Apple tree and orange/lemon tree thin stemmed

[Arminius]

Dear fellow gardeners,

An issue I have been batteling for years now is the my young fruit-trees are rather thin stemmed. Somtimes so thin-stemmed that they have a hard time staying straight up. I heard that the issue is usually with too much fertilizer and not enough light. However, they are quite well exposed to sun and I have given them no fertilizer. Any tips? Thanks!

[GardeningCook]

When you say "well exposed to sun", exactly what does that mean? Fruit trees need full sun like, all day. If you're having problems with spindly growth, I suspect your trees aren't getting all-day full sun.

[NesOne]

Have you pruned it? The way I understand it, is that pruning helps to promote root growth, thus thickening the main stem.

[JONA]

Hi Arminians
Your fruit trees....do you know what root stock they are on?
If the stock is of a dwarfing type.....say 9 or similar....then they will always be thin trunked. Such stocks require staking for all their lives as once in crop they are very succeptable to falling over even in slight winds. They have such a small root system and therefore little strength.

What they do though is to produce a tree that is a good regular cropper of quality fruit and to stay small in stature.
If your trees are not grafted but on their own roots, then it may be that this is their natural growth rate as such trees are always variable in how big or small they will finish.

[Arminius]

First of all, thanks of all for your responses and tips and sorry for my delayed responses!

A little bit of history about these trees. They started spontanously growing when after I spitted out the seed into a pot with some soil. I separated all the seedlings.
The apple trees were "Granny Smith", for the lemons (identified through the leaves, they could have been grapefruit or oranges as well). No idea of the root stock.

As discussed in another topic, I'm fighting powdery mildew on my apple trees they cought whilst they were in their pots inside.

They are now out on my small balcony they get I guess a full day of sun. The lemon trees are inside as I don't have enough space on the balcony and I'm afraid they might die in winter. However they are close to a windows so I hope they get enough sun.

I pruned one apple tree early but he was never thin stemmed. I am afraid of pruning my apple trees as they are infected with powdery mildew an infect the tree deeper. Is there the risk.

How far can I prune my lemon tree? Down to the woody part or should I leave some of the green stem on? Thanks for your help!!!!

[rainbowgardener]

"They are now out on my small balcony they get I guess a full day of sun. The lemon trees are inside as I don't have enough space on the balcony and I'm afraid they might die in winter"

They can't possibly get a full day of sun on a balcony, since there is a building behind it. Depending on what direction the balcony faces, it may be possibly ok to not workable. South facing (in the northern hemisphere) is best and gets a pretty good day of sun (though all from one direction), east or west would be next, and a north facing balcony is worthless for growing anything but shade plants.

Depending on where you are located, your lemon tree may well need to be inside for the winter. That does not mean it should stay inside through the growing season. It needs to come out and get more sun and air.

[JONA]

If you are growing your apples from a pip then the trunk size may be just natural. Apple trees grown on their own roots can be all over the place as regards their size and growth rates. That's why orchards are planted with grafted trees to ensure even growth.
As you planted from a pip the resulting trees are for you to name. They will not be Granny Smiths. Only one parent is known...no telling where the insect that pollinated the blossom came from with the other pollen.
You will have to deal with that mildew...it can seriously affect the trees growth and fruiting if it gets a good hold.