Did you placed your orange tree in full sun?
Did you planted your orange tree in a loamy soil?
Do you allow your orange fruits to remain on the tree for longer when the winter sets in?
Were you adding fertilizers before growing season?
Is your orange tree a well established one?
Oranges are native to tropical and subtropical locations and thrive in those conditions. You should ensure that the orange tree is planted on the sunny side of your property where it can get as much sun as possible.
Orange trees thrive in a loamy soil. Heavy clay soils will not allow for a strong root system and will cause sub-standard fruit production.
The acid content in oranges is reduced as the fruit remains on the tree in cooler temperatures. Allowing the fruit to remain on the tree just a little longer as winter sets in allows for a sweeter fruit. Peel color is an indicator of fruit maturity. The more deep-yellow or orange the peel is, the more mature and sweet the fruit will be.
Oranges need just the right amount of nitrogen throughout the growing season to produce sweet fruit. Fertilizers should not be added until the tree begins to grow. Also, too much fertilizer can produce leggy growth and a reduction of fruit.
Once the orange tree is established, watering should be slow and about every couple of weeks. Too much water will make the fruit less sweet.
You have done all you can to ensure you're growing sweet orange fruits.
One of the things you can do to make your oranges sweeter is to choose a sweet orange variety of tree and allow it to establish itself for a few years before expecting great tasting fruit. It is said that older trees will produce the best and sweetest fruit.
https://www.gardeningknowhow.com/edible/fruits/oranges/oranges-taste-sour.htm
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Sreten null
Hi! I’m Sreten Filipović. I graduated from the Faculty of Agriculture at the University of Belgrade, with a master's degree in Environmental Protection in Agricultural Systems. I’ve worked as a researcher at Finland's Natural Resources Institute (LUKE) on a project aimed at adapting south-western Finland to drought episodes. I founded a consulting agency in the field of environment and agriculture to help farmers who want to implement the principles of sustainability on their farms. I’m also a founding member of the nonprofit organization Ecogenesis from Belgrade whose main goal is non-formal education on the environment and ecology. In my spare time, I like to write blog posts about sustainability, the environment, animal farming, horticulture, and plant protection. I’ve also published several science-fiction short stories.
You can find me on LinkedIn at https://www.linkedin.com/in/sreten-filipovi%C4%87-515aa5158/