A Simple Guide on How to Grow and Care for Ponderosa Lemon Trees

How to Grow and Care for Ponderosa Lemon Trees
The Ponderosa lemon tree is famous for its attractive appearance and its huge, five-pound lemons. But that doesn't mean it is difficult to grow, as you will learn. We'll tell you how to grow and care for a Ponderosa lemon tree.
Gardenerdy Staff
Last Updated: Feb 27, 2018
Did You Know?
A single Ponderosa lemon is sufficient to make several pitchers of lemonade.
The Ponderosa lemon tree, despite its name, is not a true lemon tree. It is a citrus plant that is a hybrid between a citron (another citrus plant) and an ordinary lemon tree. It is popular for its huge 4 to 5 pound fruits, which have the appearance of a citron, but taste like a lemon. They have a thick, wrinkled rind, and seedy flesh. The fruits serve as a perfect culinary replacement for lemons, and can be used in jams, lemonades, pies, and other recipes.

The Ponderosa lemon tree was discovered by George Bowman, in 1887, in Hagerstown, Maryland, which soon became popular all around the US by the name of 'American Wonder Lemon', owing to its large fruit. It is a slow-growing tree, which, when fully grown, can reach a height of 24 feet, and spread out to a width of 10 to 12 feet, though it is much smaller when grown in containers. It grows in the USDA hardiness zones 9 to 11, and can be grown from both, seeds and cuttings.

Though the tree is not cultivated commercially, it is gaining popularity as an ornamental plant because of both, its attractive appearance and the diverse uses of its fruit. The tree bears fruit throughout the year, which can be left on the tree for several months without loss in flavor or quality. The plant is self-fertilizing, and can be pollinated by simply rubbing a paintbrush on its flowers. Let us now see how to grow and take care of the Ponderosa lemon tree.
How to Grow Ponderosa Lemon Trees
► Prepare a potting mix by combining equal amounts of peat moss, perlite, and sterile pot soil in a pot which is one size larger than the growing container. A pot of 5-gallon capacity is ideal. It should have a hole at the bottom.

► Transfer the plant from the growing container, or a cutting, to this pot, making sure that the soil level in the pot is the same as that in the growing container. Leave about an inch of space at the top, to allow watering.

► Take a small container and fill it with large pebbles, followed by pouring a little water, such that the pebbles are not completely immersed in it. Keep the pot on top of the container of pebbles, which provides humidity.

► Water the plant thoroughly, but without making the soil soggy. Allow the soil to dry out before the next spell of watering.

► Apply a good indoor citrus fertilizer twice a month, till the plant grows actively.
► Select a location which receives a good amount of sunlight and has well-drained soil. It should be around 20 - 30 feet away from any structure to allow proper air circulation. Uproot all weeds and grass from a 2-foot section of the soil, as they might compete with the plant.

► Take the pot which has the Ponderosa lemon tree and topple it sideways. Gently lift the plant from the scattered soil, and by spraying water from a garden hose, clean off all the soil around its roots.

► Dig a hole in the ground, which is twice the width and of the same depth as the pot. Place the tree in it, ensuring that the bud union is a couple of inches above the soil.

► Fill half of the pit with soil, followed by thorough watering. Then, fill the pit completely. Compact some soil at the base of the stem, such that it is about an inch higher than the ground.

► Place a 3 to 4 inch-thick layer of mulch, such as wood chips, hay, or leaves around the tree, ensuring that it does not come in contact with the stem, and extends all the way till the drip line.

► Using some garden soil, create a 'watering ring', by compacting soil in a circle 2 feet away from the base. It should be 3 - 4 inches high, and 7 inches wide. Water the plant in the ring. If any holes are visible around the root, fill them with soil.

► Water thoroughly once every two or three days for the first month. Reduce this to once every 4 or 5 days during the next couple of months.

► Apply ammonium sulfate fertilizer once in the first year after new growth appears on the tree, and twice in the following year.

► Eventually, the watering ring will gradually melt down, and at this stage, the tree can be considered to be established in the soil.
How to Care for Ponderosa Lemon Trees
The Ponderosa lemon tree is not drought-resistant. Watering should be frequent after planting, and only periodic later on. Deep and thorough watering is preferable to shallow and regular watering. It is advisable to water the plant only when the soil surface feels dry to touch. Do not allow water logging under any circumstances, as this can cause root rot, which can kill the plant.

Potted plants can tolerate more water, since the pot drains away the excess amount. In fact, container plants can be watered once or twice daily in warm weather. On the downside, these plants are more susceptible to drought. Watering should be less frequent during the colder months. Choosing too large a pot too soon, called 'over potting', can lead to over-watering, and may cause root rot. It is one of the chief causes of pest infestation and disease.
The tree prefers well-drained soil, since soggy soil can cause water logging. The soil can be neutral or slightly acidic, with a pH between 5.5 and 6.5, so a pH test is advisable. Sandy soil is fine, but this has less nutrients and needs more frequent watering, though the plant can survive even in poor soil. A mixture of garden soil, sand, and compost, in equal measures, is ideal for a potted plant, as this solves the problem of nutrients, along with providing good drainage.

The Ponderosa lemon tree can survive in loamy, sandy, or clay soils. The soil may develop a high salt-buildup if not watered adequately. Applying and regularly replacing a thick layer of mulch in outdoor plants is recommended, as this provides nutrients by gradual decomposition, besides allowing slow percolation of water, by trapping it. It also prevents weeds from growing around the plant.
The tree needs good sunlight for rapid growth and reproduction. Indoor potted plants can be exposed to grow lights to cut the light deficit, especially in the northern states which receive lesser hours of sunlight, or can be placed at a sunny, south-facing window, especially in winter. Eight hours of sunlight is the daily recommended exposure, but a minimum of 5 to 6 hours is essential. Potted plants can even be kept outdoors in full sun, provided that they are protected from the wind.

Beginning in spring, they should be first acclimatized by keeping them in a warm, shady spot outdoors in the mornings, followed by bringing them indoors during the hotter parts of the day, and again leaving them outdoors at night. After a few days, they can be left outdoors continuously, until fall. However, when temperatures soar to 100ºF or higher, then it's wise to shift the plants into some shade, or cover them with a shade cloth. At such high temperatures, the tree bark may get sunburned.
Being tropical in nature, this tree requires warm temperatures, and is less resistant to frost, when compared to the other citrus plants. Temperatures below 32ºF will cause the foliage to develop frost burns, and even death, if exposed to temperatures of 28ºF or lower for several hours. Potted plants should be taken indoors during winter, but can be kept outdoors when temperatures rise above 55ºF.

During winter, outdoor plants can be covered with blankets or cardboard, ensuring that warm air does not escape, and holiday lights can be placed around them at night. The minimum-recommended winter night temperature is between 40 to 50ºF, with an increase of 5 to 15ºF during daytime. In general, the plant requires a daytime temperature of about 65ºF, and a nighttime temperature of between 55 to 60ºF, in all seasons.
Adequate fertilizing will ensure good growth and yield of the plant. A fertilizer like ammonium sulfate, an indoor, citrus liquid water-soluble fertilizer, or a balanced fertilizer of 20-0-0 formulation can do the job. It should be applied by scattering it around the base of the plant, followed by watering. Watering is essential for two reasons: one, that it takes the fertilizer all the way to the roots, and two, it prevents root burns caused by strong fertilizers.

The recommended dose is one cup during the plant's first year, followed by an increase in one cup, both in the second and third years. Fertilizing should be split up into three applications; one each in February, May, and September. The tree should receive as many cups per year, as its age in years.
The pruning required is minimal, as the natural shape of the plant is attractive and upright. Prune any dead, diseased or interlocking branches that might block sunlight from reaching the inner part of the tree. This is because, more exposure to the sun equals a better yield. For this reason, the branches are maintained in a scaffold-like structure, where sunlight reaches the interior.

Branches that appear on the lower limbs of the tree should be removed, as they change the scaffold structure. Remove any root sucker which appears at the base, as it drains away nutrition that can be better used for growth and fruiting. Adequate pruning will prevent the branches from snapping under the weight of the lemons. It is vital to regularly prune all canopy edges to promote better growth. You can also remove the thorns, if desired. Pruning should be carried out before spring, when the plant begins vigorously growing.
The Ponderosa lemon tree is attacked by various pests, like aphids, mites, whiteflies, cutworms, and scale insects, which reduce its vigor. The easiest remedy for this is to 'blast' these pests away using a spray from a garden hose. One can also apply a horticultural oil, such as neem oil, or an insecticidal soap regularly. Though, in most cases, these insects have their own natural predators which kill them, so the infestation may not need external control always. Indoor potted plants can be shifted outside temporarily for the predators of the pests to come and do their job.

Diseases like citrus stubborn disease, citrus black spot, Alternaria, root disease, and citrus gummosis may also target the tree. Most of them are transmitted to the plant by the above mentioned pests, or caused by over-watering. Therefore, control of pest infestation, good fertilizing, and maintaining adequate soil drainage will go a long way in protecting the tree.
In conclusion, the Ponderosa lemon tree can grow well in temperate regions, despite being tropical in origin. If given good sunlight, drainage, and warm temperatures, this tree can very well take care of itself.
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