Kumquat tree has dark green veins but the rest is pale green to yellow.
The tree may be suffering from an iron deficiency. This commonly causes this kind of coloration on the leaves. This normally happens either when the plant is watered too much and the nutrients get leeched away or if the pH is too high. Test the soil and correct and nutrient and pH issues found when testing. Also, make sure that the soil is not too porous, which may let the water run away too quickly.
I've noticed that the tiny green fruit on my potted kumquat trees have fallen off. Also, one green fruit was the size of a round grape and it is missing from my tree. Can you explain what's happening and what can I do to help my fruit reach maturity?
It is either a watering or nutrient issue. Increase watering to the plant and use a slow release fertilizer so that it gets even feeding.
What numbers on fertilizer bags are best for kumquats and orange trees growing in Sebring, Florida (sandy soil)?
Try using a complete fertilizer with N-P-K ratio of 5-1-3 (5 parts Nitrogen-1 part Phosphorous-3 parts Potassium) every six to eight weeks. Citrus plants are heavy nitrogen feeders. A slow release granular fertilizer works best.
The trees have produced flowers and fruit in the past and were pruned last year. Since then, no flowers or fruit. They are in the ground and about three to seven years old. They have been given three waterings of commercial fertilizer for citrus fruit since late winter.
I would recommend adding phosphorus to the soil. This is likely the cause for not flowering, which means no fruit. This article will explain more: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
I fertilize 3 times a year, water deeply once a week and they don't seem to have any disease, just never a single flower in 8 years.
I would have the soil tested. It sounds as if there may be a nutrient imbalance--too much nitrogen/too little phosphorus. In order for plants to bloom or fruit, they need phosphorus. Bone meal is a great way to add this nutrient to the soil. Here is more information: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
How to take care of an Asian kumquat tree.
This article should help: https://www.gardeningknowhow.com/edible/fruits/kumquat/growing-kumquat-trees.htm
I have a kumquat tree. It has grown quite large in the 3 years I've had it. It bears an enormous amount of fruit and seems to be everbearing (at least it always seems to be bearing some all year). When I planted it too close to the house, I wasn't expecting it to grow so large, so now I need to move it. What I would like to know is the proper way to prune it to keep it at a height I can reach. Also, can I move it without killing it? Right now it is about 8 feet high and wide. What kind of root system would it have?
The following link leads to a very informative article that includes pruning information: https://www.gardeningknowhow.com/edible/fruits/kumquat/growing-kumquat-trees.htm