Week of August 11, 2003

Calvin Finch, Ph.D., Conservation Director, San Antonio Water System, and Horticulturist

 

Citrus in the Landscape

 

If you were impressed by a neighbor’s Satsuma orange tree growing in a container on the patio, now is the time to purchase your own.  A large number of Satsumas and other citrus are available on the San Antonio market.

 

There once was a Satsuma industry on the Gulf Coast and many area gardeners have had good success growing the sweet, easy-to-peel fruit.  Cold protection is the key to long-term citrus production in the San Antonio area.

 

If you decide to plant the Satsuma in the ground, be sure to plant it near a house or in an area that has access to electricity so a space heater or a string of light bulbs can provide some supplemental heat during those unusually cold nights (below 25 degrees F.)  The tree is normally 15 to 20 feet tall at maturity and can be kept even smaller by yearly pruning.  If pruned yearly to keep the tree height below the eave of the house, a lean-to type structure can be made by draping plastic from the house eave to the ground.  Then supplemental heat sources (light bulbs, space heaters, etc.) can be added.  Understand that the more drastic the cold the greater amount of heat must be furnished to keep the temperature inside the lean-to above 25 degrees F.  Some folks thought that four light bulbs would keep plants warm in 6 degrees F. weather.  Now all these folks have left is a dead Satsuma stick.  Remember that Satsumas are grafted trees and the sprouts that come from the ground are not a “new” tree but merely the thorny rootstock on which the citrus was grafted. Cold protection is necessary if a crop is expected every year since cold weather can defoliate trees without killing them, but there will more than likely be no fruit produced following such a defoliation. Gardeners should be careful to avoid danger of electrical shock when using electrical equipment outdoors!

 

During a hard freeze (12 degrees F.) in ’83, some Satsuma trees didn’t even lose a twig to cold.  Of course, they were covered with plastic and had a portable electric heater under the foliage canopy.  Some families may have been a bit cold but the precious citrus was safe and warm!

 

A minimum of pruning will be required for citrus trees.  Citrus has a tendency to form an apron around the trunk, which helps to protect from both cold and heat.  To try to interfere with this by pruning the lower branches to make them look better will result in reducing the next year’s fruit crop as well as encouraging sucker growth.  In Texas, mulching is beneficial in summer months.  Mulching will reduce the soil temperature and permit the roots to feed the tree normally.

 

The easiest and surest way to avoid the freezing problem is by planting trees in containers that can be rolled into a protected area at the onset of adverse weather.  The Satsuma mandarin is a very worthwhile plant to containerize.  Though the Satsuma is technically a small tree, its size can be dwarfed even more when it is containerized.  Use a large container such as a whiskey barrel or 20-gallon pot.  If the container does not drain well, be sure to insure adequate drainage by drilling or cutting holes in the bottom.  If using a wooden container, attach heavy-duty coasters to help mobility.  Containerized plants that can be stored in garages are easier to keep warm during prolonged periods of cold.  It is more economical to maintain the temperature of a garage above 25 degrees F. than it is to maintain the same temperature in a plastic-covered lean-to type structure on the side of a house.  Invest in a well-drained potting mix (soil) and include the proper amount (triple the amount on the label instructions) of Osmocote Slow-Release fertilizer pellets.  This slow-release fertilizer application should be done yearly in the spring (March.)  Plant one Satsuma or citrus tree in the middle of the container.  Satsumas should be grown in a location that receives as much direct sun as possible.  Watering is gauged by plant size and temperature.  Larger Satsumas require more frequent watering during hot, dry conditions.

 

Other citrus species are also on the market including lemons (Improved Meyer); Oranges (Moro blood, Sanguinelli Blood, Ruby Blood, N-33 Navel, Navel, Everhard Navel, Skaggs Bonanza Navel, Valencia, Mars, Joffa); Mandarins or Satsumas (Okitsu Wase, Seto, Miho, Dancy, Sunburst, Clementine, Page, Kishu, Kinnow); Grapefruits (Rio Red, Henderson); Tangelo (Temple Tangor, Orlando). 

 

I have grown Meyer lemon in a container for years, but remember, Satsumas are the most cold tolerant citrus, all of these other species will require you to mobilize your cold protection strategy when freezing temperatures threaten.