Haygrove High Tunnels – Control of Nature?

by Gary Mount

The two basic resources that a farmer has to work with are the soil and the weather. And one of the most “interesting” aspects of farming is its relationship to the weather. Severe weather takes its toll on farm crops-with too hot, too cold, too much or too little rain, and high winds-lots of things can happen. And, except for a few techniques, there is little the farmer can do. At Terhune Orchards, we have a 5,000 square foot greenhouse that provides a protected growing environment all year. We also protect our strawberries from frost on cold nights in the spring by spraying water from our irrigation system over the field.

This spring we are working on the largest and most challenging crop protection technique ever. As I write this, it is not quite completed, but I am already getting questions. “What are you building out there? It seems to be near the cherries? Are you still going to have pick-your-own cherries?” The answer is, yes, it is near the cherries. In fact, it is over the cherries. The structure is called a Haygrove High Tunnel. I purchased it from the Haygrove Company of Herefordshire, England and its purpose is to protect the cherries from my friend and nemesis, the weather.

Many of Terhune Orchards pick-your-own cherry customers have seen the devastating effect the weather can have. During the cherry ripening period, which is the final two weeks before harvest, the cherries greatly increase in size. That is, the cells in the cherry are expanding so rapidly that the skin of the cherry can barely keep up. Its size has to increase rapidly as well. If, during this time, a significant rainfall occurs, disaster strikes. The cherries absorb the raindrops, causing even more cell expansion and even larger cherries. The skin can’t keep up and cracks develop, making splits in the cherry. Decay starts in the exposed areas of the flesh of the cherry-an unattractive and unappealing mess. Three years ago, we had three days of rain before cherry harvest, and 100% of the cherries cracked. Not one was picked! Just awful, a total loss!

Enter the Haygrove Tunnels. Right now, halfway through construction, there are just rows of high metal hoops over the cherries. In a week or two we will cover the hoops with clear plastic covering and hold it down by an arrangement of criss-crossed ropes. In times of high temperature or strong winds, the tunnels can be vented by pushing up the plastic towards the top of each tunnel. Later, the edges can be pulled back down as needed.
Since we started working on the tunnels, I have also realized that they can protect the cherries from frost during bloom. That’s a pretty good thing, since the cherries bloom early and the blossoms can sometimes freeze, which means no fruit. Another thing the tunnels might do is to move forward the date for picking the cherries. The way this works is that we could cover the cherries early and raise the average temperature under the tunnels in the spring.

One of my fruit-growing friends in California, Steve Blizzard, did this recently. As a grower in California, he does not farm in acres, such as our two acres of cherries. He farms in hundreds of acres, as do most California farmers. Steve’s cherry orchard is very large and his crop is packed and sold wholesale, with most of the cherries exported to Asian or Pacific Rim countries. In such a marketing plan, having your cherries come in a week or two early gives you a significant advantage. Steve’s location is not so susceptible to spring frost or pre-harvest rain. But getting his crop marketed early has really paid off.
At Terhune Orchards, I am thinking that bringing the cherries in early might not be the best idea. Right before cherry time is pick-your-own strawberries. It might be better not to have everything at once.

This year, at least, we will concentrate on rain and frost protection. The Haygrove High Tunnels will cover half of our two acres of cherries. Pick-your-own cherry harvest will be the first or second week of June. Check our website, terhune.flywheelstaging.com, or call the farm in late May for a more exact date and come check out those Haygroves!