How to protect Potatoes from frost
A common question this time of the year is how to protect Potatoes from frost.If young Potato plants are subjected to frost their foliage will be blackened. This will only kill the tops, and the plants will sprout again from underground, but that delays things and uses up energy reserves so is best avoided if possible.
Earthing-up the plants is best – draw soil over the leaves with a hoe (e.g. a Swan Neck hoe) making sure the leaves are completely covered with soil because then the frost won’t get to them. I only earth-up when frost is forecast, and then only “just enough” to cover the leaves, because it only takes a few days for the leaves to poke out again and there is only so much soil that can be piled over them, and thus only so-many-times that it can be done, to protect them. Alternatively cover with straw / grass clippings (but not if you have used selective weed killer or Weed & Feed on the lawn as the chemicals can persist in the grass clippings and then they will kill the Potatoes).
Fleece can be used for protection too, but it will only provide modest protection. Weigh the fleece down with stones / bricks etc. otherwise it will blow off the plants and leave them exposed to the frost. To my mind Fleece is second-best, compared to covering as above, because it will only protect against a modest frost; we can, and do, get -5C in May – albeit only once a decade or so – and even a double layer of fleece won’t keep that off. The roll of fleece I have is decent quality, and I’ve reused it again and again and it has lasted me for years. I’ve never tried the cheap material, but I read of a lot people saying how easily Fleece rips – so I presume they bought cheap and have a thin grade. Buy cheap = Pay twice!!
For years I went out at night to cover the Potatoes to protect them from frost. Not infrequently I would take the dogs out for their final pee before bedtime and only then realised how cold it was – resulting in me covering the Potatoes with fleece by torch light – quite a lot of cursing was involved!! Now I plant my Potatoes later (than I used to). I plant just a few at the early date, thus I only have a few to protect if we get a late frost, the rest go in later so the plants are later to emerge, and will be easier to protect if there is a really late frost. I try to plant just enough of the First Early varieties, really early, to provide for how many we will actually eat before the later ones are ready. For example, I bought just 4 seed tubers of Rocket (which I think is one of, if not “the”, quickest maturing variety), and I also planted 6 tubers of Arran Pilot, which is our preferred First Early. The rest are planted towards the end of April.
I use containers (kept in the greenhouse until risk of frost has passed) for the earliest of the earlies that I grow. I have some special Potato Growing Bags which work well (and have lasted many seasons). They fold-flat when not in use, the rest of the year. I also grow some in large containers. In total I grow 3 bags and 3 containers, one of Rocket, 3 of Arran Pilot and 2 of Charlotte (a Second Early, but our favourite for flavour); I put 3 seed tubers in the bags, and 4 in the (bigger) containers. They are all harvested before the outdoor ones are ready; the key benefit of containers is that its means that I don’t have to plant the outdoor ones “sill early” and thus have less effort keeping the frost off the outdoor ones during April and May. Note that usually the whole container has to be tipped out to harvest them, so if you use a really large container that will be a big harvest and I prefer to harvest just what we want to cook, rather than storing any for “later” – the sweetness of New Potatoes deteriorates in storage because the sugar starts turning to starch from the moment that they are picked – which is why home grown new potatoes, cooked the moment they are harvested, will always taste better than Supermarket ones – which have already been a couple of days travelling from the field to the shop.
One further thing I do is to plant some (half a dozen) Salad Potatoes at the same time as the first batch of First Earlies outdoors. Our preference is Pink Fir Apple (who thinks up these names?!) which tastes great, and we find it stores really well too. We like to have these for lunch at BBQ’s in the Summer, so we want to harvest them relatively early and the first few plants are sufficient to tide us over until the main planting is ready.
I plant the first batch in two separate double-rows – the First Early Arran Pilot at one end of Row 1, and then Pink Fir Apple at the same end of Row 2, and then the later planting completes both those rows. So when we come to harvest we start at the beginning of the row, depending on whether we want New Potatoes or Salad, and then we just keep harvesting along the row and, if I have done my sums right!!, by the time we start harvesting the later-planted ones they are ready.
A note on choosing a variety: it is very subjective – just because we like Arran Pilot, Charlotte and Pink Fir Apple its no indicator that anyone else will! Apart from personal preference a lot depends on soil type and growing conditions – my Arran Pilot may taste different to yours, or yours might fall to bits on cooking. My advice, on variety, is to buy a few seed tubers loose (e.g. at your local garden centre) of several varieties and carefully label them when you plant them, and then have a tasting-test when you harvest them to see which you prefer for future years. Taste will vary a bit from year-to-year depending on rainfall, how much manure you give them, and so on, but best you grow the varieties that you have found that you like.