Thought to be native to China, the Nagami kumquat is a slow-growing tree reaching a height of 15 feet. The fruit of the Nagami kumquat is small and oval, about 1 3/4 by 1 3/16 inches. The peel is golden yellow and smooth. Both the fruit and the peel are edible--the peel is actually the sweetest part of the fruit. This citrus tree is one of the heaviest producers of kumquats and is the most popular kumquat cultivar in the United States. Kumquats require heat to bear fruit and thrive from zone 8 to 11. These trees are somewhat frost resistant.
Plant your Nagami kumquat tree in well-drained soil where it will receive full sun. Nagami kumquat can be planted in a container or in your garden
Water your Nagami kumquat frequently during the first year to establish good root formation. In later years, water when the top three inches of soil are dry.
Feed your kumquat tree with a general-purpose fertiliser in the spring before new growth emerges. For newly-planted trees, wait a month after planting before fertilising.
Spread a thick layer of mulch around the base of your kumquat in the summer to help the soil retain water. Spread the mulch in a ring starting about 12 inches away from the trunk.
Prune in the winter when the Nagami kumquat tree is dormant. Kumquat trees need very little pruning. Prune to shape or to eliminate dead or damaged branches. Any branches growing toward the centre of the tree can be cut to improve circulation. Branches growing straight up from the ground or a branch are suckers and should be removed because they drain the tree's energy.
Pick the fruit when ripe from October to January. Gently squeeze to determine ripeness--ripe fruit should give a little. Cut the fruit from the tree to prevent broken branches.
Check often for pests and diseases. Kumquat is susceptible to mealy bug infestations. Mealy bugs, like aphids, suck the sap out of leaves and excrete honey dew on which sooty mould can grow. You will notice an increased leaf drop and disfigured leaves. Ladybirds prey on mealy bugs and may be introduced to the plant if you suspect mealy bugs. If a chemical solution is required, use an insecticidal soap on the tops and bottoms of the leaves.
Use very sharp clippers when pruning your tree and cut close to the stem or trunk that the branch you are removing is attached to. Cut as close as possible without cutting into the branch collar, the swelling at the base of the branch. When removing branches larger than 1 inch in diameter, paint pruning wounds with a latex pruning compound to avoid disease. For these large branches, the recommended method of pruning is to use a saw and to start by making a small wedge-shaped cut on the underside of the branch several inches from the branch collar. Then make a second cut another inch further out--for this cut, start at the top of the branch and cut all the way through. This will leave a stub. Finally, cut off the stub as close to the branch collar as possible without damaging the collar. Kumquats growing in containers are more sensitive to the cold. Wrap the container in a blanket during a mild freeze. Kumquats can be brought indoors if you're expecting severe cold weather or a prolonged freeze.
Nagami kumquat has thorns; wear gloves and be careful when handling it.