This is kumquat A. I purchased him this year at Baker Nursery. He's planted in the ground, has direct sun up until 1 pm (and then shade), has good drainage and is watered deeply once a week. This is the second time he's flowering; all of the first fruit dropped off and many of these flower buds drop when touched. I don't think he's had any new growth, and some of the leaves are starting to dry up and the ends of the branches are dying -- you can see the brown branches.
This is kumquat B. I purchased him a week after kumquat A and never got around to planting him in the ground -- he's still in the pot from Baker. He lives in my family room, gets indirect light and air conditioning. I take him outside for several hours each weekend so he can get direct light and fresh air. He didn't have many flower buds, but he now has six lovely kumquats on him. The leaves are much greener than kumquat A, and he has new growth. I only water him every few weeks (the water meter says the soil is moist).
So why is kumquat B doing so much better than kumquat A? I thought they needed heat to do well. And what causes the ends of the branches to die off? Should I be fertilizing them? I confess I gave kumquat A some Miracle Grow last week in the hopes that it would help him, but I haven't noticed a change.
The die back can be caused from too much water (fungus). Maybe it could also be a little transplant shock. Usually it's recommended to hold off fertilizing for the first year, and be sure the one in the ground is not buried too deep and the root flare is exposed to avoid future complications. :)
Miracle grow won't help him much in Arizona alkaline and nutrient poor soil. I would try ironite. And maybe pour gypsum to work into soil and cover the top of the ground with a thick layer of mulch. He looks hungry for nutrients and dry...that is a lot of sun and citrus can be vulnerable to sunburn. I think a cup of ironite would help him to do well in tough conditions.
Ironite only covers up the improper pH of the soil. The gypsum is good, as it helps to lower the pH of the soil.
Who told you Miracle grow won't help in Arizona?
I wouldn't apply anymore fertilizer. Twig die back is also a symptom of root damage- perhaps when you planted? I would let the tree be and water appropriately. The tree isn't showing sign of chlorosis, so I don't see a need for ironite. I do see a little leaf curl, that could be caused by a number of factors. It doesn't look like thrip- could be spider mites, but most likely the watering schedule.
How did you plant the tree? (Amendments, backfill, depressed, etc.?)
How deep is it planted?
What's the drainage like?
When are you watering, how and for how long?
I planted in the native soil, with a cup of gypsum and a gallon-sized pot of Bio-flora compost mixed in. It's not planted deep -- I planted it so that the root crown was even with the surrounding ground. The drainage is good -- the basin drains within 5-10 minutes when filled. I have my trees on a separate drip system, so I use that to water once a week, and I run it for 6-8 hours, so they get a good, deep soak.
I've put some organic mulch that I purchased at Root on top of the soil, but it seems more like compost than mulch to me, so I'd like to get a better mulch for it. But I don't know what to buy. I'm tempted to get the coconut fiber substrate that I use for my toad's terrarium -- it looks like it would be a good mulch.
Most of the so called compost/mulch I have seen here in Arizona is not very good quality. You have a modest amount of nitrogen bind happening is all. It will go away with some nitrogen added and time.
When/if you plant the other tree in the ground, do not add any ammendments like compost or mulch to the soil when you plant, just plant in the native soil. You will have much better results and faster growth overall, especially the second year. :)
The coconut fiber is stated to be a good mulch, although I have no personal experience with it.
Part of the problem is Bakers repots their plants. Leaving the B plant in the pot keeps it from suffering transplant shock, which for citrus last about 3 years. Yes, you can figure a transplanted citrus will need 3 years average to recover from being transplanted.
So by leaving B in the pot, you have reduced this problem, also kumquats can be more sensitive than some other citrus to heat, transplant, soil conditions, etc...
Overall Plant A looks fine, and look to it doing well in one or two more years, likely passing up plant B in about 2-3 years.
Thanks for all of the comments. I hadn't considered transplant shock. It's been two months since I planted A, so I suppose there could be lingering damage.