Monday, June 10, 2013

The Difficulties of Growing Spinach


For many gardeners, it’s a matter of throwing the spinach seed on the ground and later harvesting a plentiful crop. Yet others struggle; here are a few reasons why:

1. When growing spinach, knowing the soil pH is important. Spinach is sensitive to highly acid soils. The soil pH (acidity/alkalinity) should range from 6.4 to 6.8.  When the pH drops too low, the following symptoms can occur:  low germination, yellowing, slow growth, browning of the margins and tips of seedling leaves and even death of the plant. If the pH is too high, leaves may have a general yellowing (chlorosis).

 A pH of 7 is neutral, above is alkaline and below 7 is acidic. A soil analysis will reveal the pH.  If needed, adding lime will slowly raise the pH of the soil.  If a soil is alkaline, sulfur is added to lower the pH.

2. Most spinach varieties are susceptible to cucumber mosaic virus (CMV).  Symptoms include a slight chlorosis of younger leaves along with narrow or "puckered" young leaves. Leaves also can have an inward rolling of margins. In advanced stages of the disease, the plants often appear stunted. Melody F1 and Savoy hybrid 612F are reported to be resistant to CMV.

3. Spinach is a cool-season vegetable and belongs to the goosefoot family (Chenopodiaceae) along with beets and Swiss chard.  They thrive best during the cool, moist seasons of the year. During periods of warm weather and long days, the spinach plant will bolt - stop its leafy growth in favor of flower and seed production. The Tyee variety is one variety that is slow to bolt.

4. And lastly, it is important to use new, fresh seed each year. Spinach seed that is more than a year old, rarely germinates over 80%; the germination rate diminishes with each year. Beet seed will germinate in temperatures as low as 380F, but good germination for spinach is between 50 and 60 0F. High soil temperatures result in reduced germination. Spinach is a cold-hardy crop and can withstand temperatures as low as
20 0F.

Spinach can be grown successfully on a variety of soils, but a fertile sandy loam high in organic matter is preferred.

Ask the Garden Guy Science Based Answers to Garden Questions, is an excellent resource book for the gardener. Some popular topics include Slugs and Snails, Organic Pesticides, Reasons, Why Vegetable Seeds Do Not Germinate, What’s So Hot about Manure? and Mushrooms in the Lawn.  Purchase by clicking on the image of the book above.