Dual Season Organic Asparagus Production

Asparagus crowns were purchased from two northeast (US) wholesale asparagus crown farms. These were not certified organic crowns. Because of the timing of the grant award, we could not place an order in time before the organic crowns had been sold out from the available organic vendors.

Consulting with our extension agent Shawn Jadrnicek who in turn consulted with Dr. Robert Dufault from the Clemson University Experiment Station, we determined the best variety for the area. Clemson University had just completed test plots at the Coastal Experiment Station near Charleston , South Carolina, therefore there was excellent research data on the best varieties for the coastal zone. The supplier was consulted as well for their opinion of the best varieties for the area.

Several selections were made in accordance with recommendations from both our grant contributors and the vendors themselves. Also, the selected varieties were chosen to accommodate differing production schedules for anticipated clientele.

While some organic crowns were available at the time the order was placed, they were not the varieties sought for the project or suitable for area’s climate and soil conditions Since there were no available sources for organic crowns meeting our requirements (at the time of the program start), we purchased conventional crowns. Because the crowns would be managed using organic methods over one year before any harvest would take place this was deemed to be acceptable.

Although purple varieties were not recommended by the researchers, we chose to place one forth of the area in purple asparagus because of our own experiences with colored varieties of produce which anecdotally had produced good resistance to insect pressures. Additionally, colored varieties have added market value. The varieties chosen were Jersey Supreme, Purple Passion, and Jersey Giant.

After the grant award, we began evaluation of empty fields for potential locations for the project noting potential problems or advantages of each field. All of our potential fields had been certified organic for two previous years.

After comparing fields it was decided to use the daffodil field in which we had begun removing bulbs for relocation two years ago. This field had the best soil structure for asparagus and the least amount of grass. It had very little Bermuda grass. It did have centipede but this type of grass is much easier to control than the Bermuda. Also, there is a hose bib nearby which could be used to expand irrigation.

We began removing the remaining daffodil bulbs from the field. Two additional workers were hired to assist us with this task we were able to completely clear the field of the remaining bulbs estimated to be about 6000 bulbs.

The field was plowed with a sub-soiler. The field had been grown up with small trees, mostly gums mixed with the daffodils, but mowed down annually. These had very large root systems even though the trees were merely bushes. Roots were picked up and taken out of the field. The field was then plowed with disk harrow.

The field was next tilled with rotary tiller. A bowl became evident and this was corrected using a blade to crown the field to make drainage flow to the ends of the fields.

The soils test report indicated the need to add lime to correct the pH. Lime was spread the at the recommended rate (1700 pounds per acre) to the project site using a rotary fertilizer spreader (spinner). A rotary tiller was used to incorporate lime into soil.

Coastal soils are naturally high in phosphorus. The other recommendation was for potassium. This was not applied until after the crowns had been planted due to the difficulty of obtaining a source suitable for organic production. Fertrell’s SeaK was applied later in the year. Boron in the soil was adequate from the soil tests.

A cultipactor was used to lightly compact soil before making trenches to receive crowns. Trenches were made with a middle buster approximately 8 inches deep (from level ground). Fertilizer was added to trench bottoms. The fertilizer should be wetted before plants are placed. Since it rained, we were able to skip this step.

Fertilizer used was a Perdue chicken manure based product 4-2-3 applied at the recommended rate per the soils test. Tissue tests revealed adequate nitrogen in the plants. The first year plants seemed to be growing well, but pressure from deer was beginning to take a toll and the plants were not gaining strength and size to our satisfaction. In the second year of growth, major deer pressure made it impossible to consider harvest for sales. Soil samples for the second year showed adequate nitrogen but inadequate boron. Boron was applied in December of 2010. Perdue Chicken manure based fertilizer was again applied in December 2010 (900 pounds)

The area is approximately one half acre and the recommended nitrogen for establishment is 100 pounds nitrogen per acre or 50 pounds per one half acre. Recommendation for Potassium is 150 pounds per acre or 75 pounds for one half acre, 14 bags were applied to 30- 130 foot rows at initial planting. This is 700 pounds of fertilizer or 28 pounds of nitrogen, 21 pounds of Potassium, and 14 pounds of phosphorus. Subsequent applications of fertilizer will cover the deficit.

In the weeks of April, the sprouts from the crowns began to emerge and it is estimated that about 95% of the crowns produced a viable stem. These progressed adequately for the coming months and some deer did eat some of the plants, but pressure was not heavy.

Day laborers were hired to weed rows. The most common were ragweed, crotalaria (rattlebox) and dog fennel. Weeds were allowed to grow much larger than they should have which made for very difficult weeding. It took about 6 days of crews of 4 to completely weed the crop. After that, occasional day labor when workers could be found were used along with our own in-house labor for weeding.

Throughout the fall of 2009 we continued to weed. No fertilizers or amendments were applied. After hard frost and freeze, we were able to mow down still-living plants. Some had died but many remained green until a hard freeze. A flail mower was used for mowing.

During the winter of 2009 above average rainfalls hampered the ability to cultivate. We were able to cultivate once in December after mowing. In January of 2010, rains flooded field for about 2 weeks.

In February 2010 the fields were fertilized with 350 pounds Perdue 4-2-2 organic fertilizer (chicken manure base). This was applied with a fertilizer hopper directly over plant stem. By this time we had located a suitable potassium supplement and we fertilized with 500 Sea K from Fertrell which is a 0-0-10 (organic) applied with a spreader (rotary).

Following this we began a heavy mulching with composted wood chips over stem locations. Weeds again were controlled by hand weeding. The mulching was very helpful for weed control in the following summer months. Although there were weeds, there were less than the previous year and more easily removed.

Tractor cultivation removed weeds from between the rows. A Williams tool cultivator with sweeps and spiders was adequate for this. Hand weeding was required to remove weeds close to plants.

For the second year, we anticipated being able to harvest at 10% (10% in the fall and 10% in the spring) as recommended. However, intense deer pressure prevented any harvest and the plants suffered dramatically.

We decided to harvest none of the plant fearing that we would damage what little was remaining. We made plans to fence the field in the fall. We continued to pull weeds from the plants.

In late summer, we opted to mow one half of the field to determine the viability of a fall crop in the following year.

After mowing, the fall crop emerged. It took approximately 2 or 3 weeks to have stalks that were harvestable. Again, deer came and ate all the harvestable stalks before we could.

In the latter part of summer 2010 tissue samples were again taken. All elements tested were within acceptable limits except boron. While boron was present in sufficient amounts from the soil tests, it was not being assimilated properly in the plant. Boron is an essential limiting nutrient in asparagus. After consulting with Clemson University staff, they recommended application of boron. Because of the excess phosphorus in our soils, boron was not being taken up properly by the plants.

In January of 2011, we applied 900 pounds Purdue 4-2-2 fertilizer to the rows. We also applied the boron at the same time in the recommended rates.

The part of the crop which had been mowed in late summer had additional weed pressure from perennial grasses. In the spring that followed, noticeable differences in the summer mowed crop were apparent. The spring 2011 stalks in this side were smaller in diameter and less vibrant.

By the time the spring crop was ready to emerge in 2011, we had installed a high welded wire fence to protect the crop. We decided not to harvest any of this spring crop but to allow it to grow throughout the summer to repair the damage from the deer in the preceding year.

The 2011 spring crop is vibrant and lush.

• Photo of Grass in Field Prior to Field Prep in 2009
• Fine Soil Preparation Before Planting Crowns
• Tractor making trenches for crowns (March 09)
• Initial fertilizer application at planting (March 09)
• Tractor and toolbar covering crowns in trenches (March 09)
• Watering in the crowns (March 09)
• Cultivator set up in January 2010
• January 2010 after cultivation
• January 2010 mulching
• March 2011 Asparagus Crop
• Plowed Field during root removal operation
• Wade Coleman and Sam Connor placing crowns in trenches (Mar 19, 2009)
• Close up of crowns laying in trench (March 19 and 20, 2009)
• Extension Agent Shawn helps plant crowns
• Field Prep showing some of the underground roots removed
• Emerging Crowns in April 2009
• Multiple trenches ready for planting crowns (March 09)