RHS Horticultural Advisor Caroline Mazzey shares how to start new potatoes in August to serve up during the festive season
Digging fresh spuds is almost magical for me – like finding buried treasure. The invisible multiplication of one potato into many seems too good to be true. Yet, year-on-year it reliably happens, and now I know that new potatoes aren’t just for summer!
August is the time to plant specially held-back seed potatoes so that they grow a second harvest for the later months. The crop will not get very big, and bakers aren’t going to happen, but a harvest of small new spuds in December brings back a taste of summer in an instant.
The seed potatoes sold for this purpose are often first earlies, as they only take around twelve weeks to be ready. Varieties such as ‘Duke of York’, ‘Pentland Javelin’ and ‘Arron Pilot’ are some of the most suited, but I also find the second early ‘Charlotte’ perfect. It depends what’s available at your local garden centre.
Planting potatoes in August, there’s no need to chit them – where you leave them in the light to sprout – because the soil is already warm. However, earthing them up is still the best way to increase the harvest and protect them from any early frosts. Plus, it stops any near the surface from turning green.
I plant the seed potatoes into holes made with a bulb planter, and water straight away to settle the soil around them. When I’ve finished the row, I mound up soil along the whole row, to form a ‘drill’. You can alternatively dig a trench about 10-15cm deep, place the seed potatoes in and back-fill it.
Don’t forget to mark the position of your potatoes clearly, as when the greenery has gone (as soon as temperatures drop) it can be tricky to find the row. One year, when we had snow, I couldn’t find my potatoes!
Another technique is to plant one seed potato into a 30 x 30cm (1ft x 1ft) container with drainage holes. This may suit you better if you want to grow your potatoes in a greenhouse or a sheltered corner – just make sure they get enough water (even in the ground, your potatoes will need watering to help them swell).
Fill the bottom of the container with a 10cm (4in) layer of soil, lay the potato on top, and cover with another 10cm of soil. As the potato shoots grow, add more soil, and keep going until the soil is at the top of the pot.
If you don’t have soil for your container growing, peat-free compost will be fine, and considerably lighter. You will need to feed them in this case, and a soluble fertiliser such as liquid seaweed, added when you water, will be ideal.
If, like me, you don’t manage to lift all your potatoes, don’t worry. Mine grew again the following spring, as if I’d just planted them, and I got the normal June crop from them.
Good luck! Read more about growing potatoes for the festive season here.
You may also be interested in
Look for the RHS Award of Garden Merit (AGM) when buying vegetable seed or small plants. You can also download the RHS lists of recommended cultivars.
About the author – Caroline Mazzey
Caroline is an RHS Horticultural Advisor based at Wisley, with allotments and a large family!
