AN OUTLINE OF CUCUMBER CULTIVATION

Cucumbers were mainly grown in low, narrow houses up to 4.5m in width, but many commercial growers now use VENLO multispans or the 9m wide aluminium vinery type houses.

Varieties

Several F1 hybrids are now grown eg Green Spot (this being similar to BDR), Top Score and Feminex, which has 100% female flowers. BDR is still grown and Telegraph is popular for amateur gardeners, especially in cool houses.

Propagation – Main crop

Propagation is often from mid-December onwards, however on commercial nurseries specialising in cucumbers sowing dates often commence in late September, as follows if sowing in batches for a successional cropping programme.

Sowing dates Propagation period Harvest date commences

September – October 8 weeks February

January – February 5 weeks mid March

March – May 4 weeks 7 weeks after sowing

Two weeks can be deducted from sowings made in the period October to March by using supplementary lighting. Germination takes 40 – 48 hours at 27°C. 90mm size pots are half filled with J.I. Potting Compost No. 1 or loamless seed mix and one seed is sown per pot. Later when the young plants have grown well clear of the pot rim, the pot is topped up, using J.I.P. No. 2 or loamless potting mix. Propagate at 20 – 22°C and after germination lower the temperature to 18°C. Plants should be staked and spaced 300mm – 600mm apart, preferably in an east/west propagating house, or in good light conditions, soil-less composts are much more often used than J.I. composts but the growing technology thereafter requires either more liquid feeding or the use of slow release fertilisers.

Bed preparation

The bed should not be too large, approximately 450mm wide at the base, and 400mm deep is suitable, and it should be open and well aerated. The Layer Bed, as the name suggests, consists of alternate layers of wheat straw, horse manure (well rotted) and steamed loam, each layer being approximately 100 – 150mm thick.

Feeding

One or two high nitrogen feeds may be given in March-April to established plants but avoid over soft growth. Keep plants well spaced out.

Staking

375mm thick green canes are used, usually one to each main shoot. Regular tying in of shoots is essential to prevent straggly growth, some cultivars being worse than others in this respect. Where plants are potted on to 125mm pots, use 500mm canes.

Varieties

It is usual to grow two or three different colours so that boxes of mixed colours can be marketed.

Galilee pink double flowers. Variegated leaves – Crocodile

Mdme Crousse pink, veined maroon. Striped flowers – Bacaraat

Scarlet Crousse

La France lavender

Crocodile variegated leaves

Bacaraat striped flowers

Cultivars with striped petals (red and white) have become very popular. This striped effect is achieved by inoculation with a virus. The same infection on the usual geraniums does not produce such an attractive effect. Normal propagation by cuttings maintain the stock and there are no other serious signs of deterioration from the infection.

Pests

White fly can be troublesome and regular fumigation with HCH may be needed. Resmethrin may be used. White oil emulsions are also effective.

Other troubles

A thickening of the under surface of the leaves called oedema, due to overwatering, is not uncommon. This condition may be made worse when plants are grown on capillary benches. (It may also come about from the use of white oil emulsions which are too thick with oil.)

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