About Growing Citrus Trees in Zone 7
Temperatures in USDA zone 7 may dip down as low as 10 to 0 degrees F. (-12 to -18 C.). Citrus doesn’t tolerate such temperatures, even the hardiest citrus tree varieties. That said, there are a number of things you can do to protect citrus trees grown in zone 7. First off, never plant citrus in an area where it will be assaulted by cold northern winds. It’s important to select a planting site that not only gets plenty of sun and has excellent drainage but one that will provide some cold protection. Trees planted on the south or east side of a home will get maximum protection from winds as well as radiated heat from the house. Ponds and other bodies of water or overhanging trees will also help trap heat. Young trees are most susceptible to cold temps, so it might be advisable for the first few years to grow the tree in a container. Be sure that the container drains well since citrus doesn’t like wet “feet” and put it on wheels so the tree can be easily moved to a more sheltered area. A good layer of mulch around the base of the tree will help to keep the roots from getting any freezing damage. Trees can also be wrapped when chilly temperatures are looming to give them even more protection. Cover the tree completely with two layers – first, wrap the tree with a blanket and then plastic. Unwrap the tree the next day as temps warm and pull mulch away from the base of the tree to allow it to absorb heat. Once the citrus tree is 2-3 years old, it can tolerate lower temperatures better and recover from freezes with little to no damage, much more easily than young trees can.
Cold Hardy Citrus Trees
There are both sweet and acid types of citrus trees suited for zone 7 provided there is adequate protection from cold temperatures. Selecting the proper rootstock is crucial. Look for trifoliate orange (Poncirus trifoliata) rootstock. Trifoliate orange is the superior choice for cold hardiness but sour orange, Cleopatra mandarin, and orange crosses may be used. Mandarin oranges include mandarins, satsumas, tangerines, and tangerine hybrids. They are all sweet types of citrus that peel easily. Unlike other zone 7 sweet citrus trees, mandarins need to be cross-pollinated for the fruit to set.
Satsumas are one of the most cold-hardy of the citrus and differ from mandarin in that it is self-fruitful. Owari is a popular cultivar, as is Silverhill. They fruit well ahead of any potential freezes (normally fall season) and have a relatively long shelf life of about two weeks. Tangerines are the next best bet with regards to cold hardiness. Dancy and Ponkan tangerines are self-fruitful but another cultivar, Clementine, requires cross-pollination from another tangerine or tangerine hybrid. Tangerine hybrids such as Orlando, Lee, Robinson, Osceola, Nova, and Page are preferable over Ponkan or Dancy, which ripen later in the season and are susceptible to colder temps.
Sweet oranges should only be attempted along the lower coastal areas of zone 7 combined with adequate cold protection. Hamlin is a great choice for those that wish to grow oranges for juice. It has the greatest cold hardiness of the sweet oranges, although it will be damaged at temps down to 20 degrees F. (-7 C.) or lower. Ambersweet is another sweet orange variety to try. Navel oranges can also be grown with adequate protection from cold. Although they are not as fruitful as sweet oranges, they ripen fairly early from late fall through early winter. Washington, Dream, and Summerfield are types of navel oranges that can be grown in the more temperate coastal regions of zone 7. If grapefruit is your favorite citrus, realize that it lacks much cold hardiness and it can take 10 years or more for a seedling to produce fruit. If that information doesn’t deter you, try growing Marsh for white seedless grapefruits or Redblush, Star Ruby, or Ruby for red seedless. Royal and Triumph are delicious, white seed varieties. Tangelos might be a better bet for grapefruit lovers. These hybrids of tangerine and grapefruit are more cold hardy and have fruit that ripens early. Orlando is a recommended cultivar. Also, Citrumelo, a hybrid between trifoliate orange and grapefruit, grows rapidly and produces fruit that tastes like grapefruit, and may be grown in zone 7 with adequate protection. Kumquats are the most cold-hardy of acidic citrus. They can tolerate temperatures down to 15-17 F. (-9 to -8 C.). The three most commonly propagated are Nagami, Marumi, and Meiwa. Calamondins are small, round fruits that look similar to a tangerine but with a very acidic pulp. The fruit is sometimes used as a substitute for lime and lemons. They are cold hardy down to the low 20’s. The Meyer lemon is the most cold-hardy of the lemons, producing large, almost seedless fruit that ripens over the course of several months, beginning in late summer. It is cold tolerant down to the mid-20’s. Limes are not particularly cold hardy, but the Eustis limequat, a lime-kumquat hybrid, is hardy into the low 20’s. Limequats make great lime substitutes. Two cultivars to try are Lakeland and Tavares. If you want to grow citrus for its visual appeal more than its fruit, try growing the above-mentioned trifoliate orange (Poncirus) that is most often used as rootstock. This citrus is hardy in USDA zone 7, which is why it is used as rootstock. The fruit, however, is hard as a rock and bitter. Lastly, a popular citrus that is extremely cold hardy is the Yuzu. This fruit is popular in Asian cuisine, but the fruit is not actually eaten. Instead, the flavorful rind is used to enhance the flavor of many dishes.
