Are these trees grafted to the same root type of stock. Soil difference can cause growth difference.

Steve

Thanks for the question, Steve! I think the answer is yes? (underlining the “novice” in my original post) Both trees were purchased from the same nursery when they were each about 20” tall, so prior to that I unfortunately can’t speak to their grafting. The soil they’re planted in now should by all measure be identical though.

Some times it take a long time for a particular tree to grow. Are there insects like spider mites on the small tree.

Steve

That super vigorous shoot could be rootstock. Need a closer pic of it. If it has trifoliate leaves, cut it off to the trunk.

It could indeed be the sun exposure. Depending on your climate, excessive sun exposure, especially combined with very hot high temperatures, can create drought stress. That means the tree is losing water through the leaves faster than roots can pull it up.

Many people may not realize this but in desert climates, many plants grow better with a little bit of shade.

Believe it or not, the tree with more sun is likely to grow faster, in the future, once both trees have reached a very big size.

Both trees look under fed and under watered. Your surrounding landscape tells me you are in a Mediterranean climate, maybe vista, CA or northern LA County/ Ventura Which means it is fairly mild temps with the occasional heat wave. During this time of year your trees should be getting watered at least 3-4 times per week and probably daily when they’re first planted to keep the rootballs moist and help establish growth. Without proper watering and nourishment your trees will not grow very much, the sun and reduced exposure will also have an effect on the trees. One thing I did notice is that you have several suckers sprouting below the graft line which I point out in your photo that I edited for easy identification. Any branches below that graft line will need to be cut back at the trunk. I suggest going to the nursery that you purchased the trees from and ask them what “Citrus type” of fertilizer is good to use for your growing region. If you would like some more help with identifying exactly where the graft line is, take a close up photo of the trunks and post it so we can show you where it is. Your photo with arrows pointing to the graft line Is below.

Evan

Yes, what Steve said, then feed and water heavily.