Leafy vegetables adapted to cool Indiana spring and fall growing conditions include lettuce, spinach, mustard, collards, endive, and kale. Many new cultivars of these cool-season crops have improved heat tolerance, making them productive into early summer.
Root crops such as beets and turnips may also be harvested for their young, tender foliage. Greens that produce in the heat of summer include New Zealand spinach and Swiss chard.

Planning

Plan your garden on paper before you plant. Specify which crops and cultivars you want, and where and when you will plant them. Replace early maturing crops with summer crops, and follow summer-harvested greens with a fall planting to make the most of the growing season. Leafy vegetables are well-adapted to band planting, which makes more efficient use of garden space.

Leafy greens grow best in open, level areas where the soil is loose, rich, and well-drained. Although leafy crops tolerate shade better than plants grown for their fruits or roots, at least six hours of sunshine daily will help ensure a high quality harvest. Avoid planting leafy greens in heavy clay or sandy soils. The soil pH should be between 5.8 and 6.8.

Planting

Most leafy vegetables can be planted as early in spring as the soil can be worked. The soil is ready for tilling and planting if a handful of soil crumbles when you squeeze it. If the soil forms a muddy ball when you squeeze it, the soil is still too wet and will form hard, long-lasting clods if you work it.

Get greens off to a good start by incorporating fertilizer when you work up the soil. A soil test will indicate proper rates. In the absence of a soil test, 2 to 3 pounds of a balanced, low analysis fertilizer such as 12-12-12 can be applied to 100 square feet of soil.
Most leafy vegetable seeds may be directly sown in the garden. Most leafy crops have very small seeds and must be planted at the proper depth to ensure good germination (see Table 1). Crops such as lettuce, kale, and collards may be transplanted to get an early start. 

Culture

After planting, you should thin the seedlings to their proper spacing while they’re small (see Table 1); crowded crops compete with each other for water, light, and nutrients and cause a poor yield. You also must control weeds for the same reasons. Many leafy
vegetables have shallow root systems, so be sure cultivation is shallow. Organic type mulch applied around the plants will help control weeds, conserve soil moisture, and cool soil temperature. A few materials that make good mulch are compost, bark chips, grass clippings, clean straw, and hay.

Plants need a steady supply of water throughout their growing season. If rainfall is inadequate, irrigate with 1 to 1-1/2 inches of water per week in a single application. Frequent light sprinklings encourage shallow roots, making plants more susceptible to
drought.

Longer season leafy crops such as spinach, kale, collards, and turnip greens will benefit from a side-dressing of nitrogen fertilizer when plants are about one-third grown. Apply 1/3 pound of actual nitrogen per 100-foot row alongside the crop. For short-season
crops, applying nitrogen during seedbed preparation should be sufficient.

Insects and Diseases

A number of insects are common to many leafy crops including aphids, leaf miners and leafhoppers (for more information, see Purdue Bulletin E-21, <http://extension.entm.purdue.edu/publications/E-21.pdf>). Diseases such as downy mildew may also infect leafy greens (for more information, see <http://vegetablemdonline.ppath.cornell.edu/cropindex.htm>.)

Havesting

Commercial growers find it most economical to harvest whole plants as the leaves develop to full size. Home gardeners can choose that approach or decide to harvest only a few leaves as they are needed, allowing for a longer harvest season from a single planting. If you havest leaves as needed, harvest the outer, more mature leaves first, leaving the young, inner leaves to continue growing. However, collards are an exception: havest the center rosette of collard leaves.

As the days grow longer and warmer, cool-season greens tend to bolt (flower) and become tough or bitter. At this point, it’s best to discard the plants and replace them with a successive planting.

Storage

Most leafy vegetables will keep up to two weeks if stored under cold, moist conditions. Place produce in perforated plastic bags and store in the refrigerator. Crops such as spinach, kale, mustard, and collards may be frozen for longer storage.