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Organic Technology at High Altitude Rhubarb
 We have pioneered a unique organic growing technique that obviates weeding, conserves water and minimizes the need for soil amendments beyond the initial preparation. The technique has proven extremely successful since 2002. This page will explain that technique and the results. We've used no chemical fertilizers since 2002. We've never used pesticides. Our operation began non-organically. However, our current organic approach produces sizable harvests, yielding about 15 pounds per plant in the initial harvest and half that for the second harvest. Our technique requires considerable labor and cost to establish but very little to maintain. The other benefits include lower water requirements than non-organic approaches and virtually no weeding required. During our non-organic startup we found that our soil required considerable amendment. It was overgrazed to the dirt by horses. The soil was high altitude prairie grassland, compacted and barren of all but weeds with some grasses and wildflowers struggling back. Our native soil is "Kettle-Pring-Peyton association: Deep sandy loam and loamy sand soils on arkosic sandstones."1 The top soil was only 1-2 inches thick and an odd mix of clays and sand. The initial beds were prepared in 1995 in a non-organic manner. First, 3" of compost was tilled into the top 6" to 8" of soil and this  was further amended with sufficient high nitrogen fertilizer for beds 10 times the size of our beds. The beds were then broadcast watered throughout the growing season. Weeds and grass germinated but were promptly killed by the high nitrogen concentration. The beds went fallow. The following year the soil was tested by the Colorado Extension Service. They reported they had "never seen such ideal, rich soil but it was rather high in organic material." For the next several years the soil and plantings, which included 12 rhubarb plants, were maintained in a non-organic manner...chemical fertilizers were used twice per year to  bring in high yield harvests of a variety of crops suitable to our area, including corn, beans, peas, squash, basil, carrots, potatoes and garlic. Organic growing of rhubarb began in earnest in 2002. About 50 plants were planted from an original 12 plants via root propagation. The unique aspect of our technique deals with soil preparation and composting. With our technique there is no need for spreading large amounts of compost, additional soil amendments or weeding. Soil preparation went as follows: 1) The soil was heavily amended with mature compost, tilled into the top 6"-8" of soil. Then the amended soil was piled into small buttes, each about 1.5' tall and 6' apart, center to center. (see photo to right) Then a new rhubarb root was planted in the center of each butte and a water ring was formed on the top. The area around the perimeter of the beds was then covered with a 4' to 5' strip of landscaping fabric to form a barrier to surrounding plant roots and seeds. Then the fabric and the beds themselves,  between the buttes, were covered with 2' of ponderosa pine mulch, locally available at low cost. The deep mulch, combined with the rhubarb leaves themselves, makes it virtually impossible for weeds to grow in the beds. Any that do are easily pulled by hand or ignored as they have negligible impact on the harvest. Earthworms were also added to the soil around each plant. They appear to remain in large numbers years later. The area surrounding the beds is kept mowed to prevent any seed production within 20-40 feet of the beds...and for aesthetics. The mulch composts in place and thereby provides the lion's share of plant nutrients. Some of the compost leaches into the soil around the plants and some provides a home for future root growth. You don't want the uncomposted mulch mixing in quantity with the soil. This would bind too much nitrogen in the bacteria decomposing the mulch. Nevertheless, soil and compost gradually erode from the buttes to mix with the composted mulch and small amounts of uncomposted mulch, adding to the surrounding soil base. In our semi-arid climate the mulch must be topped off with another 3"-4" of mulch about every 5-6 years. (Semi-arid: 13" of rainfall-equivalent per year.) It would probably be more frequently in a wetter environment. The mulch  not only continues as a weed barrier and constant source of fresh compost but it also helps with moisture retention in the soil, considerably decreasing the frequency and volume of water applications. In our semi-arid environment our supplemental watering has never exceeded 10 gallons per plant in one year...and we've had some very dry years. In the fall, right after the plants have gone dormant, we cover each plant with 1"-2" of mature manure compost and water this in. This helps the plants winter over and provides a nutrient boost in the spring. As the first plants appear in the spring we pull the compost back to form a new water ring around the plant on the top of each butte. (see photo of new growth) This additional compost is small...about two shovels per plant per year, but serves to raise the top of the buttes to compensate for natural erosion. As the buttes rise and the surround mulch composts, the buttes begin to protrude above the mulch (see water rings  photo). Therefore, after 5-6 years it is necessary to top off the mulch with another few inches of fresh mulch. This provides continued food for composting and ensures an uninterrupted and even cycle of plant nutrition and growth. Additionally, walking through the rhubarb fields is an aesthetically pleasing experience. They are not only pristine in appearance but the deep mulch creates a very cushioned walking experience and makes it easier to get on your knees.  Much of our moisture is in winter snowfall and yet each plant normally nees only 1-2 gallons of water 6-7 times per year for large harvests (total of about 10 gallons per year). The resultant plants are large and healthy, producing about 15 pounds of rhubarb per plant in the first harvest, around May-June, and about 7 pounds per plant in the second, about 6-8 weeks later. We've used this technique successfully since 2002 and feel confident it will prove effective in the long run. Yet to be determined are the possible need to replant the mounds over long periods of years. Normally, rhubarb fields are replanted every 5 years. We have passed that mark by one year without any need for replanting. Time will tell. We will gladly answer any inquiries and assist anyone in adopting a similar approach in their own beds. Just contact us. 1: According to the U.S. Department of Agriculture, Soil Conservation Service |
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