A lot of gardeners have Easter marked as the time to start planting their potatoes. I guess it’s the prospect of a long weekend in the garden or on the allotment that turns our thoughts to planting spuds.
But before you start digging, do you know your ‘first earlies’ from your ‘maincrops’? Have you heard of ‘indeterminates’ and ‘determinates’? What are ‘seed potatoes’ and do you need to ‘chit’ them? Yes, the humble potato (Solanum tuberosum) comes with a language all of its own.
Seed potatoes
Seed potatoes are potatoes from last year’s harvest that you grow this year’s potatoes from. It’s fine to use a few tubers from your previous crop if they have stored well over winter and look healthy. However, using potatoes from your own crops year after year runs the risk of carrying over any disease that might be present. With that in mind, it is also important not to grow potatoes in the same soil each year, as pests and diseases are likely to build up.
In general, it’s best to use a fresh stock of seed potatoes from a garden centre or online catalogue. They will be virus free and guaranteed to give you a tasty, disease-free crop. There will also be plenty of varieties to choose from.
Although it is possible to grow potatoes from store-bought eating potatoes, you won’t get the same disease-free guarantee. If you decide to try this, make sure you buy organic as some eating potatoes are treated with a chemical that prevents sprouting.
First earlies, second earlies and maincrop potatoes
These terms simply relate to the time when you plant and harvest your potatoes. First and second earlies (new potatoes) are often planted at the same time, with second earlies being ready for harvesting a few weeks later than first earlies. Maincrop potatoes are generally planted a bit later, take longer to grow and are harvested later in the year.
When to plant potatoes
There is no hard and fast rule for when you should plant potatoes. It will depend on the temperatures in your region. Later planting (up to a couple of weeks before your last frosts) simply means later harvests, so don’t panic if you can’t start planting over the Easter weekend! As a very general guide…
First earlies can be planted around the end of March/early April for harvesting 10–12 weeks later in June/July. They are the earliest to crop, hence the name ‘first early’. Popular varieties of first early potatoes include:
- Arran Pilot
- Duke of York
- Foremost
- Orla
- Pentland Javelin
- Rocket
- Sharpes Express
- Swift
Second earlies can be planted in mid-April for harvests 14–16 weeks later from July onwards. Popular varieties of second early potatoes include:
- Charlotte
- Estima
- Jazzy
- Kestrel
- Maris Peer
- Ratte
Both first and second earlies tend to be small and flavoursome new potatoes, ideal for boiling and steaming. They are best eaten soon after harvest.
Main crop potatoes can be planted in mid- to late-April for harvesting after 15–20 weeks from late August onwards. Popular main crop varieties include:
- Cara
- Desiree
- King Edward
- Maris Piper
- Navan
- Pink Fir Apple
Maincrop potatoes tend to be bigger than first and second earlies and can be baked, roasted or fried. They also store well over winter.
Chitting
Chitting is the process of forcing seed potatoes to start sprouting a few weeks before they are planted out (see How to chit potatoes). Left in a cool dry place in the light, the ‘eyes’ of seed potatoes produce stubby sprouts called ‘stolons’. When planted below ground, the stolons grow upwards to create the new potato plant.
Chitting is a good way of getting early varieties off to a head start so that they get growing quickly when they are planted, but it isn’t essential.
Indeterminate versus determinate potatoes
I only discovered these terms a few weeks ago and they will completely change the way I grow my potatoes this year, as indeterminate and determinate potatoes have different growth habits.
Indeterminate potatoes produce their crop at intervals along the growing stem in multiple layers. As the plant grows up you need to keep covering the stem (‘earthing up’) so that the layers of potatoes remain underground. You need vertical space for this type of potato and they take longer to grow than determinate varieties. Most (but not all) maincrop potatoes are indeterminate.
Determinate potatoes grow in a single layer just below the seed potato in the top layer of soil. They will benefit from a layer of mulch as they grow to ensure any tubers that break through the surface are protected from the light. The plants do not grow very tall and flower earlier than indeterminate varieties. Most (but not all) early varieties are determinate.
Growing potatoes in containers
With limited veg-growing space, I’ve always grown my potatoes in sacks. For years I’ve been planting 2 or 3 potatoes deep in each sack and ‘earthing up’ around the stems as they grow, thinking that they are growing layers of potatoes. But it turns out that most of the varieties I’ve been growing are ‘determinate’ and have therefore been growing in a single layer. So, this year, I will still plant them in sacks, but I will plant 2 seed potatoes in the bottom third of the sack, then another 2 in the next third. In theory, I should get double the harvest in the same space. Result!
Whatever type or variety of potato you decide to grow, and whether you chit or not, there is nothing more satisfying than harvesting flavoursome home-grown potatoes.
So let me know what you’re growing this year and any potato-growing tips you want to share.