Tanja is a greenhouse type of cucumber and is raised differently from an outdoor ridge type such as Marketmore.
It will need high temperature and high humidity. Germination can be erratic. Sow late February or early March in individual plugs in good quality seed compost. The temperature should be 25C degrees for germination, 21C degrees for growing the young plants on.
Keep young plants well watered, but not waterlogged, and keep the greenhouse humid yet ventilated. Feed plants once a week with a balanced organic fertiliser to maintain growth. Pot on to 23cm pots with a potting compost such as John Innes No. 3.
Support the plants by tying to bamboo canes. Take out the topmost growing shoot, when it reaches the roof of the glasshouse.
Greenhouse cucumbers are produced without pollination and male flowers must be removed immediately. These can easily be identified from the female flowers which have a tiny cucumber behind the petals.
The first cucumbers form in leaf axils on the main stem. Once these have developed, side shoots should be allowed to come out from the leaf axils and these will also produce cucmbers. Pinch the ends of these shoots off, leaving 2 leaves. Note that excess fruits will naturally drop off before developing.
Harvest from May onwards. Cut with a sharp knife. Tagetes (bedding-type French Marigolds) growing in pots around the greenhouse will help to deter whitefly.