Select a full-sun planting site with healthy soil drainage. Look for a site that gets a minimum of six hours of direct sunlight per day. Avoid sites prone to flooding.
Amend the soil with high-nitrogen organic fertilizers and coarse mulch to improve nutrition, aeration and drainage. Work 3 parts of well-rotted compost, 2 parts of alfalfa meal and 1 part of redwood mulch into the soil to a depth of 10 to 12 inches, using a garden fork or tiller.
Sow spinach seeds in the prepared soil approximately four weeks before the first fall frost in your area. Push the seeds into the soil to a depth of a 1/2 inch. Allow 2 inches of space between each seed, in rows spaced 8 inches apart, to ensure healthy development.
Water the spinach seeds with a 1/2 inch of water immediately after planting. Continue to provide the spinach with up to 1 inch of supplemental irrigation each week to maintain lightly moistened soil.
Cover the spinach with a glass or polyurethane cold frame after planting, to protect it from snow and damaging winds. The frame allows the spinach to freeze at night and thaw during the day, increasing its sugar content.
Fertilize the spinach with an application of fish emulsion as soon as you observe new spring growth. Apply the fertilizer according to the instructions on the product label.
Harvest the sweet icy spinach before the last spring frost to ensure the best taste and texture.