Tips & Techniques for Growing Greens
Growing Kale
cabbage butterfly
cabbage worm
Varieties of Greens
There are several types of greens.  Four of the most common types are turnip greens, mustard greens, kale and collards.   There are several varieties of turnips.  Some are grown primarily for the greens whiles others produce turnips.  The most typical are the ones that grow purple topped globe shaped turnips.  The leaves have a slightly strong and distinctive taste and are best if eaten when they are still young and tender.  There are several varieties of mustard greens.  Some are hotter than others and may have frilled edges.  Young kale leaves have a mild flavor and no hot taste.  Collards, a southern favorite, are not quite as tender and mild as kale but are high in calcium, iron and vitamins.  They are an antioxidant rich food.
Preparing the Soil
Preparing the soil to plant greens can be as simple as tilling and marking off rows.  If you prefer planting a bed of greens, you will need to rake the ground to form the bed.  In either case, the soil needs to be very loose since the seeds of most greens are very small.  If you do not have sandy soil, you may want to till in some compost to keep the ground from getting too hard while the seeds are germinating.  To avoid much of the work pulling weeds, I prefer planting greens in rows.  If you space the rows so the middles are slightly wider than your tiller, you can do most of the weeding with your tiller.  To prepare the rows for planting, make a straight shallow trench.  The seed can then be sowed in the trench.  The location of greens within your garden is not that critical, since they are compatible with most garden plants and can even grow well in partial shade.
Planting Greens
Greens can be planted early.  They can handle cool weather but it is best to wait until after the last frost.  Sow the seeds evenly, but not too thick, either in a row or in a bed.  This can be difficult, so you may need to thin them after the plants are a couple of inches high.  If you are planting turnip greens and plan to harvest turnips, you will need to thin them to allow room for the bulbs to make.  Cover the seed with approximately a quarter of an inch of dirt.  If you are planting them in a bed, you may want to just rake them in lightly.  If you plant them too deep, they will not be able to push up through the ground.    
Weeding & Plant Maintenance
If you plant your greens in a bed, you will need to pull the weeds that come up in the bed to prevent them from smothering out your small plants.  Greens grow fast but some weeds grow even faster.  If you plant the greens in rows, you should be able to remove most of the weeds from the middles and next to the plants with your tiller.  You will have to pull a few weeds that are between the plants.  You may want to thin at the same time.  You should till and pull weeds about three or four times during the growing season.  If water is available, you may want to water several times since greens need adequate moisture to support their fast growth. 
Controlling Diseases and Insects
Greens usually can be grown without too many problems with insects or diseases.  However, there are several types of insects that will eat the leaves of greens.  The most common seems to be a green cabbage worm which is the larva of a white cabbage butterfly.  The worms eat holes in the leaves.  They can be picked off or, if the problem is severe, you may choose to use a common garden dust or spray.  Aphids can be a problem, if they get too well estabished on your plants.  Common garden insecticides don't aways work against aphids.  A mixture of water, dishwashing soap and cooking oil may be more effective.  Also, I have found groundhogs to be a problem with kale and collards.  They don't seem to like turnips or mustard greens.  I have resorted to putting part of my garden within a fence and use a garden spray for the cabbage worms.  If you find that a garden dust or insecticide is needed, make sure you read and follow the directions on the containers.  For specific details on controlling diseases and pests, click on the "Gardening Resources" tab and go to the Sources of Information on Vegetable Garden Diseases and Pests.
The leaves of greens are best picked when they are small and tender.  They taste better and are most nutritious if eaten soon after harvest.  If you break off selected leaves or cut the leaves off about two inches above the ground, the base of the plants should generate new leaves and continue to produce greens.  Turnips can be pulled as soon as they are large enough to eat.  Greens are best eaten fresh but can be canned successfully.  When canning turnip greens some people cut up some turnips and put a few pieces in each jar.  Mustard greens and kale can be very tasty canned, if the leaves harvested were small and tender.