How to Grow Second Crop Autumn Potatoes for Christmas

Second cropping potatoes are one of the most rewarding crops you can grow. Fresh new potatoes with your Christmas dinner from your own plot, harvested the same day are quite honestly unbeatable

When to Plant Autumn Potatoes

Timing is pretty critical to success with autumn potatoes. The ideal time for planting is late August and plantings after the first week of September are unlikely to provide that magic Christmas crop. So you need to obtain your seed potatoes in good time. Ideally you want to have them by early August and start chitting with a view to planting at the end of the month although you don't actually need any chitting time if they arrive late.

Suitable Second Crop Potato Varieties

Most early and second early varieties are suitable potato varieties for late growing, but the easiest and most popular variety is Carlingford. Charlotte, which is a waxy salad potato is another good one to grow. You can eat them as new potatoes with Christmas lunch and turn the leftovers into a potato salad to accompany a cold buffet. Maris Peer, not to be confused with Maris Piper, are another popular Christmas potato.

The autumn planting seed potatoes are not specially bred variants of the ordinary types. They are exactly the same tubers but the merchants have carefully stored the seed potatoes in climate-controlled, optimum conditions, which is a service you pay for. However, you can store your own spring seed tubers for autumn planting.

Just chit as usual and leave in the chitting tray through the summer. Remember they need light, but not direct, strong sunlight and to be kept cool. Keeping them cool is the difficult part. I find a monthly spray with a seaweed solution helps develop strong shoots but it's not strictly necessary. Our north-facing garage is the coldest place and only has dim light through the windows in the door. The shed would be ideal except it can get quite hot in summer which would over-stimulate and dry out the tubers.

Planting Out Autumn Potatoes

You can plant out your second crop potatoes just as you do your first crop. The soil should be nice and warm at this time of year and they'll get off to a good start so long as you ensure they have enough water.

Don't plant in the same place as you planted your normal crop of potatoes if you can avoid it. If you can't avoid that then you must use a balanced potato fertiliser or feed with loads of comfrey liquid feed as the nutrients in the soil will have been depleted. A potato fertiliser is a good idea wherever you plant out anyway, potatoes are a greedy crop. Also avoid areas recently limed, potatoes are unusual in the vegetable world as they actually like a slightly acid soil – pH around 5.5 is ideal.

Another way to grow, and possibly a better way, is to grow your late potatoes in bags. Fill the bags with a good quality multi-purpose compost to which you've added some potato fertiliser. Work on the recommended application rate per square metre per bag. The advantages to bag-growing are two fold. Firstly, the potato skins will be unmarked and look attractive. Secondly the whole bag can be moved into a greenhouse if the weather should get really bad.

Problems with Late Crop Potatoes

The main problems with late planted potatoes are frost and blight. Frost will kill the haulm (as we call the foliage) so tubers cannot develop. Covering with fleece will protect against a light frost but if it gets really cold then you may need to double up on fleece. Supporting the fleece in some way to form a tent so it doesn't touch the foliage is helpful in this situation.

Blight can be a problem even through to November although September is usually the last danger month. You can use a spray but I prefer to rely on a fleece barrier for this. The spores are usually floating about in the air and washed onto the leaves by rain, so preventing them getting to the plants stops blight from taking hold.