University of Vermont Extension
Department of Plant and Soil Science
Anytime News
Article
LEAFY GREENS
Dr.
Leonard Perry, Extension Professor
University of Vermont
Each
year the National Garden Bureau selects a vegetable of the year, which
for 2009
is the leafy greens and for which they’ve provided much
information. You’ve probably seen a sampling of the
diversity of this versatile and easy crop in supermarkets. Leaves
come in many shapes and sizes and
colors (not just green anymore), can be harvested at most any stage,
and eaten
raw or cooked.
A mix of many types is usually seen as
“mesculin.” “Micro-greens” are harvested
as young seedlings, within a couple weeks of sowing seeds, to use in
salads and
sandwiches. Grow them a couple weeks
longer, and you can harvest them as “baby greens.”
There are many types of greens from several plant
families. When most think of greens they
think of the lettuces, mainly the leafy and non-heading types, members
of the
aster or daisy family. The hundreds of
lettuce varieties fall into several main groups. Bibb lettuce has
a whorl of leaves with a
dense heart or center.
Butterhead or Boston lettuce forms a semi-dense ball
of leaves. Leaves are less crisp than
Bibb, and with a buttery texture. A
long-time favorite is ‘Buttercrunch’, a 1963 All-America
Selections winner,
that can be harvested young and used as a small salad. ‘Tom
Thumb’ is even smaller, about the size
of a tennis ball.
Cos or romaine lettuce is commonly used for Caesar
salads with its large wrinkled leaves, and crisp texture and
flavor. It is one of the oldest lettuces, found
growing on the Greek island of Cos and popular with the Romans.
These lettuces take a bit longer to grow to
maturity than other types, about 9 to 10 weeks.
‘Parris Island Cos’ is a common variety with tight
heads. Two heirloom varieties are the short (5 to 7
inches tall) ‘Little Gem’, and the taller ‘Rouge
d’Hiver’ with its reddish
leaves.
Leaf lettuce comes in many colors and leaf types, and
is quick from seed to harvest. If you
can’t decide among the many varieties, choose a blend. They
are adapted to containers and short
rows. They can be harvested at most any
stage, but reach maturity in about 6 to 7 weeks. Cut them above the
growing
point when you harvest and they may grow another set of leaves.
Black Seeded Simpson is popular for its large, light
green, crinkled leaves and tolerance to drought. It can be
harvested over a long period, being
slow to bolt. “Bolting” is when the
lettuce stops growing and sends up a seed stalk, the leaves becoming
bitter. This happens when a plant reaches
maturity, or in response to hot weather.
This lettuce type has some colorful varieties such as ‘Red
Sails’, a
1985 All-America winner with leaves edged burgundy;
‘Merlot’ with dark red
leaves; and ‘Speckles’, a European heirloom variety, with
leaves speckled red.
Least common in American gardens is Summercrisp or
Batavian leaf lettuce. These have crisp
texture and sweet flavor, forming large heads in 50 to 60 days from
sowing. These grow well in hot climates.
A leafy green from another family (Valerian family) is
Mache, also known as corn salad or lamb’s lettuce. Leaves
are glossy, spoon-shaped, mild with a
sweet nutty flavor, and grow in small rosettes.
Garden sorrel, also known as spinach dock, is in the buckwheat
family. Leaves are long, spoon-shaped,
with a sharp and sour or lemony flavor.
It is a perennial, so can be grown into late fall.
Several leafy greens are in the cabbage family. Arugula, also
known as roquette or rocket
salad, is easy to grow and ready to harvest in only 4
to 6 weeks. Lobed leaves have a spicy
flavor, often compared to radish or horseradish. Another quick
green, often harvested only 2
to 3 weeks after sowing as sprouts, is cress. It has curly leaves, and
a
peppery flavor. Don’t confuse cress with
land cress, a perennial that forms dark green rosettes of leaves, or
with
watercress, a perennial that grows in running water or damp areas.
Asian greens have become popular recently, being easy
and quick growing in 5 to 6 weeks.
Mizuna is a type with white stems, and delicate green leaves with
finely
cut edges. It grows in hot weather
without bolting. Tatsoi, also known as spoon cabbage or rosette pak
choi, has
very dark green leaves and a peppery flavor. It withstands cold late
into fall,
even with light snow.
Two other greens in the cabbage family are collards
and mustard greens, popular in southern states as they withstand
heat. Collards have a distinct, cabbage-like
flavor, and can be harvested at any stage.
They’ll even withstand some cold in fall. Mustard greens
have large leaves to a foot
tall, and may bolt with longer days in early summer. Slower to
bolt is the old but good variety
‘Southern Giant Curled’, a 1935 All-America winner.
‘Red Giant’ and ‘Ruby
Streaks’ have reddish leaves, making them attractive in
containers and even
flower gardens.
Lettuce prefers full sun to grow its best, but will
grow in light shade. They are usually
sown directly outdoors in rows, thinning young seedlings by pinching
off at the
base or cutting with scissors. Don’t
discard these, rather add them to salads.
If growing to maturity, allow 8 to 10 inches between plants. Keep
the soil surface moist until seeds
germinate, then water and fertilize as needed.
Harvest by cutting at the base, or pulling whole
plants from the ground. Store in a plastic bag, washing before using.
Greens
are best eaten fresh, but can be stored for a few days in the
refrigerator.
Lettuce, collards, and mustard greens can be stored a few days
longer.
Since
greens don’t store for long periods, don’t sow them all at
once. Sow a short row or two at a time, about 10 to
14 days apart, so you can harvest over a longer period. For late
spring sowings, use varieties that
are slower to bolt in heat and long days.
Plan to sow again similarly in late summer for early fall harvests.
If
you have rabbits in your area you may need to protect your lettuce bed
with
wide-mesh wire fencing, such as chicken wire mesh. This should be
two to three feet high, and
buried several inches in the ground to prevent digging.
Greens
are fairly pest free, but if you do see any, wash off with a forceful
stream of
water. Since you will be eating the
leaves, don’t use chemical pesticides. A
good well-drained soil, and proper spacing, will help to prevent any
disease.
Greens
are good for you, being low in calories but high in vitamins and
minerals. In addition to salads and sandwiches,
consider adding to soups, casseroles, or as a pizza topping. Add
at the end of cooking to avoid them
quickly turning to mush. Asian greens,
collards, and mustard greens are great in stir-fry dishes.
Collards and mustard greens can be boiled or
steamed, which with a bit of salt pork makes a favorite southern dish.
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