Just Say No to Dwarfing Rootstocks

Tall Spindle Apples

The day has come when I’ve given up on more dwarfing apple rootstocks like M9, Bud. 9, and P22. This is partly because I have found that semi-dwarf like M7 and M111 will do everything I need to do.

I’ve found that a warm climate itself has a dwarfing effect on apples, especially high-chill varieties (which we grow just fine in a low-chill climate). The photo above shows four-year-old semi-dwarf M7 trees trained as a tall spindle, bearing heavily; the varieties in front are Rome Beauty, Gala, and Terry Winter. They require almost no pruning, summer or winter, other than housekeeping like crossed or broken branches. I can easily reach the top branches on these and also the free-standing M7 trees I space 5′ apart from each other. I’m going to try training some M7 as Belgian Fence espalier this spring to see how it adapts to a 6′ high trellis, but I imagine it will be no problem.

On the other hand, more dwarfing rootstocks like M9, Bud. 9, P22, and M27 have proven just too wussy for our hot climate. They grow like a rocket the first year (probably because they were refrigerated and received sufficient chill) but just peter off after that, and cannot recover from any damage such as borers or broken limbs. They must be permantly staked against our Santa Ana winds, and heaven help it if the irrigation putts out during one of our frequent heat waves!

In the tropics apples are commonly planted on seedling rootstocks spaced 6′ apart in rows 9′ apart, and they easily are kept short enough to harvest without ladders. The only exceptions to the above I’ve found is with very low-chill varieties like Anna and Dorsett Golden, which grow like rockets and will get very big if not spanked severly in the summer with corrective pruning. This reinforces my theory that the warm climate is what stunts the tree’s growth, as in colder climates M7 easily reaches 15′ tall, something mine never seem destined to do.

By the way, precociousness (fruiting early in the tree’s lifetime) has not been an issue, with both M7 and M111 often fruiting the second year- perhaps the stress of a hot climate has something to do with this. This takes away one of the final arguments for using a very dwarfing rootstock.


One Response

  1. I have found many of the same complaints trying to grow apples here in the southeast. The Bud9 rootstock are just too heat sensitive, and even though we get enough chill hours here, the heat and humidity stifle vigor and I have moved to Bud 118 and am having very good success.

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