Juha-Matti Alakoskela

Hi,
I live in Finland, about 350 km north from the southern coast. This is also approx. 200 km north compared to Anchorage, Alaska, though thanks to Gulf Stream, throughout the year every month is approx. 1°C warmer than Anchorage.

Some a bit experimental Finnish nurseries offer typically a single variety of Cornus mas (Cornelian cherry), Elaeagnus umbellata (autumn olive), and Elaeagnus multiflora (goumi). These are typically rated for Finnish zones I–III (I is the warmest, Finnish zones are evaluated based not only on the coldest winter temperatures but also the number of days when the mean diurnal temperature is above 5°C and the growing degree days with the base temperature 5°C). I live in Finnish zone IV. I guess pretty much everything classified for USDA zone 3 grow here, and many but not all classified as growing on USDA zone 4 survive here (more or less all USDA zone 4 plants tend to survive on Finnish zone III though growth season might be too short to produce fruit). I have been thinking about trying some of them, nevertheless.

In many European nurseries there seem to be many cultivars of Cornus mas, Elaeagnus umbellata, and Elaeagnus multiflora available but also no information on the hardiness. Are there any significant differences in the hardiness of different cultivars, and if there are, what are the hardiest cultivars? Is there any difference between the species, which one is the three is hardiest and hence might be likeliest to survive?

If there are any other suggestions for other hardy fruiting plants I could try, those would be welcome, as well. I mainly interested in fruits and berries that can also be eaten as such, not ones that need 50% added sugar to make them palatable.
I have planted some cold-hardy apples and pears, some Prunus cerasifera (cherry plum/myrobalan plum), Prunus cerasifera x P. salicina hybrid (Kubanskaja Kometa) gooseberries, red(/white) and black currants, Actinidia kolomikta (mini kiwi), Prunus tomentosa (Nanking cherry), Amelanchier alnifolia (saskatoon/serviceberry),  Lonicera caerulea (honeyberry), blueberries, raspberries, strawberries, arctic brambles, and – because they are one of my favourites – I try blackberry cultivars that just tend to either die or barely survive but I will probably continue until all options have been tested. If someone has suggestions for an especially hardy blackberry cultivar (or a wild variant with tasty blackberries whose seeds are also obtainable) those would be appreciated.

I also planted Illinois Everbearing mulberry last year, and with some protection it survived first winter at least, though even if it continues to survive, because of the low number of growing degree days it might turn out to be Illinois Neverbearing here.

There is also a Prunus domestica and Prunus cerasus planted by the previous owner. I planted two fairly cold-tolerant Prunus avium (cold-tolerant for Prunus avium) cultivars this spring with Finnish rating I–III(IV) meaning that they should survive in zones I–III in general and in zone IV in a spot with good microclimate (the cultivars are 'Leningradskaja Tšernaja' or 'Leningrad Black' and 'Vytėnų geltonoji' or 'Vytenai Yellow'), though it remains to be seen if they survive. I ordered some seeds of Prunus mandshurica and Streptopus amplexifolia (twisted stalk) to try sow in the autumn. I am thinking of trying to plant black raspberry (Rubus occidentalis) and Prunus salicina next year.

I promise you that invasiveness is unlikely to be a big issue. Outside southernmost Finland the only foreign, invasive species producing edible fruits is Malus domestica or the common apple and even that is so rare that the only harm is that in most soutwestern parts of Finland where one endemic wild Malus species (Malus sylvestris) grows the feral Malus domestica is turning those into into Malus domestica x Malus sylvestris hybrids.

I have some in Lapua, Finland. Roughly it corresponds to USDA zone 3 or 4. Almost every winter there are some days down to -30°C, on exceptionally cold winters temperatures might go down to -40°C (but perhaps no longer with the climate change, since the last time it went that low was 27 years ago). Many USDA zone 4 plants survive here, but for some growing season is too short (in north-south direction I am located approx. 200 km north of Anchorage, Alaska, though thanks to Gulf Stream the average temperature in every month is about 1°C warmer than Anchorage).

Nanking cherries seem to be doing just fine here, though I have had them long. They seems to be favourites of hare, so one needs protect the parts remaining above surface of snow during winter. I had harvest for the first time from the Snow White / Snovit cultivar this year. They are far better than any Prunus cerasus fruit I have ever tasted. (I have one Prunus cerasus in the garden, and I do not mind they tend to be eaten by birds, since I do not like them.) The Nanking cherry fruits are extremely small, so there is little to eat in a single berry. They are neither quite so tart nor quite so flavourful than typical store-bought cherries (Prunus avium), but softer and I think sweeter, too. I think I prefer them to many store bought cherries, though best store-bought cherries are better.

I bought this year two supposedly cold hardy Prunus avium cultivars, Russian cultivar 'Leningradskaja Tšernaja' or 'Leningrad Black' and Lithuanian cultivar Vytėnų geltonoji or 'Vytenai Yellow', that should survive on Finnish zones I–III (I is warmest) and in good spots/good microclimates up to zone IV where I am located. Hopefully the microclimate I provide is good enough so that in a few years I can compare tree-ripened Nanking cherries to tree-ripened Prunus avium cherries.

I doubt that the cold will be a problem as such. (Though what might be a problem is if you have alternating warm and cold periods in the spring.) Actinidia arguta, including the Issai cultivar, survive just fine in Southern Finland (though the growing season tends to be too short so that many years the fruit does not ripen before the frosts). I had one in my garden when I was living in Helsinki (I guess in USDA zone classification that would be something like 5b, though of course that only considers the coldest temperatures, many plants that originate from continental climates with cold winters but also long, warm summers won't do well here or fail to bear fruit because the low growing degree days sum). If there is any problem with Actinidia arguta, though, you can switch to Actinidia kolomikta that also makes mini-kiwis and that survives cold temperatures (and shorter summers) much better. I have several growing even here in Lapua, Finland, where they survive just barely, but they do survive (not all cultivars, though). (The location is roughly 200 km north compared to Anchorage, Alaska, but thanks to Gulf Stream the mean temperature every month throughout the year is about one degree centigrade warmer than Anchorage.)

My favourite harvested wild berry where I live is artic bramble (Rubus arcticus) (it looks a bit like translucent red cloudberry but tastes far better than cloudberry). It is nowadays quite rare, and unfortunately the varieties sold in nurseries to grow in garden are nothing like the wild ones, as they as hard and tasteless. I simply cannot understand what went wrong in the recent domestication process. I also like wild strawberries but one rarely finds more than a decilitre of those in any given spot, and there is a bit same problem with wild raspberries. Billberries are quite nice, and if it is a good billberry year, it is easy to pick 10 litres of those in a few hours.
When I was in UK during my postdoc blackberries were my favourite wild berry over there. Here even the hardiest cultivated varieties can barely survive and even when they produce fruit they are nowhere near as good as British blackberries.