Potato Planting Demystified
Potatoes are an
easy crop to grow but the technical terms and air of mystery surrounding
their cultivation can make them seem more challenging than they really
are. Follow a few simple rules and you too can enjoy a delicious and
prolific potato harvest.
Types of potatoes
Potatoes are described as 1st Earlies, 2nd Earlies and Maincrop. This
means how long it takes for potatoes to be ready for harvest, not when
you should plant them. In fact they should all be planted at the same
time.
1st Earlies should be grown so they can be dug and
enjoyed immediately. Because they are at their most delicious when young
you will not get a big crop from each plant, maybe only enough to feed 4
people, but you can plant a few each week for 3 or 4 weeks to ensure at
least a month's worth of exquisite new potatoes.
You can also do this with 2nd Earlies, especially the
waxy ones like Nicola or Charlotte, but varieties like
Marfona will grow into baking potatoes and will store; they are
like quick growing Maincrops and are grown to beat the onset of potato
blight.
Maincrops will produce a lot of potatoes per plant are
generally grown for storage in a cool, dark, frost-free place.
Potato varieties can be classed as “boilers”, “bakers”, “roasters” or
“mashers”, and it’s important to pick a variety that will do the job for
you. It’s worth remembering that varieties like Arran Victory
and Valor which make good bakers and mashers will also do well
when cooked in fat. Waxy, salad potatoes like Roseval will make
rotten chips, so check out any variety before buying and planting it.
(See Potatoes in our recipe
section.)
Getting potatoes ready for planting
Seed potatoes will start sprouting when they are kept in temperatures
above 3° - 4° C, but they mustn’t be planted out before April in the
Scottish Borders and other northern climes. They are frost-sensitive, so
the leaves will be ‘burnt’ by a late frost. Keep them in a cool,
frost-free room; putting the tubers in egg boxes, preferably with the
broader, upper part of the tuber to the top. In the light, the growing
shoots will stay short and stubby. If kept in the dark, they will
produce weak spindly shoots.
Where and when to plant
Potatoes will grow in any ground that isn’t waterlogged. A sunny spot
will encourage the leaves or ‘shaws’ to stay dry and therefore be less
prone to attacks from blight. Potatoes are very greedy feeders, so the
richer the soil the better. Potato shaws are frost sensitive, so it’s
important that young shoots stay under the soil till all risk of frost
is past. Rising global temperatures do seem to make it safer to plant a
little earlier than 20 years ago, so gardeners will need to take local
advice for planting dates but always wait for a mild spell: pleasanter
for you and the potatoes. Here in southern Scotland, times will vary
from early to mid April, depending on altitude.
How
to plant
In the open ground
1. Dig a trench one spade’s depth and width, piling the
soil to one side.
2. Spread compost along the trench – it doesn’t need to
be as fine as you’d normally use. Well rotted muck is also ideal as the
potatoes are very greedy but not too discriminating.
3. [If possible] Lay a line of ‘leaky hose’ along the
trench. Potatoes are thirsty and it’s very difficult to get the water
down into the soil when the shaws are fully grown. Summer rain won’t do
anything other than wet the leaves, so won’t help the plants. Regular
under soil irrigation, every week or so once the foliage is around 20cm
tall, will give the potatoes the moisture they need and the crop you
want. When grown without adequate amounts of water, you can be sure the
crop will be puny.
4. With 1st Earlies, leave all the growing shoots on
the seed potato, but remove all but 3 shoots on 2nd Earlies and Maincrop
to ensure larger tubers. Place the tubers upright along the trench: 30cm
between 1st Earlies, 40cm between 2nd Earlies and 45cm between Maincrop.
1 metre between rows. You can plant more closely, but you’ll get smaller
potatoes.
5. Cover the tubers with the soil originally dug out of
the trench. You will end up with a low ridge.
6. When the shoots are through and about 8cm tall,
start ‘earthing up’ the potatoes. This means raking the soil from each
side of the row or dreel to make the ridge taller. Repeat this quite
regularly until the foliage gets big. This will make life difficult for
weeds and will make sure you don’t have green potatoes.
. Start harvesting 1st Earlies when the plants start to flower; 2nd
Earlies when the foliage starts to die back; and Maincrop a fortnight
after the foliage has died down.
In Containers
With limited space and a desire for a few delicious 1st Earlies, you can
use large pots [45 litres] or containers with a depth of 35 – 40cm. A
50/50 mix of soil and home made compost is the best growing medium, but
good organic potting compost will also do. You can plant at any time as
the container can be brought into a frost-free shed if a late frost is
forecast.
1. Put 8 – 10cm of the compost mix into the container and place one
tuber on this.
2. Cover with a further 8 – 10cm of compost.
3. You will need irrigation and the simplest way of dealing with this is
to buy an Aqua balance system – cheap and easy to use. A specially
constructed plastic bottle is screwed onto a special dispenser which
sits in a plastic funnel placed into the soil. Lift the system higher
every time you ‘earth up’
4. ‘Earth up’ the potato with compost when it is 8 – 10cm tall and top
up with compost as the shaw grows.
As you bury the growing stem tubers start to develop from the buried
portion, giving you a bigger crop.
5. Harvest 12 weeks after planting. Bon appetit!