Originally posted on the VegNet Newsletter, September 4, 2018, By Tim McDermott, OSU Extension Franklin County
Ohio is a FOUR season growing environment. Winter is often under utilized by the backyard grower, community gardener and urban farmer as viable production time. Using inexpensive equipment with a little planning allows for production of spinach over the winter under row cover with surprising success.
Site selection and preparation is very important for over wintered crops. These crops will be challenged by weather and sunlight issues. Areas with shade from deciduous trees in the summer can often be used as an over wintered production location when the leaves fall. Soil enriched with organic matter will hold on to water and nutrients better as both of those inputs are not easily added over the winter season.
Spinach is an excellent choice for over winter production as it is extremely cold hardy. As the temperature decreases the plant increases the sugar content in its vasculature. This essentially acts as an “anti-freeze” to protect the plant. Growth is greatly slowed by temperature and lack of sunlight. Growth will pick back up with the arrival of spring. Seed can be difficult to source in fall if none is left from spring planting. Make sure to plan to have extra seed for next fall’s crop.
Planting needs to be completed prior to Mid-October in most years to allow for decent germination and root growth. Follow the weather prediction models carefully as this can affect timing of planting by several weeks in either direction.
Prior to planting:
- Remove any prior season plant material
- Amend the bed with compost and fertilizer based on prior season crop use
- Observe crop rotation
- Create a seed bed to ensure adequate germination
Row cover was applied immediately after planting. This may or may not need to be done depending on location and security. This row cover was applied as the location will be checked infrequently and deer pressure is a constant concern. Row cover is fairly effective at preventing this predator.
Germination of spinach seed typically takes about 7-10 days. Water as needed to maintain enough moisture for good germination.
If the weather allows, the row cover can be carefully lifted off, making sure not to drop soil or debris onto the leaves, to inspect the planting.
Carefully monitor the weather predictions so that you know when to add or remove additional layers of row cover. The ten day weather prediction showed that the weather would drop from a high in the 50’s to lows in the teens.
A second layer of frost blanket was added to ensure that the micro-climate under the row cover would be adequate to protect the spinach plants. Spinach is extremely cold hardy and will make it through intense cold with proper protection in most cases. Deep cold may terminate less cold hardy crops like lettuce if the temperatures drop very low for any period of time.
Extreme cold, wind, ice and snow were experienced over the end of December 2017 and through the beginning of 2018. Snow is actually helpful to over wintered plantings, providing an extra layer of insulation.
Picture taken on January 16th. Note that the video shown next was taken approximately one week later showing the extremes that are common in Ohio weather. Removing the row cover inappropriately, even for a short time, can interfere with the micro-climate under the row cover and cause damage to the spinach plants.
As the weather allows, once temperatures have risen to at least the 40’s or higher, the row cover can be lifted to inspect the plantings and take a small to moderate harvest. Make sure to replace the row cover with enough time to allow the temperature under the cover to rise prior to any over night cold periods.
Growth will be rapid once spring warmth and sunlight return. The grower will be able to take many harvests during warm days at any point after February in most cases.
As long as harvest is taken before flowering and temperatures have not risen too high, harvest can continue. A large volume of spinach can be harvested from a small area using this method.