Sweet corn is a type
of maize which has been bred for its high sugar
and low starch content. Once the cob has been
picked the sugar in the kernels is steadily converted
into starch, which is why the flavour of home-grown
sweet corn cooked within an hour of picking is
so much better than the taste of shop-bought corn.
The 6-8in (15-20cm) cobs are borne on 4-6ft (120-180cm)
stems – the tassels at the top of the adult
plant are the male flowers; the female flowers
are the ‘silks’ above the immature
cobs. The plants are decorative as well as useful,
but are regarded as semi-tropical by many. There
is still a widespread view that sweet corn cannot
be grown outside of the southern counties, but
this is no longer true. Choose one of the early
F1 Hybrids which have revolutionised the reliability
of sweet corn in this country. In April raise
the seedlings indoors in peat pots for planting
outdoors once the danger of frost has passed.
Set them out in a sheltered, sunny spot and it
would have to be a poor summer for this crop to
disappoint even as far north as Lancashire or
Use a seed dressing before sowing outdoors. A
minimum soil temperature of 50°F (10°C)
is required for germination.
Expected germination time: 10-12 days
Amount required for a 10ft row: 1/12 oz
Expected yield from a 10ft row: 10 cobs
Life expectancy of stored seed: 2 years
Approximate time between sowing and picking: 14
Ease of cultivation: Not difficult if you can
provide the necessary growing conditions.
· There are two basic soil requirements
– good drainage and enough humus to ensure
that the ground will not dry out too quickly.
Ideally it should be slightly acid, reasonably
fertile and deep, but the situation is more important
than the soil type.
· Choose a spot in full sun which is sheltered
from the wind. Dig in winter, incorporating peat
or old compost if the previous crop was not matured.
Rake in Growmore fertilizer about 2 weeks before
sowing or planting.
Sowing and Planting
· Dig rows 1in (2.5cm) deep and sow in
groups of 2 seeds, 18in (45cm) apart. Remove the
weaker plant. Rows should be 18in (45cm) apart.
· Sweet corn must be sown or planted in
rectangular blocks, not as a single row. This
will ensure effective wind pollination of the
· Outdoors sowing may be reliable in the
south but in other areas sow under cloches or
preferably in pots indoors. Root disturbance must
be avoided so use 3in (7cm) peat pots –
not clay or plastic ones. Sow 2 seeds about 1in
(2.5cm) deep in seed compost – remove weaker
seedling. Harden off before planting outdoors
– leave 18in (45cm) between transplants.
· Southern counties: Sow outdoors in mid
May – the cobs should be ready for picking
in late August or September. For extra reliability
and an earlier crop (late July onwards in mild
areas) sow under glass as described below.
· Other counties: Sow seeds under glass
in mid April-early May and plant out in late May-early
June. Alternatively sow outdoors under cloches
in mid May – place cloches in position about
2 weeks before sowing.
Sowing time (Outdoors): The end of May; Can plant
from mid May under cloches; can extend to early
Sowing time (Indoors): Sow under glass at the
end of April, and transplant at the end of May
or beginning of June.
Picking time: Mid August to mid September; can
extend from late July to early October.
Looking after the crop
· Remove cloches when the foliage touches
the glass. Protect seedlings which black cotton
if birds are a nuisance. Keep down weeds but do
not hoe close to the plants.
· Roots will appear at the base of the
stem – cover them with soil or a mulch of
old compost. The side shoots (‘tillers’)
which may develop should not be removed.
· Water in dry weather – this is
especially important at flowering time. Stake
if the plants are tall and the site is exposed.
· Tapping the tassels at the top of each
stem when they are fully developed in late June
or July will help pollination. Liquid feed when
the cobs begin to swell.
· Each plant will produce one or two cobs.
Test for ripeness when the silks have turned chocolate
brown. Pull back part of the sheath and squeeze
a couple of grains between thumbnail and fingernail.
If a watery liquid squirts out then the cob is
unripe. If the liquid is creamy then the cob is
just right for picking but if the liquid is thick
and doughy you have waited too long.
· Carefully twist off the ripe cob from
the stem. Do this just before it is required for
These ‘open-pollinating’ varieties
produce heavy crops, but they are not as reliable
in our climate as the modern F1 hybrid varieties
which have been specially bred for our northern
Golden Bantam: The only example of an older variety
which you are likely to find. It keeps its place
because it is reasonably early, sweet and with
a good reputation for hardiness.
F1 Hybrid varieties
These varieties have made it possible to grow
sweet corn outside the favoured mild areas required
by many of the older varieties. There are early-,
midseason- and late-maturing types – the
late-maturing are taller and the cobs are often
larger than early-maturing varieties, but always
choose an early-maturing type if conditions are
less than ideal.
John Innes Hybrid: First choice for many gardeners
– early, reliable and vigorous with medium-sized
Early Xtra Sweet: A little later than John Innes
Hybrid, First of All, Earliking, etc, but very
popular because the grains have at least twice
as much sugar as standard varieties. The cobs
are large but there is a precaution – do
not grow near any other variety as cross pollination
spoils the flavour.
First of All: One of the very early ones –
highly recommended for table and exhibition, especially
in areas north of the Midlands. The medium-sized
cobs are about 6in (15cm) long.
Earliking: Medium height with large cobs. An early
variety with a good reputation for sweetness –
a popular choice, especially in northern areas.
Early Arctic: A new one, claimed by the suppliers
to crop 7 days before Earliking.
North Star: The cobs are large, and most experts
recommend this one for maximum reliability in
northern districts and in cold and wet summers.
Polar Vee: Another variety which is recommended
for northern growers. Alternatively you can choose
Northern Belle for the less-favoured areas.
Kandy Kob: Like Early Xtra Sweet, an early variety
with an abnormally high sugar content.
Tokay Sugar: An odd one – as early and almost
as sweet as Early Xtra Sweet but the kernels are
Kelvedon Sweetheart: A new variety which is claimed
to be an improvement on Earliking.
Kelvedon Glory: The most popular of the midseason
varieties. A heavy cropper, producing well-filled
7-8in (17-20cm) the kernels are pale yellow. Recommended
for its flavour.
Sundance: A midseason variety which is claimed
to be an improvement on the better-known Kelvedon