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Chapter 25: Spinach

Resource Guide for Organic Insect and Disease Management

25.1 Varieties, listed in approximate order of maturity within each class

Variety Leaf Type Pest Tolerance1
DM2 WR3 CMV
Spring Market        
Melody semisavoy 1,2 - H
Tyee semisavoy 1,2,3 - -
Coho semisavoy 1,2,3 - -
UniPack 151 semisavoy 1,2,3,4 - H
Fall Market        
Fall Green semisavoy 1,2 M H
Melody semisavoy 1,2 - H
Samish semisavoy 1,2,3,4 M -
Coho semisavoy 1,2,3 - -
UniPack 151 semisavoy 1,2,3,4 - H
Overwinter        
Vienna savoy 1,2 - H
Coho semisavoy 1,2,3 - -
Unipack 151 semisavoy 1,2,3,4 - H
Processing        
Melody semisavoy 1,2 - H
Tyee semisavoy 1,2,3 - -
Vancover smooth 1,2,3 M -
1: DM = downy mildew; WR = white rust; CMV = cucumber mosaic virus
2: Resistant to downy mildew Race 1, Race 2, Race 3, and/or Race 4
3: L = low, M = moderate, and H = high level of tolerance to pest. When disease tolerance for a particular variety is unknown, line is left blank

25.2 Planting Methods

Spinach is a cool-season vegetable that grows rapidly and develops the highest quality at temperatures of 55° to 60°F and medium day lengths. The seed germinates between 32° and 60°F, and young plants withstand temperatures as low as 15° to 20°F. Seeding in the field can start as soon as the soil is tillable in the spring and can continue through early May. Seeding for fall harvest is done mainly in August. Seeding in cool regions of northern New York for summer harvest is done in May and June. Spinach for an early spring harvest is routinely overwintered on Long Island with seeding dates around mid-September. Overwintering spinach in upstate New York is more of a gamble but can be successful if the winter is mild. Seeding for overwinter plantings in upstate New York should be done in early September.

Table 25.2.1 Recommended spacing

Type Row 1
(inch)
In-row
(plants/foot)
Seed depth 2
(Inch)
Fresh-market 12-18 6-8 0.25-0.5
Processing 12 10-15 0.25-0.5
1: For both fresh and processing markets, the most common arrangement is 4 to 5 rows on 68-72 inch beds.
2: Plant seed deeper in warm, dry soil. Seeding to desired stand is recommended rather than thinning.

25.3 Fertility

Maintain a pH of 6.5 to 6.8 in upstate New York and 6.0 to 6.2 on Long Island. Spinach is particularly sensitive to soil acidity. See Table 25.3.1 below for the recommended rates of nitrogen, phosphorus, and potassium.

Table 25.3.1 Recommended nutrients based on soil tests for spring grown spinach

N pounds/acre P2O5 pounds/acre   K2O pounds/acre Comments
  Soil Phosphorus Level   Soil Potassium Level  
  low med. high   low med. high  
100-125 140 110 80   150 100 50 Total recommended.
50-75 140 110 80   150 100 50 Broadcast and disk-in.
30-50 0 0 0   0 0 0 Apply 3-4 weeks after seeding.

Table 25.3.2 Nonpathogenic disorders

Disorder Description
Air pollution

On the upper leaf surface this injury appears as stippling, flecking, mottling, bleaching, and marginal leaf roll. Look for white, collapsed, irregular patches.

Ontario, Canada, Ministry of Agricultural, Food and Rural Affairs:  Effects of Air Pollution on Agricultural Crops

Bolting Spinach bolts in response to long days and high temperatures. Try slow-bolting varieties or plant earlier.

25.4 Harvesting

Most varieties reach harvest stage in 40 to 50 days under good growing conditions, but 50 to 70 days may be required for early spring plantings. Spinach can be harvested when it has only five or six leaves, but higher yields result when plants have ten to 12 leaves.

Spinach is usually washed before marketing. It is a very perishable product, but if picked early in the day, cooled rapidly after harvest, and topped with ice it can be stored for ten to 14 days. Optimal storage conditions are 32°F and 95 to 100 percent relative humidity.

25.5 Disease Management

25.5.1 Damping-off and Seed Rot
25.5.2 Downy Mildew
25.5.3 White Rust
25.5.4 Cucumber Mosaic Virus

 

25.6 Insect Management

25.6.1 Green Peach Aphid
25.6.2 Spinach Leafminer
25.6.3 Cabbage Looper

 

25.7 Weed Management

 

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Maintained by Abby Seaman, New York State IPM Program. Last modified 2019.