Gardening with Gary

Gardening Advice from an Expert

Lemon Trees

Q. How do I grow a lemon tree? Where are they from anyway?

Here is some basic information for you. If you need pages of research and directions for growing in details, consider checking your local library under 'Gardening' or 'Citrus Trees'. Best of luck with this fine fruit tree!

Lemon trees can reach a height of 22 to 25 feet (6.7 to 7.6 meters). They are very thorny and have long, pointed, pale green leaves. The trees produce purple-tinged white, fragrant flowers. Lemons develop from the ovaries of the blossoms and ripen about 7 to 8 months after the flowers bloom.

Lemon trees often have blossoms and fruit at the same time. Lemon trees are grown from buds cut from trees that produce the type of lemon desired. The buds are grafted to seedling lemon trees called rootstocks. Rootstock varieties are chosen for their resistance to disease and for various other reasons.

Lemon trees start to produce fruit about two years after grafting, and some continue to bear fruit for 50 years. Lemon trees may be severely damaged by frost and freezing temperatures, and growers use many methods to protect the trees from cold weather. For example, some growers prevent frost by warming the cold air near the ground with oil-burning heaters. Other growers use large fans called wind machines to mix the cold surface air with the warmer air above it. Water sprays under the trees also help protect against cold.

Lemon trees may also be attacked by such pests as mites, scale insects, and thrips. Mites and scale insects feed on the leaves, fruit, and twigs of the trees. Thrips attack the buds and the fruit. Growers combat such attacks by growing varieties of trees that resist pests and by spraying the trees with insecticides. They also spray orchards with fungicides to fight fungal diseases, which attack the leaves, fruit, and roots of the trees.

Lemon trees bear fruit throughout the year, and growers harvest the fruit 2 to 10 times a year. The largest harvests occur in the autumn and winter. However, lemons are commonly stored for several months. Lemons to be sold as fresh fruit are picked before they reach full size and maturity. Then they are stored under special conditions so that they are less likely to be damaged during shipment and are more attractive than those shipped immediately after harvest. Decay can be a problem during the marketing of fresh lemons. Blemished lemons and ones that are too mature at harvest are sent directly to factories for processing.

Lemons probably originated in northeastern India, near the Himalayas. Lemons were taken from India to Italy by the Arabs in the AD 100's, and to Spain in the 1100's. In 1493, the Italian navigator Christopher Columbus planted the first lemon trees in America. By the late 1700's, Spanish missionaries had taken lemon trees to California. The first commercial lemon orchards in the United States were planted in the late 1800's.

Scientific Classification. Lemons are members of the rue family, Rutaceae. Commercial lemons belong to the species Citrus limon.

Wilfred F. Wardowski, Ph.D., Professor of Horticulture, University of Florida Citrus Research and Education Center. "Lemon," Discovery Channel School, original content provided by World Book Online

Barbara, Delaware writes~
I have a 47 yr. old lemon tree that is an indoor plant. It has developed scale very badly. Since this plant has a lot of sentimental value to me I would like to save it. Any suggestions?

A. My best wishes, but scale is so very hard to get rid of. Scale insects are particularly difficult to manage because as the insects mature, they settle down to feed on the plant at a single point. They build a waxy covering over themselves. This covering protects them from the environment and our insecticides. Before they settle down, the juvenile insects are called "crawlers". In the crawler stage they are much more susceptible to application of insecticides.

HORTICULTURAL DORMANT OIL TREATMENT
(Scale Insect Control) This is a highly refined superior spray oil for the control of scale in its immature stage. Susceptible plants to scale are euonymus, mugo pines, tropical citrus, magnolias and many foundation plantings.

http://www.funklawncare.com

Sanitation, removing fallen infested leaves and pruning severely infested branches, is another important aspect to treatment. Pruning and raking reduces the opportunity for reinfestation following spray treatments.

Here are steps for eradication:

1. Remove only dead or completely yellow leaves. Your plant needs all of its green leaves to produce energy for its recovery.

2. If the white covering of scale insects is very thick, spray the leaves and stems with a jet of water to wash away as much of the covering as possible. Adjust the spray to a level that does not damage the leaves.

3. After the plant has dried, read the insecticidal oil label, mix and spray accordingly. Be sure to cover the scale thoroughly, especially on leaf undersides.

4. Repeat the insecticidal oil spray weekly for four to five weeks. The oil does not kill insect eggs and you must kill new hatchlings.

5. The dead scale will not fall off plant easily and new scale insects will find your plant again. Check for live scale by rubbing your finger across the white covering. If you see an orange coloration on your finger, some of the insects are still alive and you should start the spray program again.

The typical insecticidal oil is a petroleum product designed to kill insects without harming plants. It works by covering and suffocating the insects, not by poisoning them. It is less toxic to people and animals than most insecticides and the scale cannot develop a resistance to the treatment. Oil must be applied five times, a week apart and still there is no guarantee.

Assistance: Fairchild Tropical Garden

Stefanie writes~
I have a Meyers Lemon tree that I planted in a large tub last year. The tree is doing great, however, I notice that the leaves are all curled up a couple of weeks after they sprouted. Is this normal?

A. No not at all. Meyers Lemons are delicious lemons that can grow in many environments provided they get very good light and plenty of water. These lemons have a rich fragrance and flavor all their own. These trees bloom year-round giving a spectacular array of purplish-white flowers and a beautiful aromatic scent as well!

Discovered in China in early 1900's. This compact variety flowers and fruits prolifically with medium-sized juicy fruit of good flavor and delightful fragrance.

Lack of water can put it into shock resulting in rapid leaf drop and curling. It could take some weeks for it to recover. Do not add any fertilizer while it is under stress, as that will just cause more problems. If it is not a young tree, it should bounce back, but there may be some trimming needed for dead branches after a while. Also if it survives, make sure that you check it carefully all the time to make sure there are no aphids, scale and red spider mites which can really do some damage while it is weak.

Have you checked for spider mites, their number one pest? There will be tiny fine webs around the leaves and stems with tiny black dots. Give it a good hard spray with a hose, then spray it with insecticidal oil which should be used as annual or semiannual maintenance on Meyer Lemons.

Meyers Lemon trees are pretty resilient if you give it good soil conditions [well-drained and organic] and sun. They will generally repair itself more so than other citrus trees.

Pearlene writes~
I have lived in Lincoln, CA for four years and so far have tried to grow a Meyer and Lisbon lemon with no success. I'm determined to have a tree eventually, even if I have to put it in a large pot and put it inside when we know we will have a freeze. We live in the Lincoln countryside and we're told by neighbors that we have our own micro-climate and it gets too cold to grow lemons. I planted a Lisbon lemon because I've been told it's more frost resistant. Any more suggestions would be welcome as to variety, size, etc. And the pink lemons; are they found around here? If I do not plant one, at least I'm learning.

A. A variegated Pink Lemon Tree has cream and light green leaves, the fruit is yellow, but pink inside. This lemon variety is available at Excalibur Rare Fruit Nursery in Lake Worth. They have many unusual citrus varieties. The tree is striking with its white and green leaves. It is a variation of the Eureka lemon, and can be treated the same way. It will not bear as many fruit, but may bear 30-50 lemons a year when it is full grown. It is fairly frost hardy, possibly to 25F without damage other than losing some leaves. It can bear fruit when only 4' tall. The fruit is pink inside and the outside also variegated. The taste is very non-acidic, sweeter than regular lemons. Lemons need deep watering and applications of mixed trace elements and water every 3 months for 1 year. Carbaryl is used for caterpillars and Dimethoate (Rogor), diluted as per label instructions, will fix a leafminer problem. If you have clay soil, the plant could be waterlogged. Apply dolomite lime around the base of the tree over winter. This will at first make the tree a little yellow and then as the lime works in, the leaves will green. Dolomite creates good soil structure and reduces the acidity caused by the heavy feeding that lemons require.

Assistance from: Garden Web

Greg writes~
I have a Lemon Tree (3 years), Key Lime Tree (1 year) and an Avocado Tree (2 years.). How do I graft to bear fruit and where do I get the grafting?

A. Grafting is a complicated task not one easy for an answer here, so I did some searching and found a good website with color pictures illustrating where cuts are made, how attached, and the reasons and descriptions. Using fresh graftwood, and a sharp budding knife, make a sloping basal cut about 4 - 6cm long on one side of the graft stick. A second cut of about 2cm long is made on the opposite side so that the end of the stick is tapered. Finally a third cut is made to take a sliver off one side of the tapered base. Wrapping the graft stick in cling wrap, and covering the grafted limb with a brown paper bag, stopped the graft sticks drying out and kept them cool. The most important factors determining the success of the techniques appear to be the use of fresh healthy graft wood, the tight binding of the graft stick to the stump, and protection of the graft from dehydration

Jack writes~
We have a lemon tree that just did survive this past years freeze in Alabama and is now sprouting furiously. My wife wants to know what she can do to improve its survivability as an outdoor tree. What kind of soil treatments does it need to improve its root base?

A. Lemons need deep watering and applications of mixed trace elements and water every 3 months for 1 year. [Carbaryl is used for caterpillars and Dimethoate (Rogor), diluted as per label instructions, will fix a leafminer problem.] If you have clay soil, the plant could be waterlogged. Apply dolomite lime around the base of the tree over winter. This will at first make the tree a little yellow and then as the lime works in, the leaves will green. Dolomite creates good soil structure and reduces the acidity caused by the heavy feeding that lemons require.

Assistance from: Garden Web

Tamra writes~ I had a Eureka lemon in a pot that was budding, when the leaves turned yellow and dropped off. I moved it into the ground and it's doing great. Now I have a dwarf lime in that same pot, it has lots of buds, and the leaves are turning yellow again around the edges. I live in Southern California, the pot gets plenty of light and water. Any ideas what causes the yellow?

A. The leaves have been turning completely yellow and falling off due to over/underwatering, lack of nitrogen or lack of iron. Leaves usually drop closest to the trunk, leaving some foliage at the ends of the branches. Epsom salts at about 1T per gallon helps. Buy a soil tester kit, which may confirm a lack in nitrogen and possibly that the soil is alkaline, while citrus prefer acidic soil mix. Add nitrogen as per directions. Also, three major trace elements that citrus require will not be available at a high pH [alkalinity]: iron, zinc and manganese. They are not soluble at a pH greater than 7.0, so unavailable to tree when applied in a soil with high alkalinity. Add chelated Iron/Zinc/Manganese and spray the leaves [foliar spray application] if a deficiency occurs. Consider also Ammonium Sulfate [21-0-0] and a high acid fertilizer. You can also incorporate in the soil some sulfur which will help with alkalinity. Yellowing leaves may indicate poor drainage, a major problem in container growing. Try lightening soil with perlite and bark. Add manure, a citrus soil blend and a little peat. Use a slow release fertilizer. Follow the instructions. Scott's citrus tablets are great. Citrus trees are heavy nitrogen feeders, so make sure there is more nitrogen (N) than phosphorous (P) or potassium (K). Leaves will also drop off with extreme swings in temperatures and very dry air [low humidity]. Early morning tap water misting helps. Every few years refresh the soil, prune the roots and feed, resulting in a lovely tree for many years.

Assistance from The Garden Web

Mrs. Wheat writes~ I have a lemon tree about 5 or 6 years old that suddenly one year produced very large (grapefruit sized) fruit. They are also deformed. With just normal care and feeding it has continued to do this. What's wrong? What can I do?

A. There are two possibilities which come to mind and through research. One is that the citrus tree cross-pollinated with a grapefruit and this fruit is the resulting progeny. If that is the case, there is nothing you can do. Have you seen a nearby grapefruit tree? If certain that there is none, even a few doors down, then you may have the citrus mite, which causes deformities in lemons. The mites feed inside the buds, killing them or causing a rosette-like growth of the subsequent foliage and distortion of flowers and fruit, which may reduce yield and or fruit quality. The mites cannot be seen with the naked eye. They may be found on the plant throughout the year, but their numbers will decrease markedly if conditions are extremely hot and dry. Adult are yellowish or slightly pinkish and worm-like. This is a species limited to Citrus fruits. The mite feeds on buds, sheltering under the scales. The female lays about 50 eggs which hatch after 2-5 days. Remove any minor infested parts of the plant. Where the plant is heavily infested spray with Microfine Wettable Sulphur.

I have two Meyer lemon trees and they get blooms and the start of a lemon and then they turn black and the lemons fall off. One tree is 1 year old and the other one was bought this spring. Any suggestion would be appreciated.

A. Meyer Lemons dropping from plant: Use 1/2 cup of blood-products/bone meal as a fertilizer. Zinc deficiency causes stunting of twigs, reduced flowering, premature dropping of fruit, and yellow bands along the leaf veins. Concentrates or fertilizer is better applied in small amounts, but more often. This decreases the risk of burning. Moving a citrus from one place to another can also be the cause of fruit drop, a common occurrence. Allow the plant to acclimate to any new conditions. As with any flowers, they need to be pollinated. You can use a small paintbrush for this. Give ample sun and water it weekly or as needed. Humidity is a key for all citrus trees. If the air has been dry [there is no mention of where the tree is growing], then the fruit will drop long before mature. Other serious problems are fungus attack, stem-end rot or molds. Take a few pieces of fruit and any leaves with black spots or mars, place in a clear plastic bag and take to your local Ag Inspector or Ag College/University. There the blackness can be analyzed as to if an organism is causing this dropping.

http://forums.gardenweb.com/forums

Gerald writes~
I have a lemon tree that is 7 years old. 4 years ago it stopped blooming and bearing fruit. Any suggestions?

A. You may wish to grow another tree nearby so that there is cross-pollination to produce fruit. If the tree is flowering well, then it is not being pollinated. You need insects as bees or flies to perform the task. Be careful not to eradicate their nesting areas with insecticides. Test the soil with a simple kit you can obtain from a garden center. Citrus fruit needs acidic soil, that is below pH 8.0. If your soil tests alkaline, above 8.0, then apply citrus amendments and fertilizer available locally. Read the packages for rate and frequency of application. Finally, check for any evidence of disease or insect attack. If portions are in question, bag pieces and take to your local agriculture inspection office for analysis.