Winter Growing Research Results

Eight farmers completed research projects on winter growing and storage in the winter of 2009-2010. A summary of their on-farm research and results follows. A link to a PDF of the full report submitted by the farmers follows each summary.

Note:  this report is the result of a Northeast Sustainable Agriculture Research and Education (NESARE) partnership grant that NOFA-VT received (ONE08-084) which funded farmers to conduct on-farm research on winter growing, season extension, and storage. [Why did we apply for this research grant?]

 Are you a farmer interested in participating in research like this? Please contact NOFA Vermont: (802) 434-4122 or info@nofavt.org

Winter Growing:

1.  Champlain Orchards: Broccoli under Row Covers
2.  Luna Bleu Farm: Watering Impacts on Soil Temperature
3.  Screamin’ Ridge Farm: Examining Bed Pitch Impact on Soil Temperature
4. Valley Dream Farm: Row Cover Comparisons
5.  Walker Farm: Row Cover Height

 Winter Storage:

1. Jericho Settlers Farm: Winter Carrot Storage to Maintain Quality and Minimize Staining
2. New Leaf Organics: Carrot Storage Systems
3.  Rockville Market Farm: Post-Harvest Winter Squash Treatments

 

Winter Growing

Five farmers conducted research on growing winter crops in unheated hoop-houses, as follows:

 

1.  Champlain Orchards: Broccoli under Row Covers

Champlain Orchards examined transplanted broccoli under one or two row covers in a hoop-house. They were interested in this experiment because of the NE-SARE funded work University of New Hampshire Extension Professor Becky Grube-Sideman has done on winter sprouting broccoli as an alternative tunnel crop. Broccoli transplanted into pots at the end of October and transplanted into the ground in mid December was grown under one or two row covers. Plants were evaluated for size and quality through mid-January.

Results showed that the number of row covers was less important than varietal differences. Champlain Orchards plans to experiment with more cold-hardy crops like spinach, kale and other greens next year.

[download full farmer report]

 

2.  Luna Bleu Farm: Watering Impacts on Soil Temperature

Luna Bleu Farm wanted to determine how watering at different times of day impacted soil temperature and thus, spinach growth. They were concerned that cold water would chill soil and reduce growth. They compared the temperature of watered to un-watered greenhouse soil in their experiment.  Their findings are summarized below:

• Watering time:  They had to water for 90 minutes to put a sufficient amount of water on their spinach. This was longer than the 20-minute watering they had initially intended. By watering for 90 minutes at a time they found they decreased the overall labor required to water plants over the season.

• Temperature results showed that their water temperature was warmer than expected and that watering actually warmed the soil by 5 degrees Fahrenheit on average. By watering as early in the day as they could, usually by 9:00am, the water darkened the soil and enabled it to absorb more solar rays, gaining up to another 5 degrees of warmth by the time the row covers needed to be put back on the spinach later in the day. 

• Water only on sunny days during the coldest part of the winter.

Luna Bleu will continue to use these three watering management techniques in their winter growing.

[download full farmer report]

 

3.  Screamin’ Ridge Farm: Examining Bed Pitch Impact on Soil Temperature

Screamin’ Ridge Farm compared the soil temperature of two flat beds to two beds with a southern slope by taking 4 temperatures in each bed over the season. The temperature inside the high tunnel and the outside air temperature were also recorded.

Results showed no difference in soil temperature based on the bed pitch during the coldest part of the winter; however, as the sun moved higher in the horizon after February 4, the pitched beds warmed more quickly. Many variables in this study impacted getting clear results, including variable bed height, snow pile shading of greenhouse beds, and beds containing different types of winter crops. It was noted that the one bed that was raised to16 inches, which was twice the height of all the other beds at 8 inches high, attained ambient air temperatures more quickly.

Screamin’ Ridge Farm plans to further examine higher beds, and possibly subsoil heating, in the future.

[download full farmer report]

 

4. Valley Dream Farm: Row Cover Comparisons

Valley Dream Farm conducted a row cover comparison in unheated hoop-houses to determine the best way to extend their growing season. In one hoop-house, they compared no row cover, one row cover and two row covers on Magenta lettuce.  The growth rate was measured by comparing size from October 1st to November 28th. In another hoop-house, they examined one layer of row cover with and without hoops to two layers of row covers with and without hoops on Space and Remington spinach. Growth rate was measured in terms of pounds of product from October 1st to December 20th. December 20th was their last harvest because this greenhouse was destroyed by 100 mph winds.

Valley Dream Farm found that lettuce grown with two row covers was 1/3 larger than that grown with one row cover. Lettuce grown with no row covers had no growth. They also found that spinach grown without hoops was similar to baby spinach: shorter, thinner, and less appealing. The number of covers did not matter. In the trials without support hoops, all test areas had similar weights of about 6.5 pounds, while spinach grown with hoops had approximately 2 pounds of additional weight and was of higher quality.

Valley Dream Farm plans to use these results to grow their next winter crops.

[download full farmer report]

 

5.  Walker Farm: Row Cover Height

Walker Farm examined the height of row covers over greens. Winter growers know that high tunnels hold more volume of air to the tunnel skin and are thus more resistant to heat loss and temperature changes. Does this hold true for row covers within the hoop-house? Walker Farm used various heights of row covers to determine how increasing the volume of air under row covers influenced the temperature. They compared three heights of row cover: 1) directly on the crop, 2) with hoops one foot above the crop, and 3) with hoops two feet above the crop.

Results showed that while temperatures varied from relatively mild in January to moderately cold in February, the differences among the various heights remained fairly constant.  The two-foot high cover consistently provided warmer temperatures during the night.

A second important management task they learned from their observation was the importance of taking off all the row covers each sunny morning to allow the crop direct light. While temperature is important for growth and protection, light is at a premium from mid-December to mid-February and management of the covers for optimum growth is essential.  

Walker Farm will continue to grow winter greens; they would like to develop an easy and convenient method to cover and uncover the crops with the two-foot high row covers.

[download full farmer report]

 

Winter Storage

Three farmers conducted research on best crop storage practices, summarized below:

 

1. Jericho Settlers Farm: Winter Carrot Storage to Maintain Quality and Minimize Staining

Jericho Settlers Farm wanted to determine the best storage system to produce high quality carrots. They evaluated 4-pound bags of harvested Napoli carrots under four different treatments: 1) washed, bagged in perforated plastic bags and put into cold storage; 2) cold storage unwashed for one week, and then washed and put back into cold storage (delayed washing while stored under high humidity); 3) barn storage for one week and then washed and put into storage (delayed washing while stored under low humidity); and 4) stored unwashed and washed just before evaluation.  Half the carrots were evaluated in February and half in April for staining, flavor with a Brix meter, and crunchiness.

Jericho Settlers Farm found that the carrots washed immediately post-harvest (treatment 1) were still of marketable quality in respect to all three attributes (staining, flavor, and crunchiness) at the end of winter storage (harvested November 2009 and stored until April 2010). Although they had expected some lost crunchiness or sweetness (Brix) as compared to the other treatment groups, they did not find this to be the case. Treatment 1 had the lowest staining of any treatment. Crunchiness was only reduced in the group which was stored for 2 weeks post-harvest in a dry (open barn) environment (treatment 3). Brix levels were lower for all the groups in the April evaluation and the February Brix readings were lower than the November readings taken immediately post-harvest (averaged 10.2 Brix). Treatment 4 Brix readings were higher in April than others, but these carrots were not marketable due to staining. 

Jericho Settlers Farm also noticed that the carrots stored in clean nylon-weave grain bags (as compared to perforated plastic bags) were of substantially better quality than all 4 treatment groups in the experiment.  These carrots were not part of the initial experiment, so there was neither official replication nor evaluation in November or February. They did take Brix readings, crunchiness, and staining evaluations of them in April. These carrots had 1% staining, with most carrots not being stained at all, and they had Brix readings of 6.0 on average and were very crunchy. All of the many bags like this in storage were of excellent quality in April.

Based on this research, Jericho Settlers Farm will wash all carrots post-harvest in the fall when they still have plenty of staff, and then they will be stored until needed for the winter CSA. The farm does not need to invest in a winterized washing station. They plan to store the majority of their carrots in clean nylon-weave grain bags as opposed to plastic bags and will examine purchasing these bags with their logo on them to facilitate wholesaling winter root crops.

[download full farmer report]

2. New Leaf Organics: Carrot Storage Systems

New Leaf Organics researched storage methods for carrots in their new root cellar. All carrots were cooled from field heat for 3-4 hours, washed, and packed. There were four packing treatments: 1) 25lb. plastic ventilated bags; 2) waxed boxes packed with dried maple leaves; 3) waxed boxes packed with sawdust; and 4) green harvest totes. The harvest totes were packed with 50 lbs of carrots; all three other methods each held 25-35 lbs. The carrot area in the root cellar was kept at 34-36 degrees with a relative humidity of 90-95 percent.

New Leaf Organics found that all methods of storage seemed to be successful on all three levels: appearance, flavor, and waste. The green totes (method 4) faired the best with flavor being excellent, the appearance being unchanged, and the waste being less than 1 lb.  The plastic bags (method 1) seemed to have the least favorable appearance results, with root growth and sprouting all along the carrot. This required increased cleaning before giving product to CSA customers. While the flavor was fine, waste was 12 lbs, and overall time required was significantly more. Both sawdust and leaf mulch did not hold flavor well; the appearance was acceptable overall but did involve cloth wiping to remove the mulch residue. Although there was sprouting and root growth, it was less than with plastic bags.

For carrot storage New Leaf Organics will use green totes next year, but maybe smaller ones for ease of stacking and movement. They will definitely repeat post-harvest methods of spray washing and drying carrots thoroughly before storage. 

[download full farmer report]

 

3.  Rockville Market Farm: Post-Harvest Winter Squash Treatments

Rockville Market Farm researched post-harvest treatments for winter squash to increase storage ability and length of sales. Field-washed pie pumpkins, delicata squash, acorn squash and butternut squash were 1) untreated, 2) treated with Clorox bleach solution or 3) treated with StorOX, an approved hydrogen peroxide solution.

Results from this study were inconclusive. The wet 2009 season impacted the overall storability of some of Rockville Market Farm’s winter squash. Untreated delicata squash had the highest percent salable squash. A delay in weighing squash prevented determining salable weights of other squash types. Rockville Market Farm plans to continue this research to extend their sales of winter squash.

[download full farmer report and data]

 

These eight farmers have found farm-specific solutions that will impact their management practices and the viability of their winter growing operations.  Some participants will continue research on winter growing, season extension and winter storage to answer more questions on their farms.

 

Are you a farmer interested in participating in research like this? Please contact Lynda Prim at NOFA Vermont: (802) 434-4122 or lynda@nofavt.org