Patio fruit trees - To Re-pot or not to re-pot??

[andyblr]

Hello,
I've just bought 2 patio fruit trees (a pear and a peach about 3 foot high each). They are both in 7.5 litre pots. The care instructions say to grow in 30 litre pots.

Would people recommend re-potting as soon as possible? and, if so, should I go all the way to 30 Litre in one go or move up in smaller jumps. I'm new to container growing so am a bit clueless, but I have heard that it is better to move up only a few litres at a time as otherwise the plant puts too much energy into growing roots and not enough into the rest of the plant. Is there any truth in this?

Any help greatly appreciated, - Andy

[rustylady]

The advice about moving up pot sizes gradually applies more to things like houseplants and veg like tomatoes, courgettes etc. The reason isn't about the plant using energy to grow roots - it's more so the roots don't rot in a vast quantity of cold wet compost.

Fruit trees are a bit different though, and I would think straight into a 30 litre pot should be fine. Make sure you use a compost like John Innes with some weight in it. Multi-purpose would be far too light and fluffy.

[FB.]

The reason isn't about the plant using energy to grow roots - it's more so the roots don't rot in a vast quantity of cold wet compost.

It's also because a pot restricts the roots, which is in itself dwarfing. When a root reaches a physical barrier (the edge of a pot, a rocky subsoil etc) the root sends out a signal to the leaves to slow down growth - this acting to ensure that the shoots don't get carried away growing rampantly when the roots can no longer continue spreading out to find nutrients and water.

So by stepping-up one size at a time the plant is kept as dwarf as possible for as long as possible. If repotted into a big pot, it will put on a growth spurt until it has filled the pot.

My preference is to use an equal mixture of compost and garden soil - the garden soil adds weight and stability to the pot and is easier to rehydrate than compost (water seems to run straight through dry compost). The compost:garden soil mix is also less fertile which reduces the amount of excess leafy growth which will otherwise divert energy away from fruiting.

However, potted plants - especially dwarf varieties which need good soil to give their best - will need changes of compost every few years because of the inability of the roots to search outside of the pot for nutrients once the soil in the pot is exhausted.
I would expect triploid varieties (when on dwarf rootstocks; triploids are often vigorous growers) to cope well in pots where neglect may be a problem, since the triploids are less nutrient-demanding and more resilient than the diploids.

[rita1]

hi i put all mine straight into a 30L tub, i added a few more holes, they all seem to be doing ok.