Leafy Greens - Harvest and Storage
In general, practice good hygiene during harvest, to keep lettuce and other leafy greens clean and free of soil and mud. Lettuce will become bitter and tough if harvest is delayed or if the crop is over-mature.
Mixed Leafy Greens
Harvest can start anytime from 3 - 5 weeks after seeding. Leaf flavors and textures change with age, so harvest will depend on yield needs and intended use of the mix. Harvesting is done by hand clipping (1 inch above the soil) or with mechanical harvesters in larger scale production systems. Careful clipping and variety selection allows re-growth for multiple harvests. After harvest, the mix is washed, dried and cooled prior to packaging. Leaves are susceptible to bruising, so handle gently, wash in very cold water, and dry using salad spinners (custom or homemade versions) before storing at 32-35°F with 98-100% relative humidity. Mixed greens are usually marketed quickly (only 1-2 days of storage).
Lettuce, Spinach, Escarole, Endive and Other Leafy Greens
These are harvested at more mature stages of development and are fragile during harvest. Handle as little as possible during the harvest. Most fresh market greens are hand cut and trimmed, boxed in the field then transported to a central cooling facility. Store at low temperatures (32-35°F) and high relative humidity (98-100%) to prevent wilting for up to two weeks. Lettuce and other heading greens are generally not washed before marketing.Heading crops like lettuce, radicchio, and endives
Heading Crops like Lettuce, Radicchio, and Endives
Harvested when the heads are of full size (about 1-2 lbs), well-formed, and firm. Leave some of the wrapper leaves on each head for protection. In large production areas like California, heads are graded by size, may be wrapped in plastic, and then packed in cartons in the field before cooling prior to shipping. Leaf, bibb, and cos types are cut, trimmed, and tied before boxing. Store at 32-35°F and 98-100% relative humidity. Expected yields of iceberg lettuce is approximately 500-700 cartons (40 lb box) per acre (24-30 heads/box), bibb and leaf lettuce approximately 700-1000 cartons (25 lb box) per acre (24-30 heads/box) and romaine approximately 700-900 cartons (25 lb box) per acre (24-30 heads/box).
Turnip, Mustard, Collards, and Kale Greens
Harvested when stalks are fairly young and tender. Whole plants or individual leaves may be harvested and rubber bands (or ties) can be used to group loose leaves. Leaves are bunched, three to five stalks per bunch, prior to washing and cooling. Leaves that are discolored, dying or unattractive are removed during bunching.