Spinach is a leafy green vegetable that grows best in cool weather. Packed with iron, spinach is also high in vitamins A and C, thiamin, potassium, and folic acid (one of the B-complex vitamins). Like most dark green leafy vegetables, spinach also contains the carotenoids lutein and zeaxanthin. Perhaps best of all, spinach tastes great eaten fresh or cooked.
While there are many different spinach varieties with an assortment of leaf shapes and textures, spinach is usually divided into two major categories: smooth leaf and savoy. But this plant has been crossbred so much that it's often hard to categorize. Small-leafed spinach, or baby spinach, has gained in popularity recently and is not necessarily immature spinach leaves but varieties that simply don't get large.
Spinach is very fast-growing and can be ready to harvest in as little as one month after it's planted as seed. In most climates, it grows best when planted in spring and fall, since it needs relatively cool temperatures to thrive.
|Botanical Name||Spinacia oleracea|
|Mature Size||6 to 12 inches tall and wide|
|Sun Exposure||Full sun to partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral (6 to 7)|
|Hardiness Zones||2 to 11|
|Native Area||North America, Central America, South America, Asia|
How to Plant Spinach
You can start spinach indoors or direct seed it in the garden as soon as the soil is workable. Spinach grows quite quickly, so don't start plants indoors more than a two to three weeks before you plan to transplant them outdoors. Spinach also matures and goes to seed quickly, so it is better to re-seed every couple of weeks than to try and plant a large crop to harvest over time.
Sow the spinach seeds thinly in rows spaced about 12 to 18 inches apart, or simply scatter the seeds in blocks. Cover the seeds lightly with soil, firm it in place, and water well. Keep the soil moist until germination. Once the plants have a grown their true leaves, you can begin to thin the plants to about 6 inches apart. Of course, you can eat your thinnings.
As the weather warms, spinach plants will bolt more quickly. Expect to stop sowing spinach seeds sometime in May or June, depending on your climate. You can extend the season slightly by planting in the shade of taller plants and regularly watering your spinach plants.
Plant spinach where it will receive full sun to partial shade. It's advised not to tuck spinach in a flower bed, since too many critters will make a snack of it. You can, however, take advantage of the shadier spots of a fenced-in vegetable garden, where most other vegetable plants would languish. You can also grow spinach in the shade cast by taller vegetable plants and near plants that will begin spreading out as the spinach finishes its season, such as pole beans and corn.
Spinach prefers a well-draining soil with a neutral pH and won't be happy at a pH lower than 6.0.
Water spinach frequently to keep the soil moist; this also helps keep it cool during hot weather. The plants need 1 to 1 1/2 inches of water per week. In dry climates, you may need to water every day, sometimes more often. In any area, don't wait all week, then deep-water; it's better to water several times per week at a minimum.
Temperature and Humidity
Spinach grows best in the relatively cool days of spring and fall, even during the short days of fall. In addition to a spring planting, you can start seeding again at the beginning of August. Keep the seedlings shaded and watered and in the summer heat, and they should be ready to harvest beginning in September. Spinach grows in a range of humidity conditions, including very dry climates.
Because it is such a fast grower, spinach is also a heavy feeder. A fertilizer high in nitrogen, the first number on the fertilizer package, will help produce dark, healthy leaves. Fish emulsion and soy meal are good organic choices for spinach.
- Disease-resistant varieties include 'Melody,' 'Nordic IV,' 'Olympia,' 'Tyee,' and 'Wolter'.
- Good varieties for fall planting include 'Avon,' 'Indian Summer,' 'Melody,' 'Razzle Dazzle,' and 'Tyee'.
- Plants that overwinter well include 'Bloomsdale Long Standing,' 'Cold Resistant Savoy,' and 'Tyee'.
- Recommended types for containers include 'Baby's Leaf Hybrid' and 'Melody'.
Typically, you can harvest spinach four to six weeks from seed. You can begin harvesting whenever the leaves are large enough for your taste. Spinach can be harvested in the "cut and the come again" method of harvesting leafy greens like lettuce. Cut individual leaves, starting with the older, outer leaves and letting the young inner leaves remain to continue growing for a later harvest. You can also cut down the whole plant for a larger harvest. If you cut about an inch above the crown or base of the plant, it is very likely the plant will send out a new flush of leaves.
Spinach leaves are very sensitive to the ethylene gas given off by many fruits, so don't store spinach in the refrigerator with apples, melons, or tomatoes. Spinach can be frozen for later use. Wash the leaves well and allow them to dry somewhat before placing in a resealable freezer bag. Then zap them in the microwave for about one minute on high. Allow to cool slightly and place in the freezer. Frozen spinach is best used within three to six months.
You can continue sowing spinach seeds late into the fall season. In warmer climates, you could quite possibly be harvesting well into winter. If the ground freezes before the plants mature, mulch them with hay and leave them be until the temperatures warm again in spring. Remove the mulch, and the plants should resume growing, giving you an even earlier harvest.
Common Pests and Diseases
Since spinach is grown when the weather is cool and damp, several fungal diseases, such as downy mildew (blue mold) and fusarium wilt, can become problems. Space your spinach plants so they get good air circulation and try to keep water off the leaves in the evening.
Aphids pose a risk to spinach because they can spread viruses. Monitor your crop for aphids regularly and hose them off immediately if you find them.
Several four-legged pests, rabbits chief among them, may also raid your spinach patch. The best defense against them is fencing.
How to Grow Spinach in Pots
If space is tight or rabbits are many, you can easily grow spinach in containers. Even a relatively small 10- to 12-inch pot or a window box will do. Plant as you would in the garden. You will need to water more frequently, since containers dry out faster.