Seeds & growth
Rootstock
The root system a fruit tree is grafted onto, which controls its eventual size and vigour — letting you grow full-size apples on a small, garden-friendly tree.
When you buy a fruit tree, you're really buying two plants joined together. The rootstock is the root system and lower stem; the scion is the variety you actually want to eat — a Bramley apple, say, or a Victoria plum. The two are joined by grafting, where a bud or shoot of the chosen variety is fused onto the roots of another. You can usually spot the join as a slight kink or bulge low on the trunk, just above the soil.
This matters because the rootstock, not the variety, decides how big and vigorous your tree becomes. The same Bramley apple can grow as a tidy patio tree or a towering orchard giant depending entirely on what it's grafted onto. That's brilliant news for UK gardens, where space is often tight.
Apple rootstocks, by size
Apple rootstocks are the easiest to understand because they're so clearly graded:
- M27 — very dwarfing. Grows to roughly 1.5–2m. Ideal for large pots and tiny gardens, but needs permanent staking and good feeding.
- M9 — dwarfing. Around 2–2.5m. A popular choice for small gardens; also needs staking.
- M26 — dwarfing. About 2.5–3m. A little more robust and forgiving for beginners.
- MM106 — semi-vigorous. Reaches 3–4m. Good for a free-standing tree where you have the room, or for training against a fence.
Plums, pears and cherries have their own rootstocks (such as Pixy and Gisela for plums and cherries, Quince C and Quince A for pears), all working on the same principle: smaller rootstock, smaller tree.
Choosing by your space
Start with the space you have, then work backwards to the rootstock. For a balcony or patio pot, look for M27 or M9. For a small garden bed, M26 is a sensible middle ground. Only choose MM106 if you genuinely have room for a 3–4m tree and a ladder to pick it.
Rootstock also shapes how you can train a tree. A dwarfing rootstock keeps growth restrained enough to grow a cordon — a single-stemmed tree grown at an angle against wires or a fence, letting you fit several varieties into a narrow strip.
One last thing worth knowing: most fruit trees need a compatible partner nearby for good pollination and a decent crop. The rootstock sets the size; the variety and its pollination group set whether you get fruit at all. Check both before you buy, and you'll end up with a tree that fits your garden and actually fills your fruit bowl.
In a UK garden
Most fruit trees sold at UK garden centres and nurseries are labelled with their rootstock (like M27 or MM106), so checking that label is how you avoid buying a tree that outgrows a small British garden.
Example
An apple on M27 rootstock stays around 1.5–2m and crops happily in a large patio pot, while the same variety on MM106 becomes a 3–4m tree needing real space.