There are three varieties of kumquats (also known as ‘cumquats’), the Nagami and the Marumi (also known as the Calamondin) and Meiwa.
Nagami: the ‘Nagami’ kumquat is the best one for eating straight off the bush, as it is the sweetest. It is the most commonly grown kumquat and produces a high volume of small, bright orange oval fruit. It makes an excellent container or pot plant. A kumquat tree planted in a container or pot will grow to a height of around four feet, but outdoor trees can grow to 13 feet or more.
Marumi (Calamondin): Marumi trees fruit several times a year, with the main crop in winter. The bushes are dense and they are the best looking of all citrus in containers. A beautiful variety with variegated leaves also is available.
Meiwa: Meiwa kumquat trees are more cold resistant than other varietals with larger, sweeter fruit—about the size of a small tomato. They are grown in China and Japan, but are rarely seen elsewhere.
For more information on these kumquat tree varieties refer to our Varieties of Kumquat Trees blog.
Both the Nagami and Marumi kumquat trees are popular and grown widely in Australia.
Both the Nagami and Marumi kumquat trees are cold-hardy and grown in Florida where they are harvested November to April.
Both Meiwa and Nagami kumquats are cold-hardy. Tree foliage can withstand temperatures below 20º F and therefore can be grown in areas that are too cold for most citrus. Fruit, however, are more cold sensitive.
Nagami is the most common variety found in grocery stores. Nordman Seedless Nagami, a new release, has really nice fruit 1 to 1½ inches long without seeds, therefore, especially easy to eat or preserve.
Both Nagami and Meiwa kumquats have very good cold hardiness and are suitable for growing in Texas.
You will find full details about kumquat trees and other citrus trees and great advice and photos on recognising and correcting nutrient deficiencies, pest and diseases and problems in Grow Citrus: The Insiders Secrets to Growing Great Citrus