early Varietal Trials
Introduction & Pre-2014 Trials
Over the winter of 2012-2013, all potted plants were inadequately protected from the cold. Consequently, most died from exposure of the root systems to very cold temperatures. Those that survived are indicated by a “#” and are considered very hardy here at the farm. We continued to order plants throughout the winter, so we still had plants on trial during the summer of 2013. No plants that had already been planted in the ground died during the winter of 2012-2013, although they may have suffered extensive damage to above-ground growth.
General remarks: plants appear to need at least three years to fully acclimate. This includes ability to go dormant earlier than they are used to. Some varieties appear to be more adaptable than others (Wild Treasure, for example). Our short season catches most varieties still actively growing when the first frost occurs. For many varieties, this means that most new growth for the year is lost. Performance is related to vegetative growth, not productivity. Productivity will be noted. Grafted varieties (vinifera that are sensitive to phylloxera) are at a disadvantage, since common root stocks aren’t hardy enough and the graft itself is sensitive to cold.
We have trialed grapes from rooted vines, as well as cuttings. Rooted vines (like are offered in stores) have much more stored energy than cuttings (which I root myself). In general, both have yielded the same results: they live for 2 to 3 years and then die. This is most likely due to the fact that after three years the vines have exhausted their supply of buds from which to sprout. Grapevines must produce new wood (that “hardens” off in the fall) each year in order to continue to live. If no new wood hardens off before the first frost, the new growth dies. The vine then has to rely on old wood (from previous years) to produce new growth the next year. Each ҢudӠon a grapevine actually contains three small buds (primary, secondary, and tertiary buds). One sprouts each year, so after three years there are no more buds left to sprout and the plant dies (this was well demonstrated by Concord). Thus, it is critical that a grape variety be able to harden off wood each fall – a real challenge in interior Alaska where the season is too short and the change in day length is too rapid in the fall to trigger dormancy in plants (see Valiant).
Lack of heat (less than 1000 GDD (50F) typically; average = 750; range = 450 to 1070) limits vigor of all varieties. In 2013, we erected a high tunnel over newly acquired vines and this seemed to boost performance of some, but not all varieties. We expect that the use of high tunnels will increase the available heat to about 1300 GDD (50F) in a typical year. Varieties such as Baltica, Valiant, Edelweiss, and Osceola Muscat (ES 8-2-43) require 1150 to 1400 GDD (50F) minimum to ripen fruit.
Growing season is also a limitation here on the farm. Our elevation (1500 ft) tends to protect us from late summer radiation frosts seen at lower elevations, extending our growing season to around 125 days in a typical year. Of the varieties on trial, only Baltica has been known to ripen fruit in 120 days or slightly less.
Except for the 2012-13 winter season, all grapevines have been protected by burial either under dirt or snow. Thus, no canes have been exposed to midwinter air temperatures. From other studies and anecdotal data, it is unlikely that even the hardiest varieties (including Valiant) will produce wood that survives above the snow line in winter. While temperatures here at the farm only occasionally drop below -35F (-38C), other factors such as dryness (very low dew points and frozen soil for six months), duration of cold events (up to nine days), and fluctuating temperatures (-30F to +30F to -30F in 15 to 20 days) likely challenge the hardiness of typical Zone 3 plants.
Raspberries & blackberries: primocane = new canes that grow from the crown of the plant. Fluoricane = canes that have overwintered (develop a brown exfoliating bark). (E) = erect variety, (SE) = semi-erect, (T) = trailing variety, + = thorny, – = thornless. Almost all raspberry and blackberry varieties have been planted in the ground. Winter temperatures have not affected the crown/root systems of either (except possibly Logan), it appears. However, the canes have varying degrees of cold hardiness. None of the raspberries or blackberries were killed during the 2012 – 13 winter.
We allow all canes of trailing blackberries to grow on the ground the first year. This maximizes the heat they experience and minimizes their exposure to strong winds, which we occasionally experience during the summer months. It is also crucial for their survival during winter months, when snow cover keeps the ground (and berry bushes on it) above +20F. This year (2013) we planned to experiment with thick floating row cover as a protective layer, but time and 60 mph winds prevented us from doing so. Prior to the development of a 4-inch snow cover, temperatures dropped to 6F, with 9 inches accumulating before the first subzero temperatures. If possible, we will attempt to cover the trailing berry bushes next year. We also discovered that all semi-erect (SE) varieties could be encouraged to grow trailing canes if the canes are pinned to the ground when they are very short. We did this with Triple Crown and Chester and prevented all canes from growing erect, where they would not be protected by snow cover.
Peonies: Winter 2012-13 taught us a few things about peonies on the farm. They do not survive well in pots, although one Karl Rosenfield survived two winters in a pot in the past. We lost all peonies that were in pots. We also lost a significant number of peonies that were planted in raised beds. It appears that cold penetrated one foot into the sides of the beds that were exposed the most. Beds that are raised more than 6-10 inches above the ground are prone to freezing inward from the sides. Snow cover is an important part of protecting peonies in this climate.
Fruit trees: Except as noted below, all fruit trees and many fruiting bushes died during the winter of 2012-13. Some notable exceptions surprised us and told us just how hardy these plants are!
We attended an apple grafting class spring 2013 and successfully grafted 4 new-to-us varieties.
We added additional varieties for 2013. These varieties are followed by “(2013)”.