If planting a fall crop, seeds should be broadcast 8 to 10 weeks before the first Autumn frost date. If you get a high germination rate you may need to thin them to about a foot apart.
Collard Greens perform best in full sun, but will tolerate partial shade. About 5 hours of sunlight daily will produce the best flavor. Maintain a regular, uniform supply of water, about 1 1/2 inches weekly . AS with most vegetables a drip system is best but not an absolute essential requirement.
High nitrogen fertilizer and rich amendments such as blood meal, or composted manure can be added to the soil before planting. I usually fertilize the plants again with fish emulsion after they've begun to develop new foliage and also when they start forming heads.
If you use alot of collard greens, a foliar spray of liquid seaweed extract or a nitrogen rich compost added to the soil after each harvest is advisable. Optimal soil pH is 6.5 to 6.8. See Tracking and Adjusting Soil pH
Organic mulch such as finely ground leaves, or bark will help to keep the soil cool and moisture retentive as well as help to suppress weeds. Mulching will also help keep soil; from splashing to the leaves during watering.
Troubleshooting Collard Greens
Clubroot disease is very common - maintaining the proper Soil pH is essential to curtailing this disease - soil pH should be 6.5 to 6.8.
A. Proper sanitary practices are vital to the health of your garden. Proper sanitation can help to ensure disease-free and productive gardens.
B. Try to keep the garden free of any diseased dead or damaged plant materials. Remove cuttings from pruning and trimming and either destroy them - if diseased, or send them to the compost pile. Leaving rotting fruits and vegetables in the garden is like a written invitation to unwanted pests and diseases.
C. If a diseased or dead plant part has to be cut, the microorganism that caused the problem is probably on the tool you just used. Like a surgeon, sterilize all tools by washing in soap and water - rubbing alcohol wouldn't hurt either. If you pinch off diseased plant parts, wash hands before handling any other plants.
D. Keep Weeds under control.
E. Make sure that any compost you put in your garden is completely decomposed to prevent disease organisms that may contain, from spreading.
To prevent diseases from accumulating in the soil, refrain from planting collards or related cole crops in the same location each year. Rotate with a non-cole crop.
Companion Plants for Collard Greens
Good Companion plants for Collard Greens include Potatoes, celery, dill, chamomile, sage, thyme, mint, pennyroyal, rosemary, lavender, beets, onions
Chamomile - Improves the flavor of cabbages and onions.
Avoid planting cabbage near, or in rotation with Rue or Strawberries.
Aromatic plants deter cabbage worms
Inter-plant with Thyme as it repels cabbage worms.
Clover inter-planted with cabbage has been shown to reduce the native cabbage aphid and cabbageworm populations by interfering with the colonization of the pests and increasing the number of predator ground beetles
See also Companion Planting
When the plants are a foot tall, you can begin harvesting outer leaves. When you harvest collard greens, if not harvesting the entire head, it should be done from the bottom up, the lower stem will be made bare, giving the plant a tree like appearance. New leaves will continue grow from the center during cool weather.
Collard leaves should be harvested when they are a dark green, and still young, before they are foot long. Old leaves tend to be fibrous and not as tasty. Start with the lower leaves , then work your way up the stem. The leaves can also be harvested when frozen , the frozen plant will be brittle and easily damaged. Frosts improve flavor.