Experimental Dwarfing Pear Rootstocks

I’m a keen hobbyist growing pears in a very harsh central Alberta climate. How harsh? -42C has been my coldest. My average winter low is -37C. This winter for example it hit -38C in late December as the coldest. So the rules for growing pears for me are 1/ They must be able to survive -40C. 2/ They must be able to survive -40C 3/They must be able to survive -40C. There are a few more main rules, but I bet you can guess what they are :slight_smile:

I have experimented with several pear rootstocks, and the following are my comments:

Siberian Pear, Probably the best all around rootstock for my area. It does not show any incompatiblity issues with the pears I grow, basically of Russian origin. These all have Ussurienses (Siberian Pear) in their ancestry. This is a very hardy rootstock, and makes a full sized tree ultimately.

OHxF87, OHxF333, OHxF97 These survive fine due to the aways decent snow cover we get up here. The problem is these rootstocks are always imported from the USA, and to get into Canada the roots are heavily fumigated. This literally means 4 out of every 5 of these rootstocks die on me the first year. I suppose if there was a Canadian supplier this would not be a problem. But the 20% that survive the fumigation seem to work well.

Saskatoon This is the ONLY rootstock I have found so far that actually gives a bit of extra hardiness to the grafted pear scion. I use Smoky Saskatoon, which grows to about 12-14 ft. tall. The grafts MUST be done at chest height, as strange as that might seem. Grafts near the ground take, but then die in a year or two. Why? Part of the great unknown…The pears are full sized and of normal taste. You graft onto trunks of the Saskatoon that are about as thick as your thumb, usually a bark graft, and at chest height. The only problem is the way Saskatoons grow. The trunks only last a few years, then they die, to be overtaken by new shoots coming up from the roots. My oldest pear grafts on Saskatoon are about 8 years old so far, and they may last 10 or so years. Naturally when the trunk dies, there go your pear grafts.

Cotoneaster (lucidis) This is the very common hedge plant grown in zones 2 and 3. Tests in Russia show long term compatibility with pears, 60 years and still going strong. However you MUST graft a foot or so above the ground and allow 2-5 branches of cotoneaster to grow directly under your pear graft. Why? Because the pear is great at sucking up nutrition from the cotoneaster roots, but pretty poor at sending anything back down. If you don’t allow “feeder cotoneaster branches” to grow, the roots don’t get fed properly, and in a year or two the roots die. You get an 8 ft. tall pear tree ultimately using cotoneaster as a rootstock. Fruit is normal in every way in terms of size and taste.

Aronia Berry The benefits are extremely early fruiting, sometimes one year after the pear graft is made! The downside is this is not a long lasting union, perhaps 3 or 4 years max. However Aronia is used as a rootstock in Russia to “speed up fruiting of new pear varieties”. I only grafted a few varieties of pears to aronia last year. All the grafts took and look good! Too early to tell if I will get fruit the first year after grafting. The only purpose I can see to grafting pear to aronia berry is you get to taste the pears in 1 or 2 years from grafting, vrs years longer grafted to other hosts. And you will have to be philosophical when the graft fails in 3 or 4 years due to longer term incompatibility.

Hawthorn and Mountain Ash. All my pear grafts experimentally to either hawthorn or mountain ash take really well and grow great, the first summer that is… Then for some reason they simply do NOT leaf out the next spring. Perhaps it is my cold winters, or perhaps the varieties I’m using are not compatible for the longer term.

Pears growing on apple trees via interstems. I have done a fair amount of experimenting with growing pears on my hardy zone 3 apple trees via a Winter Banana or Palmetta (an apple crab bred in Novosibirk, Siberia, extremely hardy) interstem. Again they all take very well and grow normally, actually better than normally, the first summer. However half don’t leaf out the next spring, and the other half only last two years. The longest lasting has been 3 years. My guess is my severe winter temperatures somehow damage the graft union, and this is why the interstem fails on growing pears on apple trees. I understand in more mild climates pears can be grown on apple trees via a Winter Banana interstem, but this doesn’t work in my climate. While I still graft pears to my Palmetta apple crab and they do very well the first summer, I only use this to grow scions and I harvest them in November and store in a buried 5 gallon bucket over the winter. If I harvest the scions in late March, often they are dead.

14 Likes

hi Bernie.im in z3b/4a here in n. Maine. last winter we got to -43f 1x and -40f 2xs in jan… i have a 6ft. mountain ash ive grafted 6 z3 hardy fedco pear scions to. all have taken and put out 2-4ft of growth last summer. as soon as i can get to it ill let you know if they all survived these temps. a few of my apple scions that were only z4 hardy didnt make it like Cortland and mac but the y. transparent they were on came through fine as did all my M. alba mulberries. my bush fruit should all be ok as they were completely buried in snow. i also have a shipova grafted on aronia in 3rd leaf. its only put on 12in. of growth in that time. last spring i planted ivans beauty hybrid mtn. ash/ aronia. came as a 5ft. tree and put out about 16in. of new growth last summer. im going to try grafting shipova and a few pears to it to see how it does.

3 Likes

There are some pear grafts onto Mountain Ash here in central Alberta that have lasted for years and fruit regularly. Unfortunately it doesn’t work this way for me. My conclusion is you have to be lucky to get a mountain ash/pear variety combo that is compatible for the longer term. They exist for sure, but for me its way too “hit and miss” to continue grafting pears to Mountain Ash in my area. Hopefully you will have long term compatibility, which is certainly possible. Good luck on your experiments!

3 Likes

Good to ‘see’ you, Bernie. I remember you from the old GardenWeb forums (pre-Houzz), back in the late 1990s.

5 Likes

Whiffletree sells OHxF87. I would imagine they grow their own.

2 Likes

FloraMaxx is Canadian and advertise that they sell OHxF87 rootstock.

4 Likes

@Bernie

Good to see you here again. I’m in some other groups with you as well. Gave you some pear grafting photos to use in the Alberta group years ago. Hope all is well with you.

Nope, Whiffletree gets their OHxF87 from a major Canadian Ontario wholesaler who brings them in each spring from the USA. So the fumigation problem concerns remain if you buy from Whiffletree (and I have). I have yet to find a single Canadian nursery who breeds their own OHxF87 or 333 and does NOT bring them in from the USA. If anyone knows of one, please comment. Lots of nurseries will sell these pear rootstocks in Canada, but ALL are imported from the USA and have severe death percentages of up to 80% due to the fumigation they must receive to cross the border.

2 Likes

Numbers of Canadian nurseries sell these rootstocks, but ALL are imported to Canadian wholesalers from the USA, then to the individual nurseries. Its not a problem to find nurseries that sell these in Canada. The problem is getting them made in Canada and sold to Canadians so they do not have to go through the fumigation of the roots required to import them from the USA (which seems to cause about an 80% mortality rate)

Things are good here, waiting for spring. Still hitting lows at night of -11C or about 10F, but temperatures should be warming up next week finally. Normally I can start grafting outdoors the last week in April, but this is a cold and late spring so far, so probably not until the first week in May this year.

2 Likes

I’m fairly certain that FloraMaxx only sells tissue culture plants so that wouldn’t be an issue. I just checked their order form and don’t see an option for OHxF87 despite them advertising it on their website. It was on the form last year.

2 Likes

I’ve purchased OHF333 rootstocks (among others) from Whiffletree Farm & Nursery in Elora ON & I’ve never lost one. (I bought a bundle of 25 a few years ago & another bundle of 25 last year.)

Either they weren’t fumigated (Canadian grown?) or the process didn’t harm them. (They use these same rootstocks to graft their own trees, so there’s no issue with fumigation.)

They have a phone number & they’ve always been helpful. ie The “automatic” shipping charges were astronomical but he actual shipping costs were lower because rootstocks are cheaper to ship than trees (shorter).

I’m putting this out there because I know from experience how hard it is to find decent & affordable rootstocks in Canada.

3 Likes

I’m glad your pear rootstocks all survived from Whiffletree! I spoke with Lawrence Martin a few years back, the owner, about the poor results of the pear rootstock with most dying when they come to Alberta. I told him about the fumigation problem and suggested he only buys “2 year old pear rootstock” from the wholesalers, ie pear rootstock that had been planted in the field for a year. This way he is assured of getting and selling healthy OHxF333 and OHxF87 as any damaged by fumigation would not survive the first year. My guess is he took my suggestion if you got 100% survival on the ones you got from him. Whiffletree is a first class outfit, very honest, great products and prices and I highly recommend them.

4 Likes

I see you are familiar with Siberian Pear. I have a 45 year old tree that I started as a seedling from a tree labeled “Siberian Pear” growing in an arboretum. This was before I knew anything about Bradford Pears (callery). Since then, I’ve seen these ornamental pears and can’t tell any difference from my tree, even though they are supposed to be two different species. Do you know any distinguishing traits I could use to see a difference? I’m beginning to think that the mother of my tree was mislabeled. Thanks.

1 Like

Hi Bernie, I’m waiting for another bundle at the end of the month & I’ll post pics as soon as they arrive. The previous ones which I had such good luck with were definitely 1 year old & I’m assuming these ones will be, too, because (surprisingly enough) the price hasn’t changed much since last year.
I hope you haven’t jinxed me (I’m kidding.) Please keep your fingers crossed for me & I’ll post pics soon & I’ll let everyone know how this lot does , over the year.

Bradford pear won’t survive up here as it is zone 5 at the best from what I have read. I am zone 3, zone 2B in a test winter. So I can’t comment on it from personal experience. But Siberian pear is light grey in colour, very thorny, very cold hardy if that helps.

3 Likes

Hi Bernie,

I’m in zone 3b so not as cold as you, but this info is very interesting as I’d like to grow some pears in the next few years. I remember reading some old posts by you on a different forum about apple hardiness and I’m trying what I remember to be your method this year, where I’ve grown out an apple rootstock for a couple years and then will graft the scions on branches 6" out from the trunk, in order for better hardiness. At least that’s my memory of what you did – correct me if I’m wrong. If you want to put any updates on this forum of your latest thoughts on extending apple scion hardiness, I’d love to see it! Thanks for these experiments – it’s hard to find info on growing in really cold climates!

1 Like

Callery are not dwarfing but in time will adapt to colder climates. People may not agree but they have not seen what they are capable of yet.

Hi Bernie & @nickh

I’ve been grafting for a while and know the craft as well as a lot of the “bits and pieces” that go along w/it.

There is none transfer of hardiness from one type of wood to another. No ‘antifreeze’ transfer.

It should be understood so people do not think cold hardiness of one to ‘another’ could ever be possible.

I just don’t want to advance the idea that this is possible. The scion has its’ own limitations and so does the rootstock. That’s all I want to say. And, I wish you guys hope/success!

Dax

4 Likes

As @Barkslip and @nickh allude to, I imagine that you have attempted to grow out the fumigated pear rootstock as Nick says you have done previously with apples? Giving them additional protection for year one might be necessary to give them enough time to grow out and be healthy for the remainder of their life. As I’m sure you know, younger trees can have more trouble with the cold than established ones. As Dax implies and you have obviously learned through experience, knowing your rootstock is in good shape should be priority one for cold hardiness, then it should be a matter of grafting varieties to test THEIR hardiness, which may in the end be the true issue? Please correct me if I misunderstood.

2 Likes