By Lee Stivers
Carrot transplants are grown in large quantities in Italy. They must be transplanted before the taproot reaches the bottom of the tray cell.
Before the widespread use of plastic mulch, drip irrigation, high tunnels and greenhouse production, there seemed to be a clear line of demarcation between vegetables that could be transplanted, and those that had to be seeded directly into the field. Grower innovations have nearly erased that line.
We've always "known" that tomatoes, peppers, cabbage, onions and lettuce could be started early in the greenhouse, and then transplanted into field or garden, while many other vegetables crops, such as sweet corn, beans, beets and carrots, had to be seeded directly into the field. But times change, and fortunately, farmers don't always do what they are told. I encountered my first field of transplanted sweet corn in western New York in the early 1990's, growing strong and vigorous with no signs of transplant shock. Next came vine crops; growers were starting not just melons but cucumbers, squash and even pumpkins in the greenhouse and transplanting them to the field.
In 2005 I visited a farm where beet seedlings were transplanted into plastic-mulched beds with drip irrigation. More recently I have found growers transplanting early peas and beans, along with annual herbs and specialty leafy greens. I wondered: which vegetable will we be transplanting next?
I received an email from a grower in Italy last month with an answer to that question. According to Giorgio Rampinini, large quantities of carrot transplants are produced and sold in Italy. Growers have found that carrot seedlings can be successfully transplanted as long as they are removed from the tray before the taproot reaches the bottom of the cell. If the taproot grows to touch the bottom of the cell, the carrot will end up forked and branched. If the seedling gets planted into the field before this, the carrot grows straight and true.
Perhaps the next challenge to growers is figuring out a way to successfully transplant radishes. Considering how quickly they go from seed to harvestable radishes, this could be tricky indeed.
Transplanting vegetables rather than direct seeding them is a very useful strategy for controlling weeds and for getting an early start on the growing season. Fortunately, growers have found innovative ways to push the boundaries on which vegetable crops can be transplanted.