Grapefruit Cultivation: The Realities of Back Yard Grapefruit Tree Growing

Grapefruits can be grown on every continent except Antarctica. It is just a question of making sure that proper growing conditions are in effect. Anyone who fantasizes about hand-picked fresh grapefruit will find that dream realized by giving a growing grapefruit tree plenty of space in which to receive specified levels of incoming heat, light, moisture and nutrients.

1. Adequate heat, with temperatures ranging from 60 to 75 °Fahrenheit (15.55 to 23.88°Celsius):

At the upper range of warmth, the time from flowering to mature fruiting may be only 7 to 8 months. At the lower range, it may take as much as 13 months. At the upper range, the fruit will be less acidic in taste whereas at the lower it will be more so.

As a general rule and because of their warm temperature proclivities, grapefruit cannot be counted on to survive outside where the ground freezes and where temperatures remain below 50°F. (10°C.) for extended periods.

Nevertheless, grapefruit are known to survive temperatures as low as 20°F. (-6.66°C.), as long as such occurrences are rare exceptions to the above-mentioned rule. Damage from such temperature aberrations can range from leaf drop to retarded new growth and smaller or stunted fruits. But generally, the plant knows how to compensate once temperatures warm up. The exception may be if the chill lasts longer than 3 to 5 hours at a time, in which case ice can form inside the fruit, which then becomes inedible.

Any time temperatures drop below 28°F. (-2.22°C.), grapefruit tree growth can be protected by frost protection measures. Effective responses include blankets to be spread on the ground below the tree as well as sacking to be draped over stakes and to cover the tree from the canopy crown down to the root flair.

2. Adequate light, with at least seven hours of daily sunlight:

Moisture loss rather than sunburn can be a problem on sunny days when temperatures go over 80°F. (26.66°C.). A preventive measure is locating grapefruit trees in wind-protected, southerly or westerly locations on a property. As an ornamental houseplant, the tree still may show similar sensitivity to heat and light extremes inside. It therefore will do best as the recipient of sunlight reflected off light colored walls instead of direct sunlight in front of unadorned windows.

3. Adequate rainfall, evenly distributed throughout the year:

The ideal range is 36 to 44 inches (91.4 to 111.7 centimeters). The peel will be thinner and the fruit juicier at the upper ranges. It will be thicker and less juicy at the lower ranges.

4. Adequate drainage:

Grapefruit trees benefit from soil which remains slightly moist, but not waterlogged, from the surface to six inches (15.24 centimeters) down. Generally, supplemental watering only has to be carried out every 7 to 10 days depending upon the lack or prevalence of rainy weather. Soil is moist enough if freckles of dirt dot a soil probe after being plunged into the ground. It is too moist if the probe turns up muddy.

5. Adequate soil pH levels between 6.0 and 8.0:

Grapefruit can grow in mildly acidic sand, particularly if regular treatments with magnesium sulfate and crushed limestone head the soil pH towards the mildly acidic level of 6.0 or the neutral level of 6.5. Otherwise, magnesium may become deficient in more acidic soils, older leaves may turn pale in color along the margins and tips and between the veins, and twigs may weaken and die.

Grapefruit can grow in alkaline soil with pH levels up to 8.0, even though supplemental watering schedules may cause alkaline salts to rise to ground level and slow nutrient uptake by the tree’s roots. Additionally, copper, manganese and zinc deficiencies may require copper, manganese and zinc sulfate applications when the soil pH level heads to the upper alkaline range. Otherwise, young leaves respond with a pale greening between the veins when deficient in manganese and zinc, the latter of which also stunts foliar length and width. Leaves, peel and pulp turn out misshapen and brown-spotted in the case of copper deficiencies, which may occur in acidic soils as well.

6. Adequate soil texture:

Soil contains a greater or lesser presence of clay, sand and silt. Each grainy texture has advantages and disadvantages. For example, clay is strong on fertility, but weak on drainage. Sand is strong on drainage, but weak on fertility. Silt is strong on drainage and fertility.

Generally, loam incorporates the best of all soil particle worlds. It in fact makes ideal soil conditions available to cultivators and gardeners through its composition as 20% clay, 40% sand, and 40% silt. But land that does not have loam need not be written off as an environment hostile to grapefruit trees.

For example, grapefruits are being grown successfully in the challenging clay soils of humid, warm Suriname (Dutch: Republiek Suriname) in northern South America. Clay generally can be considered as problematic for growing grapefruit trees. Specifically, it holds water and drains slowly. These two characteristics promote a too moist soil level for grapefruit tree roots, which are prone to root rot. Suriname's solution rests on resistant rootstocks, such as Citrus Sunki mandarin and King mandarin, both of which additionally support high yields of quality fruit.

7. Adequate soil nutrients:

If the soil is indeed loamy, then the grapefruit tree may not be too demanding for supplemental feeding. Compost as 2 to 3 inches (5.08 to 7.62 centimeters) of ground cover may be sufficient if properly applied. Specifically, it must begin no closer than a foot (30.48 centimeters) from the tree flair. It then must come into contact with lawn grass no closer than on the other side of the tree canopy’s drip line.

The drip line in fact is an imaginary circle which plots and connects the points on the ground immediately below the tips of the tree's longest spreading branches on all sides. It is important since the surface spots identify the subsurface occurrences of the tiny end feeder rootlets by which tree roots take in soil moisture and nutrients. The drip line therefore pinpoints critical interaction points between fertilizers and tree roots.

Otherwise, those who face less than optimal soil textures or who prefer fertilizer schedules can apply one annual cup of aluminum sulfate (21-0-0-24) per year of life of the tree. The preceding numbers in parentheses indicate the relative presence or absence of nitrogen, phosphorus, potassium and sulfur. Nitrogen, with the chemical symbol N, is given first. Phosphorus (P), Potassium (K) and Sulfur (S) percentages number second, third and fourth.

The fertilizer treatment is divided within each year into three separate applications. So one-third each of one cup in the first year, of two cups in the second, etc., is given in February, May and September. Each time, the fertilizer is scattered on the ground and then soaked into the soil and plant roots by an immediate supplemental irrigation.

8. Adequate spacing:

A grapefruit tree’s root system continues to grow along with all other body parts throughout the woody plant's life span. In fact, it ultimately may spread two to three times underground the amount of space cast above ground by the tree canopy’s shadow. Its shallow root system may turn in backward girdling patterns or upward heaving movements when moisture, nutrient and spatial requirements are not being met. The distance marked off from the seedling or transplanted tree’s trunk therefore must be at least 15 feet (4.57 meters), in all directions, from other seedlings or trees and from such structures as the nearest buildings, driveways fences, sidewalks and walls.

9. Adequate propagation:

Grapefruit trees may be grown by budding, cutting, grafting or seeding. In terms of the latter, place the seeds inside a Ziploc plastic bag of equally proportioned, moistened growing medium, such as bark, peat moss and soil. Keep covered and moist in a warm, sheltered place at 65 to 85°F. (18.33 to 29.44°C.) for 10 to 21 days. Plant germinated seeds one-half inch (1.27 centimeters) down in pots of citrus tree starter soil. Report whenever the container width is less than 2 to 3 times the height of the growing plant. Transplant in fall.

An advantage of seedage is the grapefruit's high degree of nucellar embryony whereby multiple embryos are produced as clones of the original embryo. As a result, seeds grow true to type so that the seedling is like the parent. But one disadvantage is seedling susceptibility to Phytophthora disease in both its foot and root rot forms. Another disadvantage is delayed viable fruit production to anywhere from the seventh to the ninth or tenth years, in comparison to the third year with budded rootstock.

In terms of the United States of America, the preceding cultivation conditions definitely can be met outdoors in the states of Arizona, California, Florida and Texas, but with different market impacts. Specifically, grapefruit is considered legally mature 7 to 14 months after the trees bloom in spring. Fruit from Florida and Texas therefore show up in markets from October through June while Arizona grapefruit ripen from January through September and California grapefruit from February through November.

Florida consistently claims leadership among the four above-mentioned states in terms of highest and most profitable levels of grapefruit production.Texas nevertheless confers upon the grapefruit a hallowed status as a special edible which cooperates in making year-round fresh supplies available for year-round customer demand. The lone star state in fact has the grapefruit in its delectable, juicy, seedless red form as the official state fruit.

Specifically, on May 17, 1993, then Governor Dorothy Ann Willis Richards (September 1, 1933 – September 13, 2006) signed House Concurrent Resolution No. 75 of the 73rd Texas State Legislature:

"WHEREAS, The State of Texas has traditionally recognized a variety of official state symbols as tangible representations of the proud spirit and heritage of our state; and

WHEREAS, The bluebonnet, the pecan tree, and the mockingbird are examples of natural specimens that serve to exemplify the great diversity of the Texas landscape, while the state dish, chili, fittingly represents another aspect of our shared culture as Texans; and

WHEREAS, In keeping with this custom, the designation of the Texas Red Grapefruit as the official State Fruit of Texas will provide suitable recognition for this outstanding food resource; and

WHEREAS, First discovered by Texas citrus growers in 1929, this variety of grapefruit has been carefully nurtured and perfected over time and is renowned for its sweetness and rich, red interior; and

WHEREAS, As nutritious as it is palate pleasing, the Texas Red Grapefruit contains no fat or sodium, lowers high levels of blood cholesterol, boosts iron absorption, is low in calories, and is rich in vitamin C; and

WHEREAS, This delicious fruit also is a boon to the state economy, generating more revenue than any other tree fruit produced within our borders; and

WHEREAS, As distinctive as the proud state from which it originates, the Texas Red Grapefruit will serve as a fitting emblem for the bounties of nature with which our state is blessed; now, therefore, be it

RESOLVED, That the 73rd Legislature of the State of Texas hereby designate the Texas Red Grapefruit as the official State Fruit of Texas."

This article is dedicated to the memory of my paternal grandfather, August, who added owning a grapefruit orchard in Dunedin, Florida, to his impressive list of accomplishments. Although he predeceased my birth, I know of his admirable qualities through his son, my father, and I remember grandfather August and his poetic reverence for life every time I am in the presence of grapefruits.

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

grapefruit Citrus x paradisi Macfad. (pro sp.) [maxima × sinensis]: Kenneth M. Gale/Bugwood.org, CC BY 3.0, via Forestry Images @ https://www.forestryimages.org/browse/detail.cfm?imgnum=4322212

"Melanose of grapefruit near Kea'au, Hawaii.": Scot Nelson, Public Domain, via Flickr @ https://www.flickr.com/photos/scotnelson/5816017577/

ca. 1930 black and white photograph: WaterArchives.org (waterarchives), CC BY SA 2.0, via Flickr @ https://www.flickr.com/photos/waterarchives/5661418492/

Cam sành: Hoc Tri Thuc, Public Domain, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Camsanh.jpg

grapefruit: aprilandrandy, CC BY-ND 2.0, via Flickr @ https://www.flickr.com/photos/aprilandrandy/256725780/

grapefruit: aprilandrandy, CC BY-ND 2.0, via Flickr @ https://www.flickr.com/photos/aprilandrandy/256725780/

Texas governor Ann Richards in 1992: Kenneth C. Zirkel, CC BY-SA 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Ann_Richards.jpg

"ruby red": jasleen_kaur, CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/jasleen_kaur/5168517360/

March 1949 photo by U.S. Navy: Florida Keys-Public Libraries, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/keyslibraries/8150974021/

photo donated by Lois Simpson: Florida Keys-Public Libraries, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/keyslibraries/4890316755/

"Monk and grapefruit tree": dorothy.voorhees, CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/dvoorhees/3240998765/

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Brussel, E.W. van. "Interrelations between citrus rust mite, Hirsutella thompsonii and greasy spot on citrus in Surinam." Agricultural Research Reports 842. Wageningen: Centre for Agricultural Publishing and Documentation, 1975.

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