With the ability to fruit for approximately 50 years, orange trees (Citrus spp.) do not have a dormant period, but remain evergreen and active almost all year. Thriving in U.S. Department of Agriculture plant hardiness zones 9 through 11, orange fruits take considerable time to ripen on the tree. In fact, it is normal to see both flowers and ripe fruit on the tree at the same time.
Orange trees take advantage of winter's slow growth period to start flower bud growth into the springtime. Depending on the orange variety, there may be more flowering flushes into the summer and fall as fruits ripen alongside them. With intoxicating scents, blossoms invite pollinators, such as bees, to visit the trees for nectar feeding. Although orange trees can self-pollinate, fruit set and quality are widely improved with insect cross-pollination. However, large flower clusters do not automatically become huge fruit groupings -- many blossoms fall to the ground in response to environmental conditions, from extreme temperature swings to water availability.
Because of intricate fruit development, orange trees take between five and 18 months to generate edible fruits. Each variety has its own set development time; larger fruit sizes typically take longer to grow. Orange trees cannot wait out this time period without blossoming activity, so they are commonly filled with both white flowers and small, orange fruits. Several yearly flowering flushes occur, making fruit harvesting time almost a constant activity with various pollination times stretching throughout the year.
Harvesting With Nearby Blossoms
Pulling fruit from a blossoming orange tree is bound to knock some flowers to the ground. However, harvesting activity does not significantly reduce future fruiting. Thousands of blossoms grow on the tree each year for potential fruit development. If you want to maintain as many flowers as possible on the tree, you can allow the fruits to remain on the tree for up to four months after initial ripening. Once your current blossoming time is spent, you can harvest the ripened fruits without extensive flower loss. In fact, these fruits will slowly lose their acidity and gain more sweetness as they ripen longer on the limbs.
Along with displaying fruits and flowers at the same time, orange trees also perform a drop to avoid overweight limbs. Typically between May and July, small fruits fall from the tree before they fully develop. This self-defense mechanism might also knock blossoms off as well, but it preserves the tree's stability. If all the pollinated flowers produced ripened fruits, the limbs could easily break and cause widespread damage where pathogens might enter the tree. Too many ripening fruits also creates tiny oranges because trees can only apply a small energy amount to each fruit. Dropping both blossoms and small fruits allows the tree to produce high quality oranges for many years to come.