Great Lakes was first introduced in 1941 by the United States Department of Agriculture and the Michigan Agriculture Experiment Station and was the first modern “Iceberg” variety. It was created by Thomas W. Whitaker, a world-renowned authority on lettuce, and named Great Lakes, although it was bred in California.

GROWING LETTUCE FROM SEED
Choose the right varieties and you can have lettuce almost all year round. There are
so many types of lettuce to choose from – all with different colours, flavours and
textures – that salad need never be boring! There are two main types of lettuce –
hearting lettuces have a dense centre, while loose-leaf lettuces have open leaves
and no heart. You can also grow a variety of salad leaves that can be picked while
young and tender.
Grow lettuces in full sun on moisture-retentive soil. In some parts of the country
early and late sowings may need protection against cold, using cloches, plastic
tunnels or horticultural fleece. All these types of protection will be available at
garden centres.
There are several different types of hearting lettuces:
Butterhead lettuces have an open habit, are quick-maturing and tolerate
poorer growing conditions.
Cos types have an upright growth habit and oblong head.
Crisphead types produce large hearts of curled and crisp leaves and are
more resistant to bolting (going to seed prematurely); this group includes
iceberg lettuces.
Sow a short row every fortnight to ensure continuity of cropping. Sow seed thinly
13mm deep in rows 30cm apart.
You could also grow lettuces in grow bags or containers – follow the sowing
timings and spacings as below.
Time of sowing depends on when the crop is wanted:
For a summer/autumn crop: sow outdoors from late August. For an even
earlier crop, sow indoors in early August in seed trays and plant out in early
September.
For an early winter crop: sow outdoors in early Autumn and cover the plants
with closed cloches before the first frost.
High soil temperatures in summer can prevent some cultivars from germinating.
Sow in the evening, water with cold water and provide some shade to keep
temperatures down.
