If you’re looking to plant an orchard or even a single tree for your garden, after thinking about what variety you might like to grow, the biggest consideration will be which rootstock on which to grow it and the interplay between these two things will also have a bearing. For commercial Bramley growing, M26 is a near perfect rootstock, as the dwarfing habit of M26 limits the extreme vigour of Bramley as a variety. You will need to understand renewal pruning to realise a decent crop year on year though. If, however, you’re thinking about Court Pendu Plat as your garden variety, M26 would be a terrible choice as the variety is so low in vigour, you’d likely not see much in the way of fruit at all and MM111 would be much better, it will still only likely grow to a few metres tall. Thus are the seeds of confusion sown. What it really comes down to is: How big do you want your trees to be, how soon do you want fruit and how hard are you prepared to work to get it?
If you want an orchard of mighty standards, seedling stocks or M25 standard size stocks are for you. My caveat to this is that, in my experience, if M25 are planted in good, base-rich soil, the root system will not have to work hard enough in youth to make sufficient scaffold support to hold firm the standard size tree at maturity and they are prone to tipping over when fully grown. If you have lovely rich soil, I’d opt for MM111. It will make a nice big tree and hold firm in the ground. If, however, you’re after trellis growers for the garden wall, M26 is probably a good choice for you. There is a trade off here. If you want small trees to produce high yields, the thing which makes them small is a paucity of root structure, so the fragile darling will require a sturdy support for the entirety of its dramatically reduced lifespan and careful fertilising and weeding to maintain this idyllic position. Dwarfing trees require a significant investment of time and care to thrive. Massive trees live a long time and require next to no input once they are established, but acre for acre produce a lower yield.
Apple trees do not grow true from seed – this another whole thing for a separate excursion – but that is the reason for needing rootstocks at all. You can’t take the seed from your tasty discovery apple and expect to grow it into a tree which produces identical fruit. Doesn’t happen. It might grow something similar, wildly different or even better, but not identical. Apple varieties require clonal propagation if repetition is required. Commercial orcharding is an exercise in monoculture production in exactly the same way wheat is grown: it all needs to be the same and ready at the same time. The rootstocks with grafted varieties ensure this. As above, so below in this instance. It makes top fruit production predictable as far as possible. The majority of commercially available rootstocks have resulted from breeding programmes at significant institutions such as the East Malling Research Station, or the Geneva series from Cornell University and represent a significant investment of time and labour to bring to market. Those which succeed combine various favourable traits of growing form and pathogen resistance.
For the sake of brevity and the working usefulness of this information, stocks which have been discontinued or no longer in widespread use have been omitted. When I started delving into this a bit deeper, and I began to look at the Geneva series, the Budogovsky series, the Ottowa series, the Poland series, the JM series and so it goes on, thinking it would be good to make an international comparison, I realised that if I’m imparting any information about any of these other than the M and MM series stocks from the UK, all I’m doing is regurgitating half-baked research as I’ve no direct experience with them at all (except P60 from the Poland series, which I have found to be a good alternative to M9 and produces an interesting red-flesh apple). I also quickly realised that this sort of comparison is of very little save academic use
However, given the range available, I’ll list some of the stocks in the various series available for your consideration:
Geneva series (G or CG): G11, G41, G16, G213, G214, G814, G257, G935, G66, G222, G202, G484, G969, G30, G210, G890; Budogovsky series (USSR origin, but quite widely available in US) B9, B118; Ottowa series O3 widely available; Poland series P2, P16, P18, P22, JM series (Japan) JM1, JM5, JM7, JM8 and so it goes on and on and on. Actually for the best resource on the sheer range of material available and information on some of the trials taking place around the world, the website www.rootstocks.info is a brilliant resource aligned to the book compiled by Lowell Cordas.
Comparative chart M/MM series
There are a load more in the M series, but these are basically the stocks which are widely available now and nearly all commercial orchards and trees available for sale from nurseries will be on one of these stocks.
The simple fact is this: there is (or was) a research institute not a million miles away from the place you intend to plant apple trees which will have developed a range of rootstocks to suit the growing conditions in your area. There will likely be something available to suit your plans. The fall back position is that you go out in your local area and look around for seedling trees growing in hedges and woodland edges, wasteland and roadsides. If one of those trees looks like the sort of thing you are after, making allowances for the maturity of what you have found – check it is disease free – harvest some of the fruit come autumn and grow the seed on to make your own rootstocks. Most of the apple trees I have as grafts started out as seed-grown whips. It’s a lovely way to short-circuit the below-ground genetic monotony of clonally produced trees. Obviously if you need to produce a 600 tonne crop of Gala, your workforce is on site for three weeks each harvest, the rains are coming and it’s all got to be in store ASAP, seedling stocks are definitely not for you, but if you’re planning a mixed variety, traditional orchard whereby the trees will ripen their fruit at different times anyway, introduce some below-ground diversity with seedling stocks. The world will be the better for it. You could even let some of those seedlings grow on and see if their fruit is useful to you – you can always top work them over to other things later if it’s no good to you…
More on that another time.
Thanks James, this is easily the most graspable explanation of rootstocks I've read - and I've read lots about rootstocks!
Love the idea of using seedlings and I have actually been spreading pomace about the place since I’ve been making cider (5 years) and have maybe 5 seedlings to show for it! Initially I was thinking about getting novel & unique varieties inspired by Andy Brennan’s book but its good to have the backup of being able to top work them over to something more desirable. I hadn’t really thought about that possibility. And good to be reminded of the importance of diversity below ground as well as above.
Something I am curious about is that in all the years our old orchard has been standing ( 5 apples left, 2 pears, 90+ years old we think), I have never seen any seedlings… Admittedly I’ve only been paying attention for last 10 years maybe..
Theories are: a) 3 of the 5 remaining apples are probably triploids, therefore unlikely to yield offspring, b) rabbits, c) deer d) voles, mice, redwings etc. But now there are seedlings popping up from pomace (including seed from non-triploid apples from other orchards). Still rabbits and deer around. I guess the sheer concentration of seed in a pile of pomace allows some to escape hungry mouths and germinate.
Is it planting 101 next ?! I am just about to start planting out trees on mm111 (a few on m116) which I have grafted over the last 4 years. We are on heavy clay that can be very wet in the winter so I have staked out the parts of our field that are a little higher and less squelchy and avoiding the boggier areas. I will also attempt to mound plant where necessary. I’ve thought about reinstating ditches around perimeter of the field but at the moment thats prohibitively expensive and also quite like the idea of letting the land be boggy if that’s what it wants to be! Maybe I can just make little swale/ditches around my groups of trees to locally aid drainage if needs be (Maybe a little deluded here!)
Whoever planted the old orchard really knew what they were doing - there is a quite deep seasonal pond in the middle of the orchard which we think was actually excavated back in the day and the spoil used to bring up the soil level when the orchard was originally planted.
Looking forward to the next instalment. Cheers, Hamish