By Keith Hansen
Smith County Horticulturist, Emeritus
Texas A&M AgriLife Extension Service
Don’t you just love biting into a fresh, sweet, juicy orange? Especially if it is easy to peel with no seeds to spit out? How about the possibility of growing and harvesting your own citrus every fall? Well, you can with the satsuma mandarin.
Satsumas, tangerines, clementines, Halos, Cuties an other mandarins — Oh my! They are all orange in color, but what’s the real difference between them? An even more important question is, “Can I grow any of them at home?” The answer to the first question is a bit complex, but the answer to the second question is “Yes!” in most parts of Texas. At least, you can grow the sweetest of the bunch: satsumas.
A simple fact is that all of the citrus I mentioned are types of mandarin oranges. One characteristic of mandarin oranges is that they are flat on the bottom rather than round like the larger oranges. Mandarins also have thinner, easier-to-peel skin than oranges.
Of all the mandarins, satsumas are among the most cold-hardy of the sweet and relatively seedless citrus. That’s a great combination! Plus, the skin is very loose, making it incredibly easy to peel. I just hate getting orange peel under my fingernails when peeling oranges.
As mentioned above, satsumas are mandarin oranges (Citrus unshiu). They originated in China and Japan, where they are the most popular citrus variety. At the turn of the last century, millions of satsumas were planted all along the Gulf Coast. Several severe freezes ultimately limited commercial production to the southernmost areas of the Gulf States. In Texas, a severe freeze in 1911, and then a hurricane in 1915, forced commercial production to the Lower Rio Grande Valley. The Texas Experiment Station at Beeville, Texas, reported growing satsumas as early as 1909. There are reports of about 800 satsuma trees growing in the Texas Winter Garden area south of San Antonio in the mid-1940s. I suspect severe freezes reduced that number to mainly hobby trees in home gardens.
Because satsumas are the most cold-tolerant of the sweet citrus, interest in them has remained high. In 1994, horticulturists with the Texas A&M AgriLife Extension Service conducted field trials in the Uvalde area to determine the most cold-tolerant citrus to promote in the Texas Superstar program. After several years, they determined two varieties that stood up to the test of time and cold. They are ‘Miho’ and ‘Seto’. These originated from seed imported from Japan. Dr. Larry Stein and Dr. Jerry Parsons found in their field trial that these not only had exceptionally high quality but were more tolerant to freezing temperatures by several degrees compared to ‘Okitsu’ and ‘Kimbrough’, two other popular satsuma varieties.
In 2010 ‘Seto’ and ‘Miho’ satsumas were added to the Texas Superstar program as high-quality citrus for the home garden. Write-ups about them included cautions about protecting them the first few winters. For gardeners living north of the recommended range for satsumas (USDA Zone 9), it was recommended they be grown in a 20-gallon container and moved indoors when the temperature fell to 25° F or colder. I obtained both varieties in 2009 and 2010 and have been growing them in large, plastic terracotta-looking pots since I live on the borderline of USDA Zone 8b/8a. During the winter, I drag them into the garage when cold weather threatens and pull them back out into the sun when the danger of severe freeze has passed.
The Extension horticulturists with the Texas Superstar program continued to push the hardiness boundary for homegrown satsumas. In 1997 Dr. Parsons teamed up with Dr. Ying Doon Moy, a plant breeder working at the San Antonio Botanical Garden, to create a more cold-hardy, sweet and seedless satsuma. To extend the hardiness range, Dr. Moy crossed the high-quality ‘Miho’ and ‘Seto’ varieties with a more cold-hardy tangerine named ‘Changsha’. ‘Changsha’ is one of the most cold hardy of all the sweet and edible citrus, successfully grown as far north as the Dallas/Fort Worth Metroplex, tolerating low temperatures to 15° F if it was acclimated to progressively colder weather. Like other subtropical plants, a sudden low temperature, even in the mid-20s, without any previous exposure to cold would seriously damage it. A major downside to ‘Changsha’ is that it is very seedy.
After years of selections and trials — the results of the original crosses — two varieties were selected to be added to the Texas Superstar lineup. ‘Orange Frost’ was added in 2014, and ‘Arctic Frost’ was added the next year. Both bear high-quality fruit with very few seeds and have an extra bit of cold hardiness.
The key to growing any satsuma is to protect the tree for the first few years until it is very well established. This is true whether you plant them in the ground or grow them in large containers. Trees growing in the ground can be protected with a makeshift PVC frame covered with clear polyethylene. Young trees should be protected if the temperature is predicted to fall below 25° F. Once they have been growing for more than three years, they should be able to withstand temperatures down to 20° F. That depends, however, on when extreme cold occurs. Ideally the trees will experience progressively colder temperatures starting in fall before severe cold occurs later in winter.
For trees planted in the ground, it is recommended that you put a bank of soil or mulch up and around the trunk at the onset of winter weather. This is an insurance policy in the event severe cold causes dieback of the main stem. The parts protected by the mulch will have a chance to bud out and regrow into a new tree the following spring. For trees that are grafted, which ‘Miho’, ‘Seto’ and ‘Okitsu’ most likely will be, the bank of soil or mulch must extend above the graft union to protect the scion. ‘Orange Frost’ and ‘Arctic Frost’ are typically grown from cuttings; and, therefore, they are sold growing on their own roots, which is another advantage to these two cultivars. It is important to remove the bank of soil or mulch once the threat of severe cold is over in the spring.
As I mentioned earlier, I grow my two trees in large plastic containers. These large pots measure 24 inches wide by 18 inches tall and would be classified as a nursery #25 pot. Keep in mind that satsumas are trees, and eventually (and rather quickly) fill up the containers with roots. Therefore, they need to be repotted every few years. In late winter, just before spring flush, pull the plants out of the pots and trim off roots around the edges and bottom of the root ball. You might also take a jet water nozzle to remove some of the older potting medium. Replant with fresh potting soil on the bottom and sides of the pot.
If you live in the southern parts of Texas and are growing your trees in the ground, then fertilize with nitrogen fertilizer every spring. If your soil has a high pH, you may see signs of iron chlorosis on the newest growth (yellow leaves with green veins). In that case, include a source of iron and apply as needed. If you are growing your satsumas in containers, then use a slow-release fertilizer designed for containers such as Osmocote, applied in spring just prior to new growth. Slow-release formulations will slowly supply nutrients, but they rarely last all growing season, so a supplemental application of a water-soluble fertilizer every 2 to 3 weeks will keep the tree healthy and support the crop of fruit.
I have enjoyed a bountiful satsuma crop for the last 10 years. I have found out, however, that if you do not thin a heavy fruit set, then they will have very few, if any, fruit the following year. Thinning fruit may be one of the hardest things to do when growing a tree fruit, but it will reduce stress on the tree and help it continue to be productive for many years. Dr. Stein strongly recommends thinning to one fruit for every 12 inches of shoots. I must confess that I have not done that and have paid the price. The price is that your tree will most likely have few or no fruit next year. This is called alternate bearing — getting a crop every other year. Fruit thinning, adequate fertility, periodically repotting trees in containers and regular watering during the summer are all needed for healthy and productive trees.
Besides providing you with delicious fruit in late fall, satsuma trees provide you with extremely fragrant white blooms in the spring. The fragrance is heavenly, and the trees are always abuzz with pollinators. In addition, satsumas will attract female giant swallowtail butterflies seeking leaves on which to lay their eggs. All plants in the citrus family host these beautiful insects. The caterpillars look exactly like unappetizing bird droppings — a perfect camouflage against predators. Well-established trees can easily tolerate a few missing leaves eaten by these interesting creatures.
The main pest I have on my trees in Northeast Texas is leaf miner — the larval stage of a moth. Their damage is mainly cosmetic, disfiguring the newest growth. Dr. Stein recommends the home grower tolerate the damage, since leaf miners are difficult to control and don’t significantly affect the crop.
Due to threat of deadly diseases, only trees grown in Texas can be sold in Texas. Look for satsumas at your local nursery or garden store. Whether you grow them in containers or in the ground, you will enjoy the fragrant, spring floral display, the summertime giant swallowtails cavorting around your trees and the fresh, sweet, satisfying fruit in the fall. tg