Fall-planted spinach is a wonderful crop, and now is the time to plan your plantings, and even start sowing if you are in cooler parts of the country. Unlike spring sowings, plants started in the fall won’t bolt, as the days are getting cooler and shorter as the plants mature. If your climate is suitable for overwintering spinach, or you can protect the crop, you can keep the plants alive for early spring production. Overwintered plants will bolt a few weeks ahead of spring started ones.
Daylength of more than 14 hours triggers bolting in spinach. All of us, wherever we are, have 12 hours of daylight at the spring equinox and the fall equinox, and less than that from fall to spring. If temperatures are in the right range, we have more than six months of suitable spinach growing conditions. Hot weather will accelerate bolting once the daylight trigger has been reached, as will overcrowding (with other spinach or with weeds) and under-watering. Here in central Virginia, at a latitude of 38N, we get 14 hours of daylight May 8, and spinach is definitely a lost cause after then.

Spinach is very fast-growing, harvestable in less than 50 days, and can be a welcome change after summer crops. (Summer can be short of leafy greens, other than lettuce and chard, or stored cabbage). The flavor of spinach is sweetest and nuttiest in cold weather.
   
Varieties
Some people love their heirloom varieties, and the Bloomsdale varieties (Winter and Long-Standing) are reliable. For bolt resistance, though, we go with the hybrids. Here is something that was news to me: on the East Coast, bubbly savoyed spinach varieties are preferred, while on the West Coast, smooth-leaved ones are popular. So if you have recently moved a long distance and intend to sell spinach at the farmers market, find out which kinds are likely to sell more easily. ‘Tyee’ is the variety we like best, and most years now, it’s the only one we grow. One spring I was entranced by the catalog description of ‘Giant Viroflay’. It certainly grew big leaves, but not for long, and then it was all over. We experimented with smooth-leaved spinach, thinking it would be easier for cooks to clean, and it probably is. The disadvantage is that smooth-leaved spinach wilts quickly after harvest, and needs attention to fast picking and prompt chilling. Nowadays I order a big bag of semi-savoyed ‘Tyee’ each spring and I’m all set. It is worth noting that seed viability declines to less than 80% after a year.

‘Space’ is a popular smooth-leaved type. Paul and Sandy Arnold in Argyle, NY, wrote in the June 2005 Growing For Market about their spinach growing in the Northeast. They use ‘Tyee’ for spring plantings from transplants. In summer they switch to direct seeding the smooth-leaved ‘Space’. They sow in the evening and water immediately and often until the seeds germinate. Sowings are made once a week, unless 90°F weather is forecast, in which case they wait for it to cool off before planting. They reported that ‘Tyee’ is faster-growing than ‘Space’, and so better for spring use. ‘Space’ can grow all summer there, without bolting.

Other varieties that are recommended for hot-weather planting include ‘Indian Summer’, ‘Olympic’ and ‘Spinner’. ‘Olympia’, ‘Samish’, ‘Avon’ and ‘Coho’ are cold-hardy varieties.

Crop Requirements
Spinach is a cool weather crop, and is hard to germinate in warm conditions. Like most leafy greens, spinach appreciates a fairly rich soil, plenty of water, good drainage, pH of 6.0-7.0 and moderately good light. Partial shade can be an advantage once the weather starts to warm, so take this into account when planning crop layouts.

Spinach is tolerant to temperatures down to 20°F, and in areas where continuous snow cover is not to be had, row covers on hoops will protect the plants. If you use row cover without hoops, the abrasion of the fabric on the leaves causes unsightly damage, and also the leaves are more likely to freeze to the fabric if you get wet weather followed by freezing nights.

One suggestion (in the October 2000 Growing For Market), is to sow oats broadcast into the spinach at planting time. The oats will grow up with the spinach and protect it from the worst of the early winter weather, and then will be frost killed at 20°F.

Spinach that has been overwintered will benefit from a nitrogen boost in the early spring, either side dressing or foliar feeding.

Sowing
In spring, spinach is sown as early as possible. In the fall, it can be started eight weeks before the fall frost date if the weather is not too hot. Our average first frost date is October 14, which would indicate mid-August as a starting date, but it’s too hot here then, so we wait a couple of weeks. Here in central Virginia, we are in USDA hardiness zone 7, as well as zone 7 for summer temperatures – right in the middle on both scores. The American Horticulture Society publishes the heat zone map:  http://www.ahs.org/publications/heat_zone_map.htm and the USDA publishes the plant hardiness map:  http://www.usna.usda.gov/Hardzone/ushzmap.html
For most of us, to have sales when the cool weather of fall arrives means sowing or transplanting in hot soil in September, especially when growing it in a hoophouse. We sow our first fall spinach September 1-5. We might risk an earlier sowing if the season was a cool one. Laying shade cloth over the spinach beds a week before sowing cools the soil enough to allow germination. Shade cloth on hoops can help spinach establishment. Noon-time watering can help cool the soil and give the seed the best chance.

Sowing sprouted seeds is a method that works well for us. We soak the seeds in water overnight, then drain and put the jar in the refrigerator for a week. Turning or rolling the jar daily helps get even germination, but it’s also possible to totally ignore them for the week and then still have viable seeds. I speak from experience!

This is a big planting, and feeds us from the middle of October until late April. We protect it with rowcovers  and pick it throughout the winter, whenever it is big enough. We usually have about seven beds, and can pick one each day in October, November, February, March, when the weather is not too awful to go out in. Spinach will make some growth every time the temperature is above about 40°F.

Our second sowing is usually September 20-30, and this one overwinters small, and does not reach harvestable size until early spring. This planting will bolt in the spring at a date between the first fall sowing and the spring sowings. In some climates, fall and winter harvesting reduces the survivability of spinach plants, but the small plants overwinter well – the ideal size would fit under a small teacup. Plants either smaller than this or larger than this are not so cold-tolerant.
Sowings after the end of September can be made in warmer climates: until Oct. 15 in South Carolina, and Nov. 15 in Louisiana.

Days to emergence
Soil temp. °F    Number of days
32    62
41    22
50    11
59    7
68    5.7
77    5.1
86    6.4
>86    don’t bother

In terms of days to emergence, as shown in the table above, spinach comes up quickest at 59-86°F. But days to emergence is only half the story with spinach! (I found this out the hard way). The percentage of normal seedlings that do emerge is also vitally important. At 41°F 96% of the seedlings will be normal. 91% at 50°F, 82% at 59°F, then there is a rapid drop-off: only 52% normal at 68°F, 28% normal at 77°F. So, combining these two factors, temperatures of 50-59°F should produce plenty of normal seedlings in a reasonable 7-12 days. This can be hard to achieve in late summer!

Sow seed 0.5” deep. Rows can be anywhere from 3” to 12” apart, depending on your equipment and the space available. Plants are thinned to 4-6” usually.

Transplanting
Spinach transplants very easily, and so seedlings can be started in a shade house or an air-conditioned house. Just be sure to water the transplants daily for a few days until you are sure they have taken. Putting a plant in beside every drip emitter (while the irrigation is running), is a wonderful method for those using drip tape.

We plant on a 6” spacing in the row, with rows about 9” apart. Closer row spacing is possible, if you have raised beds.

Spinach grows fastest with temperatures in the 60s. Spinach grows beautifully in a winter hoophouse. For ours, we make a first sowing (of sprouted seeds), on September 6, then on October 24 we establish a second patch, either direct sown, or by transplanting spare plants from the #1 sowing, which helps to thin out that sowing. Next we make a small sowing November 10, for plants we will use later to fill gaps as they occur in the lettuce beds. Not much growth happens in our hoophouse during the shortest days, November 21-January 21 (which Eliot Coleman, in his book Winter Harvest Handbook, calls the Persephone months). But if anything grows, it is the spinach. It is quite phenomenal how much growth spinach can make in our winter hoophouse! We just harvest whenever it looks big enough, working our way up and down the beds, and the various plantings. As the days begin to lengthen again, we make a fourth hoophouse sowing around January 15-17, to fill more gaps – we don’t worry about crop rotation, we just pop a plant in wherever a space appears. On January 24 we make a sowing in the hoophouse for transplants to be moved outdoors. We’ve tested this method against plug-flat grown plants started on the same date, and they do equally well. The advantage of the hoophouse open-ground sowing is that it’s quicker to sow, and less work from then on – it gets watered along with everything else, and dries out less quickly than flats do. We plant this outdoors around February 21, 4 weeks old. At that time of year, bare root transplants don’t get hot enough or dry enough here to suffer.

Pests and diseases
Voles can be a problem for us, eating the roots. We use plastic “Intruder” mouse traps from the hardware store, baited with peanut butter or fruity bubble gum. Eliot Coleman in his new book The Winter Harvest Manual shows an interesting box for holding mousetraps that seem inviting to voles. We plan to try that this winter.

We have not been troubled much by insect pests, but others have to deal with web-worms and leaf-miners.

Diseases have not been a problem for us either. John Navazio has done some research into disease-resistance, and found that the glossy-leaved variety ‘Wintergreen’ has some Fusarium resistance. ‘Ozark II’ also has Fusarium resistance, but is not commercially available. (It’s a research variety). ‘Tyee’ has some resistance to Downy Mildew, but ‘Samish’ and ‘Unipack 144’ have better resistance. ‘Cascade’ is prone to many diseases.

The main troubles we have are yellowing leaves from near-drowning experiences, frost damaged patches, and abrasion damage from row covers.

Harvest
There are three main ways to harvest spinach, four if you count using the thinnings from direct sowings.

We generally harvest by the leaf, with scissors (the hand forged Chinese scissors from Lee Valley make very good harvesting tools).  www.leevalley.com  At $11.50 for a set of 4 pairs, from 5-1/2” to 8-1/2”, they are good value, traditional tools.

Harvesting a leaf at a time has the advantage of producing an attractive product—all whole leaves. I believe it also is least damaging to the plant and likely to give the highest total yield over the life of the plant. It can be rather slow, depending on the skill of the harvester (and the outdoor temperature!)

The “buzz-cut” method is much faster, and the plants live to carry on producing more. Gather the leaves and cut them all, an inch above the crown. The plants do take longer to recover from buzz-cutting than from leaf-harvesting. If you are making a salad mix, the fact that the leaves are cut might not matter. This is a good method when time is at a premium. We use this method in the spring, when the plants start to grow tall in preparation for bolting. If your plants are frost damaged, with yellow-white patches, this method might not work as well as the leaf-harvesting method, as you might have a lot of sorting to do.

The final method is the single-harvest: cut the plants, or pull up and chop, then till in the crop residue and start again. This produces the most beautiful spinach, and possibly is the quickest harvest technique. Obviously, this method isn’t suitable if you hope to overwinter your spinach, as it kills the goose that lays the golden eggs, and it will be too late in the year to resow. Season extension into winter relies on extending the harvest period by keeping plants alive and productive for multiple harvests. But in early fall, or in spring, this method has its place, as a quick catch-crop before a longer term food crop or winter cover crop is sown or transplanted.
                         
Seed storage
We usually put our spinach seed in double zip-lock bags in the freezer from April till we need it at the beginning of September. During the winter our seeds are stored in plastic food containers in a cool basement.

Pam Dawling is the garden manager at Twin Oaks Community in Virginia. The gardens provide the 100 residents with nearly all their fresh and preserved fruits and vegetables. Pam can be reached at pam@twinoaks.org.