This time of year, everyone is looking for signs of spring: longer days, new buds on trees, birds returning…and spinach in the garden or at the farmers’ market! Spinach is a fast-growing crop that can be planted and harvested early in the season, satisfying the craving for fresh local greens. Twenty-five to thirty days after planting, you can be harvesting tender baby spinach; or wait until thirty-five to forty-five days to harvest an entire bunch. It’s about as close to instant gratification as you can get in the vegetable world!
Here in northern Vermont, spring comes to us later than almost every other place in the country but our high-tunnel is bursting with the healthy green of fall planted spinach. We seeded over a dozen varieties of spinach on Sept 15th and covered the rows with two layers of row-cover over wire hoops. We were able to harvest spinach in December, February and mid-March, and will be
harvesting again next week.
Tony Ingraldi, our trials crew harvest manager, expects to be harvesting spinach every 1 1/2 to two weeks from now through at least mid-May. "The spinach has been incredibly sweet and the re-growths have been very high quality" Tony said. "We've been really excited by the yields - roughly 3 lbs of spinach per 3' x 6' row - definitely enough to feed a family or, on the scale of our 22 x 96 high tunnel, offer some tasty, early greens at market." Tony's favorite variety? He's been impressed by Corvair for its overall quality, flavor and great harvest-ability, "It's upright stems make for very easy cutting."
Spinach seed germinates best when soil temperatures are 32-60°F and achieves the best quality when air temperatures are 55-60°F.
Plant seeds 1/8-1/4” in depth. For baby leaf, sow approximately 40seeds/ft” in 2-4” bands in rows 1-2” apart. For full-size bunches, sow seeds 2” apart in rows or 12 – 18” apart.
Because it is a quick-growing, compact crop, spinach lends itself to succession plantings; sow every 7-10 days for a continual harvest as long as the weather is cool enough to prevent bolting.
Different varieties are better adapted to specific seasonal slots. Some varieties will grow quickly, but later have a tendency to bolt. Other varieties are slower growing and more heat tolerant. If you are planning spinach in successions, keep this in mind when selecting your varieties. During the cooler temperatures of early spring, start out with a quick-growing variety like Samish F1 or Corvair F1 to get a fast crop. As the temperatures continue to climb, switch your sowings to a more bolt-resistant variety like Tyee F1. Try a few sowings of Bloomsdale Longstanding in the middle for excellent spinach flavor.
Harvest, Storage & Marketing Tips
Harvest individual leaves or cut baby leaves 1” above the ground.
Harvest the entire plant for bunched spinach by cutting the whole plant right below its crown. Spinach that is cut above the crown (the growing point) of the plant will regrow and be ready for harvest again in about two weeks. The yield and quality of the second cutting will be somewhat reduced.
Smooth leaf types of spinach are easiest to wash but require more material per bag because they pack more tightly. Savoy types are usually darker green and offer greater heft and loft once bagged, but require more careful washing.
Store washed spinach at low temperatures and high humidity for 10-14 days.
Disease and Pests ID
Spinach Leafminer - Overwinter in the pupal stage in or near spinach fields; adult flies emerge in April and May to lay eggs. Spinach planted very early in the current year or overwintered spinach planted the previous fall will escape most leafmining damage if harvested prior to mid‐May.Early detection is important. Check young seedlings weekly for mining on the cotyledons and first true leaves. Examine 10 plants in 10 locations. Be sure to examine the undersurface of the leaves where mines are most obvious. Look for mines and newly hatching larvae. Yellow sticky traps help determine when adult flies are emerging and will also reduce actual numbers of adult flies in the field. Remove weed hosts, including lambsquarter, nightshade, chickweed, and plantain.
Fusarium Wilt (Fusarium oxysporum f. sp. spinaciae) is primarily soil borne. Once introduced to the soil, it is difficult to eradicate. Crop rotations help eliminate inoculum, and the addition of lime at 2 tons per acre also reduces disease severity by increasing pH to alkaline levels that do not favor disease development.
Downy Mildew (Peronospora farinosa f. sp. spinaciae) symptoms appear as blotchy yellow areas on the upper leaf surfaces of older leaves, with grayish-purple downy old on the lower leaves. The disease is spread by wind or is already present in the soil and splashes up onto the plant during watering or rain. Plants become infected when the surface of the leaf is moist. Presence of the disease can be reduced by three-year rotations with non-host crops. White rust can be a problem for spinach growers, primarily in southern climes; resistant varieties are now available. Disease is favored by warm (72 degrees), sunny days followed by cool nights with dew. Spores are more viable when they experience a period of drying but will not germinate until leaves are wet. spots reduce crop quality and can make spinach unmarketable. Do not plant spring crop near over‐wintered fields. A three‐year crop rotation will reduce pathogen inoculum.
Organic Spinach is pollinated by the wind. Spinach varieties must be isolated by 1/4 mile to prevent cross pollination by wind. Physical barriers such as tree lines, buildings or woods may make it possible to use a shorter distance. Allow plants to bolt and set seed. Some staking may be necessary as plants may reach 3' in height. When seeds are dry, harvest the entire plant and thresh on a tarp. A 1/2 " screen on top of a 1/4" and 1/8" is helpful for cleaning. Spinach seed remains viable for 3-5 years under cool and dry storage conditions.