Kumquats are small citrus fruits, eaten whole, peel and all. The flavor is a combination of sweet and tart citrus. They are also used in marmalades and preserves. Kumquats are subtropical trees, grown mainly in Florida, California and Texas. They grow well in containers in other locations. Originally native to China, they have been grown in the U.S. since the mid-1800s. Kumquats are among the most hardy citrus trees, able to withstand freezing temperatures to 18 degrees F, once established.
Purchase grafted plants from a nursery and plant kumquats in a sunny location. Grafted plants are grown on superior root stock and do much better than trees grown from seed.
Remove the tree from the pot and rinse off the outer layer of soil. Unravel the outer layer of roots, so that they are sticking out from the root ball. Place the roots in a bucket of water to soak while you dig the hole.
Dig a hole large enough for the root ball and spread out roots. Place the plant in the hole about 1 inch higher than it grew in the pot, making sure that the grafting union is above ground level. Fill the hole halfway with soil, and water to settle the soil. Fill the hole completely, and tamp down to firm the soil and secure the tree.
Form a watering ring around the outside of the hole by mounding extra soil in a continuous ring 5 or 6 inches high. Water the newly planted tree immediately after planting. Continue watering once or twice a week, by filling the ring with water. Gradually increase the time between watering until the tree is established, then water only during drought conditions.
Apply a 3- to 4-inch layer of organic mulch around the outside of the tree. Keep the mulch about 1 foot away from the trunk to discourage rotting and disease.
Wait a month after planting before fertilizing. Water before fertilizing, then apply a citrus formula that contains slow-release nitrogen. Water again after fertilizer application.
Harvest kumquats by clipping the stem above the fruit with pruning shears. Many gardeners include a few leaves with the fruit to enhance its beauty in the bowl.
Prune the kumquat tree after harvesting the fruits. Shape the tree and remove dead or diseased limbs. Remove suckers growing up from the roots or from the lower portion of the trunk.