Kiwis on the extremes

In the comments on a recent message, Brandon mentions wanting to grow kiwis in Florida. Most commercial kiwis are 'Hayward'--but 'Hayward' requires roughly 800 hours of chilling (time between 32° and 45°F). That's probably nearly twice what Gainesville (where he is) is getting.

There are many low-chill varieties, though. All of the following are described as requiring 250 or less chill hours:

Vincent—Produces large crops of smallish brown fruit
Dexter—An Australian variety, medium in size, slightly elongated, quite hairy
Abbott—Small to medium, oval, dark brown, long, dense hairs
Allison—Similar to 'Abbott'
Elmwood—Extremely vigorous, produces large kiwi-shaped fruits.
Bruno—Large, long, cylindrical, dark brown, with short, dense hairs. Light green flesh, good flavor.
Monty—Small to medium fruit, large yields, very late
Tewi—A lower chill seedling of 'Hayward', which it resembles.
Blake—Early maturing, low-chill, and teardrop shaped (supposedly, though I have to say some of the pictures I've seen don't really look it).

Since kiwis require pollination, you'll need to find low chill male, too. Some nurseries will just sell home growers male seedlings, but that's a little risky, because you never know what you might be getting--there's always a chance it won't bloom at the right time, or be horribly disease sensitive, or, in the case of Florida, be too high chill to bloom properly at all. It's probably worth the investment to get a named male cultivar. 'Matua' is that one I most commonly see mentioned for low-chill areas, but Chico No. 3 may work better for really early females.

On the other end of the spectrum is the hardy kiwi (Actinidia arguta) and the "arctic" or "superhardy" kiwi (Actinidia kolomikta). These species can grow in places too cold for the typical kiwis, surviving temperatures down to -25°F, in the case of A. arguta, and -40°F with A. kolomikta. Hardy doesn't necessarily mean winter-proof: hardy kiwis can easily be fooled into breaking bud early, and are sometimes victims of spring frosts.

The fruit isn't what we usually think of as a kiwifruit--a bit more like a grape than a big fuzzy egg, but the flavors are fairly similar, and with relatively thin, fuzz-less skins, you can pop them in your mouth without peeling. Since they don't fit the standard kiwi mold, there have been attempts to market A. arguta under a range of other names: piwifruit, bowervine, tara, yang-tao; but none of these seem to stick.

Some A. arguta cultivars include:
Ananasnaya—A Russian variety whose name means "pineapple-like". (Because hardly anyone who isn't Russian can say the name on the first try, some nurseries call this 'Anna', which is easier to deal with but nowhere near as exotic sounding. Probably the most common variety, it's flavorful and vigorous. There's also a Russian A. kolomikta cultivar under this name, just to confuse things.
Meader—Although I don't know for sure, I'm assuming this was bred by New Hampshire breeder Elwyn Meader, who probably deserves a post of his own one of these days. Supposedly it is available as both a male and a female, which strikes me as odd--I have to assume there are just two different vines with the same name.
Geneva—Supposedly this was propagated from a vine at the NY State Experiment Station in Geneva, NY. I'd like to think this was the female vine growing on the building next to mine when I was there. It very well could be...the only other hardy kiwi there was the male next to it (until the male died). If it's the same thing it's got good flavor and fairly low yields. 'Geneva' is also reported to be a fairly early cultivar.
Issai—A Japanese variety notable for being self-fertile. If I was a hardy-kiwi breeder I'd be all over this one. It's far from perfect, though, as the fruit is small, the vigor is low, and the ripening quite uneven. I've also heard the flavor is uninspiring, and that it's slightly less hardy than some varieties of A. arguta. There are probably at least two self-fertile varieties bopping around under this name.
Ken's Red—Most notable for being, not surprisingly, red. Actually a cross of A. arguta and A. melanandra. Cherry-sized red fruits, sort of squarish.
Dumbarton Oaks—Found on the grounds of Dumbarton Oaks, a Washington, D.C. research institution. Purported to be another early cultivar.

There are assorted males around, but A. deliciosa pollen works for A. arguta so you can double up if you're growing both.

A. kolomikta hasn't been bred much, so the cultivar selection is limited. It's sometimes known as "super-hardy kiwi" or "Arctic Beauty" and is notable for it's incredibly high levels of Vitamin C--20x higher than a similar volume of citrus. Fruit is smaller than hardy kiwi and the vines are harder to establish. They can make nice ornamentals, considering that many have an interesting pink variegation.

Only a couple cultivars are readily available:
Krupnopladnaya—Another beautiful Russian name, this one means large fruit. It's all relative—these fruit are big for A. kolomikta, but not in the general world of kiwi. Generally good and sweet, kind of low in vigor.
Pautske—Good quality, more vigor than Krupnopladnaya.

One Green World has quite a variety of kiwi cultivars, hardy and not (though they don't seem to have any of the low chill ones--they're based in Oregon, after all), though they have what I consider the annoying habit of renaming many of the Russian cultivars and not giving the real names, making it difficult to know anything about what you're buying beyond what they tell you. (The also call all the kiwis Actinidia polygama, which rubs taxonomy geeks like me the wrong way). Still, they've had a pretty good track record with me, and the offer most of the higher chill varieties listed here, and a few more. I don't know a source for many of the low chill varieties (mostly because I haven't spent as much time in low chill places), but Top Tropicals has Vincent, paired with a pollinator, Tomuni, and Rolling River Nursery has Elmwood and Blake as well as some hardy kiwis.

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A mountain of kiwi genes

Scientists from Hortresearch in New Zealand have just released a serious pile of genetic sequence data from kiwifruit (Actinidia deliciosa). 130,000 ESTs, to be exact. (EST stands for Expressed Sequence Tag--this is sequence from individual genes that are being expressed at the moment the extraction took place, transcribed from the mRNA.) This has to be among the largest single releases of sequences for a horticultural crop. Kudos to them for sharing with the rest of us. (Of course, really, who else is doing enough kiwi molecular genetics work to use this besides the New Zealanders?)

Scientists detail kiwifruit genes (Business Day)

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