not huge however it increases significantly as you start growing crops.

Most crops bulk up and mature very rapidly with softer more succulent tissues than many ornamental subjects. Thus they need more attention to the routines mentioned above, and also to harvesting as soon as they become ready! So here are key points to consider.

Watering is crucial as 80-90% of most crops is water, any shortage, even for a short period, will give poor results. It’s difficult to ensure water soaks into partly dried out compost by watering from above, the top will look wet, water may come out the bottom while in between remains arid. Instead stand your pots half deep in bowls or big containers of, preferably warm, water. After half an hour simply lift them out and drain.

Feeding is also crucial, initial fertility in compost is soon consumed by hungry crops, adding feed to their water regularly replenishes this. All soluble liquid and powdered feeds must be really well diluted for safety so make these up according to instructions on the packaging!


Ventilation is more important than with ornamentals as faster growth with crops needs the air to change more often or they run out of CO2. If it’s cold and the greenhouse is better closed up stand something fermenting inside, not necessarily home brew, just sugar and yeast in a bottle of water will serve.

Now we come to pests and diseases, luckily the latter are not common if care is given to growing conditions, but some pests are continual harassments as these love our crops as much as we! SO watch for aphids, if these appear either jet/wash them off, or use a soft soap spray (not on hot bright days). Red spider mite cause tiny pin pricks and general yellowing, again wash or jet and soft soap sprays, and ideally purchase their commercial predator (Google for suppliers). And if holes in leaves, or worse the fruits, appear go out at night with a torch and hand pick the little devils. Job done.