Here’s a useful guide for anyone who is growing potatoes this season. We cover when to harvest, how to store them, any potential problems as well as which crops to plant after you’ve harvested.
When to Harvest Potatoes
Earlies are usually ready for harvesting as soon as the flowers start to form. First earlies will flower earlier than second earlies. To check, carefully scrabble away into the soil until you find a couple of potatoes with your hands. If they are about the right size, then they are ready for harvesting, if they’re still too small, leave them another fortnight or so.
Maincrops are, as a general rule, harvested towards the end of August. For these, you want to wait for the leaves to start turning yellow before harvesting. Again, check to see that they are the right size before you start harvesting.
If the soil is loose enough, you should be able to harvest without using a fork which will mean less damage to the potatoes. If you do need to loosen the soil with a fork, try and give the plants a wide berth and go deep to avoid spearing them!
You don’t need to harvest all your plants at once. If they are getting a bit big, you can cut off the foliage and your potatoes will stop growing but will keep in the ground for a few weeks (for earlies) or a month or two (main crop).
The only risk with this is pests eating away at them – wire worm are the most likely offenders, also slugs. If you’re worried about this, you can harvest them all at once and put them into a hessian sack, unwashed. Keep them in a cool, dry, dark and airy place and they’ll keep well for a month or so.
Problems with Potatoes
Disintegrate on cooking – if the potatoes have not had enough water whilst growing, you may find they turn to mush on cooking. One way around this is to steam the potatoes, or roast without par-boiling first. Next time, be sure to water more consistently.
Potato Scab – This bacteria-driven disease causes “scabby” rough patches on the skin of potato tubers and often occurs in hot, dry summers. It can be avoided by watering regularly and thoroughly. It’s not a major problem and you can scrape or peel the tubers before cooking to enjoy your crop anyway.
Blight or Black leg – f blight is a problem, you probably will have seen evidence of the disease on foliage before digging up the tubers, but you may find that some of the tubers have started to rot. If you see stems turning black on your potatoes then it is likely to be black leg, a bacterial disease that strikes during damp weather. It’s easily confused with blight as the leaves start to turn yellow as well. Look for leaf curling and lack of brown spots to distinguish it from blight.
Slugs – Yep, sadly slugs will have a good old munch through your potatoes without you even realising they’ve done it until you dig them up! Try to keep on top of slugs by setting beer traps etc, and if you have a slug-infested garden then dig the potatoes up as soon as they are ready rather than leaving them in the ground.
Following On With Other Plants
Once you’ve harvested potatoes, you can plant up again straight away. Usually the soil is nice and loose, and this makes it great for planting up some leek seedlings which will grow into autumn and give you a good crop to enjoy over the colder months. Alternatively, firm the soil back down again and plant up a whole host of brassicas – kale, cabbages, cauliflower etc, to keep you going. They will do well from being planted in July, and should be harvestable around Christmas time.