Late Cropping or ("Christmas Cropping") Potatoes

Late cropping seed potatoes are harvested in October and kept in cold store (4 degrees centigrade) from December through to June and July. When brought out into the high summer temperatures they start to grow immediately and should be planted as soon as possible.

Daylight hours decrease and temperatures begin to drop as the summer draws to an end leaving only a short time for the potatoes to grow and produce the new crop. Later planting will reduce the growing period and so the yield also the seed potato’s natural time clock is ticking and if left too late in the season may just not grow.

The risk of a blight attack at this time of year is high when temperatures are still warm and there is plenty of heavy rain to spread the spores..

The term, Christmas potatoes, is perhaps misleading as most of the growth has happened and new tubers formed by the end of October. The newly formed immature potatoes can best keep their freshness by chopping off the tops and leaving in the soil making sure the area is dry, pest and frost free.  Success will depend on where in the UK they are grown, whether under polythene or outside, disease pressures and of course your skill. Small thinly skinned steamed or boiled potatoes with parsley can be a great accompaniment to maincrop roast potatoes on a full Christmas spread which will satisfy all palates.

Growing Tips & Guide

General

Late Cropping potatoes can be produced in your own garden by planting specially prepared seed potatoes during late June / early July. The seed potatoes have been kept in environmentally controlled stores which slow the growth of the potato by holding at low temperature (4°c). No chemicals are used.

Arrival

The seed potatoes start to grow immediately as they enter the warm air after leaving the cold store. It is important to plant as soon after receipt as possible as they will grow rapidly.

Planting

Select a patch of ground, ideally keeping to a minimum 4 year rotation. This is not always possible in the vegetable plot as space is very limited. Some gardeners have achieved success in planting a second crop after the removal of the first crop of Earlies.

• Broadcast a potato fertiliser, according to manufactures instructions, over the forked ground.
• Plant in rows 25-30 inches apart with 12 inches along the rows between the potatoes.
• Dibble in or cover so there are 5 inches of soil above the potato. Water if conditions are dry.

Growing

As soon as the plants begin to emerge; start earthing-up by pulling soil over the rows. This will keep the weeds at bay, until canopy closure is effective and will ensure the potatoes are fully covered by soil, as they will go green if not (green potatoes should not be eaten).  During the end of the normal growing season plants are more prone to attack from pests and diseases, in particular blight and slugs. Biological or chemical control should be considered.

Harvest

Into October there is the danger of an early frost so a cloche or fleece will give some protection. Cut the haulm just above the ground during October (to limit disease risk and prevent crop growing too large). Extra earth or straw/fleece will improve frost protection. Leave in the ground until required, but  ideally no later than early January.

Growing in Containers

This is ideal as the plants can be started outside and then moved into the greenhouse when room permits at a time when the average temperatures are dropping. This will extend the growing season and increase yields.  See Growing In Containers for further information.

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