Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at askthegardenguy@earthlink.net.
This is probably the kind of question you hate. Can you give me any clue as to why I can’t grow spinach? I grow other leafy greens (lettuce, arugula, raddichio, Mesclun) and other “cold-weather” crops (kohlrabi, beets, Brussels sprouts), but though I have tried for four years, my spinach dies. The soil is fairly alkaline already, but one year I added lime because I read that spinach likes it. No luck. The seed germinates well; the plants become unhappy and refuse to grow and ultimately die. I tried lacing the soil with neem, which is supposed to kill nematodes. Is it just not cold enough here? Thank you, and Happy New Year.
People often comment on the difficulty of growing spinach. Here are a few reasons why:
1. Spinach is sensitive to highly acid soils. The soil pH (soil acidity/alkalinity) should range from 6.4 to 6.8. When the pH drops too low, the following symptoms can occur: low germination, yellowing and browning of the margins and tips of seedling leaves, slow growth and even death of plant. If the pH is too high, leaves may have a general yellowing (chlorosis). When growing spinach, it is important to know the soil pH. Adding lime will raise the pH of the soil, but it is a slow change. A soil analysis will indicate how much lime is needed, if any. If a soil is alkaline, soil sulfur is added to lower the pH. A pH of 7 is neutral, above is alkaline and below 7 is acidic.
2. Most spinach varieties are susceptible to cucumber mosaic virus (CMV). Symptoms include a slight chlorosis of younger leaves and narrow or “puckered” young leaves. Leaves also can have an inward rolling of margins. In advanced stages of 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 crop 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.
Spinach can be grown successfully on a variety of soils, but a fertile sandy loam high in organic matter is preferred.
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 percent; the germination rate diminishes with each year. Beet seed will germinate in temperatures as low as 38 degrees Fahrenheit, but good germination is between 50 F and 60 F. High soil temperatures result in reduced germination. Not that it is pertinent to Hawaii, but spinach is a cold-hardy crop and can withstand temperatures as low as 20 F — perhaps a good crop for the people at the observatories.
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In reference to my Jan. 10 article on mamaki and ko’oko’olau plants, here is response from two readers. Thank you, Merle and Chuck.
1. I was able to get my mamaki plants from Garden Exchange and the ko’oko’olau from Makuu Farmer’s Market. In fact, they have vendors there that sell both plants.
They do very well here in HPP. I no longer need to buy leaves. I have more than enough, so I share with friends here and on the mainland. — Mahalo, Merle
2. Below is a list of sources for native plants. Even if they don’t have what you are looking for listed, it is a good idea to ask anyway. They may be able to obtain it for you or direct you to a source.
1. Ku Maoli Ola: http://www.hawaiiannativeplants.com/
2. Native Nursery LLC: http://www.mauinativenursery.com/
3. Tristar Landscape LLC: http://www.tristarlandscape.com/Tristar_Landscape_Home.html
4. Aileen’s Nursery: http://www.aileensnursery.com/
5. Aikane Nursery: http://www.aikanenursery.com/
6. Ho’olawa Farms: http://www.hoolawafarms.com/Hoolawa_Farms/Welcome.html
Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at askthegardenguy@earthlink.net.