Saturday, August 9, 2003

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

 

CITRUS IN SAN ANTONIO

 

            If you have always wanted to grow your own citrus, now may be the time. Supplies this summer are at the highest levels they have been in years. Check out your local nursery, H.E.B., Home Depot, Wal-Mart, and Lowes. Lemons (Improved Meyer), oranges (Moro blood, Sanguinelli blood, Ruby Blood, N-33 Navel, Navel, Everhard Naval, Skaggs Bonanza Navel, Valencia, Marrs, and Jaffa), satsumas (Kinnow, Kishir, Dancy, Sunburst Page, OkitsuWase, Sato, Miko), grapefruits (Red, Henderson), and tangelos (Orlando, Temple Tangor) are available.

            Satsumas are the hardiest of the citrus varieties on the market and the easiest to grow. Satsumas are the sweet, mild mandarin oranges we import from Japan in those small cans and use in salads.

            Even satsumas are sensitive to cold weather. If you want to enjoy their blooms and fruit more than one year, be prepared. A cold night after a mild fall can put all your efforts to an end very quickly. If you decide to plant the citrus 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 stick. Remember that citrus are grafted trees and the sprouts which 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. There will more than likely be no fruit produced following such a defoliation. Plant protectors should be careful when using any electrical equipment outdoors!

Citrus trees do not require much pruning. Citrus 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 will result in reducing the next year’s fruit crop, as well as encouraging sucker growth. In Texas, mulching is beneficial in the summer months. Mulching will reduce the soil temperature and permit the roots to feed the tree normally. Citrus are very drought resistant but, for maximum fruit, do not let them dry out severely.

The easiest and surest way to avoid freeze damage is to plant trees in containers which can be rolled into a protected area at the onset of cold weather. The Satsuma mandarin is a especially worthwhile plant to containerize. The Satsuma is a small tree and its size can be dwarfed even more when it is containerized. Use a large container such as a whisky barrel or 20-gallon pot. If the container does not drain well, acheive adequate drainage by drilling or cutting holes in the bottom. If using a wooden container, attach heavy-duty coasters to help provide mobility. 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 and transplant a trailing type of lantana or flowering annual plant (petunia, periwinkle, pansy) to fill in the rest of the perimeter planting space in the pot. Flowers will eventually cascade over the side of the container producing a beautiful display. Satsumas should be grown in a location which receives as much direct sun as possible. Watering is gauged by plant size and temperature. Larger satsumas with more perimeter color plants require more frequent watering during hot, dry conditions.

Containerized plants which can be stored in the garage 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.

The main problem most people have with Satsuma is waiting until the fruit turns orange in October to harvest it. The fruit is actually sweet when the skin is still green in September. The longer the satsuma fruit can stay on the tree without freezing, the sweeter the fruit will become. Most citrus will naturally fall from the tree in February and March if not harvested.