Ask Dave Jackson and Holly Laubach about the most important trait for a kiwi, and they’ll answer in one word — taste. That’s the reason these dedicated growers have concentrated on developing the best-tasting hardy kiwi from the start.
Kiwi Korners, Dave and Holly’s 40-acre central Pennsylvania farm dedicated to hardy kiwi production, began with a collection of about 50 named varieties from around the country and the world. As the couple worked on a breeding program to identify the best varieties for the East Coast, and they also experimented with management systems and developed a market for the fruit they refer to as KiwiBerries.
“I know a lot more now than when I purchased the place, especially about frost,” said Dave. “We were looking for a well-drained area that was up on the second and third tier from the valley to help protect from frost.”
But many of the kiwi varieties they obtained were mislabeled, and it’s impossible to tell males from females until they’re vining and producing flowers. Dave and Holly concentrated on dealing with only nurseries that were looking at kiwi as a commercial crop rather than a novelty.
Before they got serious about growing full-scale hardy kiwis, Dave and Holly planted kiwis in their backyard. About eight years into growing, Dave noticed the superior flavor of fruit grown on land that was untreated with commercial fertilizers or sprays, so they decided to obtain organic certification.
“We ran test trials and kept throwing out the varieties that didn’t work,” said Dave, adding that he recently dumped two collections of crosses that he started five years ago. “Most crosses don’t work well. You have to be on top of the genetics you’re looking for and hopefully, those will come through. It usually takes around 15 years to bring a new kiwi to the market.”
Although growing kiwis might look simple because of the rapid growth rate of the lush vines, there’s a lot involved. Most kiwi varieties are dioecious, so it’s essential to have the right combination of males and females growing within the appropriate range of each other. Dave and Holly have carefully placed male plants throughout the orchard so that prevailing winds carry pollen to female plants. Males at the end of rows are planted next to Paulownia trees (which are not invasive at Kiwi Korners’ location) for support.
The breeding process to develop new crosses is tedious, and includes bagging female flowers and bringing in pollen from specific males. Dave says this year, some of new varieties had a shorter flowering window — 5 or 6 days instead of 12 to 14 days. “That means that if there’s enough pollen out there in that condensed time, the fruit will be more uniform in size,” he said. “That’s another tweak we’re working on this year.” Dave says he’s also working on developing a self-fertile variety that is economically viable. “That would eliminate the need for males or pollen from the west coast. In a lot of cultivars, the timespan for flowering is up to two weeks, and during that time, a lot of male flowers are lost due to rain. If it rains two or three times, you can lose up to 70 percent of male pollen. That’s when we bring in back-up pollen from the West Coast. It’s very expensive, but it ensures that customers will have a product from us.”
As he learned about growing hardy kiwi, Dave tried various trellising methods. “The books all say to drape the plant to the ground,” he said. “We tried that and failed miserably. We couldn’t manage weeds, and sooty smudge was a problem. The further down the curtain the sooty smudge was, the more corrupted the fruit skins. We decided to trim the canopy for direct and indirect sunlight.”
Dave and Holly strive for pruning that allows optimal fruit production. “We prune back the top so light can come in, and continually prune back for next year’s spurs,” said Dave. “Light comes up through the bottom, brings blush and also increases brix.” Dave noted that accumulated pruned material is long and not safe to put through a grinder, so discarded vines are moved away from the arbor and burned. The other issue with a long, draping canopy is deer damage, so Dave refers to his pruning and trellising as ‘above the browse line’. Because kiwis grow rapidly, Dave and Holly are constantly pruning back new growth to allow light and air into the canopy. The downside to heavy pruning is wind rub that occurs with summer storms.
To propagate and work on new varieties, Dave takes softwood cuttings in early July and places them in a 50/50 mix of vermiculite and perlite. In about 45 days, new plants will have grown as much as a four-inch root ball. Young plants in the nursery area are spaced two feet apart and trained to poles, and Holly is constantly working with the main canes to keep them from twisting around the poles. After several years in the juvenile area, the most vigorous plants are transplanted to a permanent block. Irrigation throughout the orchard supplies the moisture needed for good fruit production.
Dave uses a vineyard hoe mounted on the rear of a tractor to turn the soil on the rows. He says this is the best method of keeping the rows weed-free. Grassy areas between rows are kept mowed to help ward off disease. But the ongoing job at the arbor is pruning.
Harvest begins in September, and harvest planning is a matter of determining optimum ripeness, potential frost and dodging insect pests that appear in late summer. Dave is considering hiring a professional blueberry picking crew for more efficient picking.
One of the two varieties Kiwi Korners offers to the commercial market has a consistently higher brix level than any other kiwi on the market. “It was our passion to put out this popper, so it’s called ‘Passion Popper’,” said Dave, noting that the variety took 14 years to develop. “We also have ‘Aloha Anna,’ which has overtones of mint and pineapple.”
Dave guarantees a 21-day shelf life for Passion Popper. “You can’t have that shelf life without extremely high brix,” said Dave, adding that Passion Popper consistently measures 28 brix. “The lower the brix, the lower the shelf life. To us, brix is just about everything, especially if you’re looking for return consumers.”
As Dave and Holly fine-tune their management protocol and new crosses, they’re constantly striving for improved cultivation methods that will produce the best kiwi for the market.
“We’re combining genetics and management,” said Dave. “When you put those two together, it works.”