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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