Four distinctive types of lettuce grown exclusively in containers include crisphead, butterhead, leaf lettuce and romaine, which is also known as cos. Crisphead and romaine lettuce produce heads with green leaves inside and outside, while butterhead's inner leaves are cream colored. Butterhead, crisphead and romaine develop upright, circular heads with tight-folded leaves. Leaf lettuce is the only one of the four types that does not form a head. It instead develops crinkled, green leaves.

Project Supplies
Potting soil
Large bucket
Plastic containers
Lettuce seeds
Spray bottle
Plastic wrap
Liquid fertilizer
Plastic bags
Rubbing alcohol

Step 1
Place well-drained potting soil into a large bucket and add water. Mix water and soil together with a trowel until damp. Be sure to choose potting mix that contains a combination of peat moss, vermiculite and perlite to prevent weeds and fungal diseases.

Step 2
Fill several plastic containers with the potting soil. Containers should be 12 inches in diameter and 5 inches long. Level with the top edge of the soil with the trowel. If using previously used containers, clean them with 1 part bleach, 9 parts water and rinse well.

Step 3
Plant lettuce seeds in individual containers ¼ inch deep or according to the depth listed on the back of the lettuce seed packet. Cover the seeds over with potting soil. Settle soil by misting it with a spray bottle filled with warm water. Place of piece of plastic wrap over the top of the container to retain moisture until seeds germinate, which should occur in one to two weeks.

Step 4
Place pots in an area that receives six to eight hours of direct sun. Lettuce seeds generally need a warm, moist environment to germinate with temperatures 60 to 68 degrees Fahrenheit. Temperatures under and above the recommended range will wilt leaves and prolong growth.

Step 5
Mist with cool water daily to keep the soil evenly moist. Apply liquid fertilizer at half strength once a week.

Step 6
Harvest lettuce three to four weeks after germination when heads and leaves are young and tender. Remove the outer leaves with a sharp scissor or cut the plant 1 inch above the soil’s surface to harvest crisphead, butterhead and romaine lettuces. Leaf lettuce is harvested by removing the outer leaves with a scissor to promote growth in the center leaves.

Step 7
Wash newly harvested lettuce and store in plastic bags in the refrigerator for one to two weeks.

Before and after harvesting disinfect scissors in rubbing alcohol to prevent the spread of disease and germs.

Inspect lettuce plants for root rot, which occurs due to overwatering. If suspected, spray plants with fungicides. If that does not work, remove the plants by hand and discard them in the trash.