Growing Citrus Background

GROWING CITRUS

In The ground

For gardeners in warm, temperate areas with light frost.

Growing citrus trees in the ground can be immensely rewarding, and it naturally produces the biggest and most vigorous specimens. However, before planting a citrus tree in the ground, you must determine whether or not the location you have in mind will provide a suitable home for your new dwarf citrus tree.


How Will Citrus Look In My Yard?
Sometimes people aren't quite sure about using citrus as a landscape plant. In fact, citrus work extraordinarily well in most any landscape, offering beautiful evergreen foliage, lovely (and fragrant) blossoms, and colorful fruit.


Size
Citrus trees purchased through our mail order website are all grafted on semi dwarf rootstocks that are perfect for container growing. If planted in the ground dwarf trees can be expected to reach Semi-Dwarf size – up to around 16 feet in height, depending upon variety. In a pot, the semi dwarf trees will stay much smaller, especially with judicious pruning. Standard size citrus trees, available at California nurseries, grown in the ground and can be expected to get much taller – up to 25 feet, depending on variety. Be sure to provide more space in the ground for standard size trees. Generally, a Semi Dwarf tree needs an 8-10 foot diameter space, while a Standard tree should be provided with a larger growing space – up to 15 feet in diameter.


Climate
In general, ground-planted citrus trees are happiest in warm, temperate areas. Some varieties are much more frost-tolerant than others. For information on a specific variety, please refer to our hardiness table.



Location
A sunny, frost and wind-free location with southern exposure is best. If in doubt about the location, leave the tree in its plastic container and place it in the spot you have in mind. Water as needed, and after a week or two you should be able to tell whether or not it's happy.


Reflected heat from sidewalks, walls, driveways, or other structures can help to create a warmer "microclimate." Avoid planting citrus trees in lawns that get frequent, shallow sprinklings. Don't crowd your tree, for even though it is a Semi Dwarf, it will need room for its eight-ten foot ultimate diameter. The root system can reach far beyond the drip line.

Soil
Citrus trees are famous for tolerating a wide variety of soils, including clay. However, good drainage is essential, as citrus trees can't survive standing water for long. To test your drainage, dig a hole 30" deep where you would like to place the tree. Fill with water to saturate the soil. The next day refill it with water. Your drainage is OK if the water level drops 2" in two hours. If the water does not drain well, plant your tree in a raised bed and then amend the soil as described in the following paragraph.

Soils rich in humus are best. For heavy or poor soils, we recommend digging a large hole and filling it back in, half with the best of the original soil, and half with a good-quality amendment mix. Plant the root ball high to allow it room to settle over time. Crown roots should remain just below the soil line.

Planting
If the plant is growing in a container, gently invert the container to remove the soil intact. Trees that are somewhat dry will usually release more easily from the pot for transplanting. Squeezing the sides of a plastic pot can help to loosen the soil and roots. If planting a bare-rooted mail order tree, shake loose the shavings the roots are packed in before planting. Add the shavings along with your other amendments to the prepared mix for the planting hole.


Take note of the abundant fibrous root system. Straighten out any circling roots and cut off any broken or dead roots before planting. Amend your planting hole as described above. Do not add fertilizer to the soil while backfilling your hole; however, you can apply some to the soil surface after planting. Be sure to tamp soil lightly as you go and water thoroughly after planting to eliminate any large air pockets. Stake the tree as needed until well-established. Green plant tie is a good choice for tying trees to stakes.

Citrus trees are best planted during the active growing season. In summer it is best to plant in the early morning hours when temperatures are cool to moderate. Try to keep the roots out of the sun as much as possible. Water the tree thoroughly after transplanting. If desired, use a solution of Vitamin B-1 Rooting Tonic in the first few irrigations to help fine feeder roots recover more quickly. You may wish to pinch off fruit and blossoms for the first year or two after a new planting to encourage stronger root and branch development.

Watering
Consistency is the key with citrus watering! As with so many plants, citrus trees like soil that is moist but never soggy. How often to water will vary on the environment and depends on soil porosity, tree size, and temperature. Allowing the top of the soil to dry slightly is OK. A simple moisture meter, available at garden supply stores, can be used to determine moisture down to about a 9” depth. Generally, when the meter indicates root moisture level of about 50%, (center of dial) it is time to water. Always store your moisture meter dry between uses to keep it functioning properly

A wilted tree that perks up within 24 hours after watering indicates the roots got too dry. Adjust watering schedule accordingly. A tree with yellow or cupped leaves, or leaves that don't look perky after watering can indicate excessive watering and soggy roots. In that case, water less frequently.

In the ground, citrus prefer less frequent, deep watering to frequent, shallow sprinklings. Creating a watering basin around the drip-line of the tree can aid in deep watering. As the tree grows, be sure to expand the basin as needed to keep it as wide as the spread of the branches. Deeper watering promotes deeper root growth and strengthens your tree. Generally, once-a-week watering works well for in-ground plantings. Be sure to adjust based on weather conditions! In general, it is best to water in the morning, but if plants are dry or wilted it is better to water them immediately, rather than wait until morning. 


Mulches
Liberal use of mulches will conserve precious water and help inhibit weed growth. A 2-3 inch layer of redwood shavings, fir bark, compost, or other organic matter can be very helpful for water retention. To reflect heat and hasten fruit ripening, some people mulch with light colored gravel or crushed rock. “Living mulches” such as nitrogen fixing clovers can also be planted between trees in an orchard. To avoid root diseases, always keep grasses and other vegetation away from the root collar area. Keep all mulches at least six inches away from the base of the trunk.

Suckering
Know where the graft union is on your tree. It can usually be seen as a diagonal scar between 4 and 8 inches from the soil. Remove all shoot growth below the graft. These so-called "suckers" take vitality from the top of the tree (the fruiting wood). Especially on young trees, they are very vigorous. Remove suckers as soon as they are observed. 



Thorns
Juvenile fruiting wood will sometimes have thorns. This is a young plant's way of defending against grazing animals. As the tree matures, thorns will not appear as often. Prune off thorns if desired.

IN CONTAINERS

An excellent choice for growing citrus in any climate.

Citrus trees are especially suited for container growing as they can be kept at manageable sizes. Container growing allows gardeners to overcome poor soil conditions or limited space in a landscape. People enjoy their trees in decorative pots on a patio or apartment balcony. Many customers have cold winters and bring their citrus indoors during freezing weather. These tips can help you on the way to successful citrus growing in containers.


Selecting Planting Containers 
We recommend a 6-9" container for our entry trees and a 10-14" container for our premium trees. A variety of decorative plastic containers are available at reasonable prices. Clay pots and wooden containers are attractive but less mobile choices. When selecting a container, be sure there are sufficient drainage holes. Drilling extra holes is an easy way to improve drainage with wood or plastic. As the tree grows, increase the container size to a 16-20" diameter pot (the next pot size up). Do not start with a pot that is too large as it makes soil moisture levels harder to control with small trees.


Selecting a Location for Outdoor Containers


Provide 8 or more hours of direct sunlight per day. If less than 6 hours of natural full sun is provided, supplement with grow lights. Usually an unobstructed South or Southwest facing window is ideal. Sunny, wind free locations with southern exposure are the best. If in doubt, leave the tree in its plastic container and place it in the spot you have in mind. After a week or two, you should be able to tell whether or not it is thriving. Reflected heat from sidewalks or houses can also help to create a warmer microclimate. Avoid placing containerized citrus trees on or near lawns that get frequent, shallow watering. To reduce excessive heat on the roots, try nesting plain plastic nursery pots into slightly larger decorative pots. This can help roots stay cooler. Be sure the pot never sits in standing drainage water. 


Selecting a Soil Mix for Container Planting


We recommend using commercially available potting mixes. Some experts make their own mixes using wood shavings, sand, and compost. Using dirt (native soil from your yard) in a container is not advisable. We also advise against putting gravel or any other material on the bottom of the pot, as this negatively impacts drainage over time.


The perfect high porosity soil mix can be hard to find, but we have found rose garden soil mixes (formulated for outside use) work well. Soils that are too heavy can be amended with about 1/3 –1/2 the volume of 1" redwood shavings or cedar hamster bedding. Pine and spruce shavings tend to break down more quickly, so are not ideal. Try to select hardwood chips that will last longer. If necessary, moisten the mix to reduce dust and make it easier to handle.


Use a soil mix that is lightweight and drains well. If the mix contains a large proportion of dense, absorbent material, such as peat moss or worm castings, amend with 1/4-1/3 volume of 1" cedar or redwood shavings. Water in thoroughly, using Vitamin B-1 rooting tonic in the first few applications, if desired. Once the roots have settled, we prefer using slow release fertilizers applied to the soil surface, rather than mixing fertilizer into the soil or using plant stakes. This avoids any risk of burning the roots.


When shopping for the perfect citrus soil mix, please avoid those that contain chemical wetting agents or fertilizers. Soil mixes formulated for outdoor use are preferable to potting mixes for indoor plants, since the later often contain chemical wetting agents, causing tree roots to remain too wet after watering. You can start with a good rich organic soil and amend with about 1/3-1/2 volume shavings, perlite or coco fiber. Mixes for Cactus/Citrus have a lot of sand but can work. Use your judgment to amend as needed.


Planting in Containers


Once your soil mix is prepared, the container is selected and the tree's eventual location is known, you are ready to begin potting.


Place prepared soil mix in the bottom of your new container. Gently slide tree roots out of the old container, trimming off any dead roots and detangling any circling roots so that growth into the new pot will not be impeded. If planting a bare-rooted mail order tree, gently shake the shavings loose from the roots and mix them with the planting mix. Place the loosened root mass into the new container and gently fill with your fresh planting mix, packing down lightly to remove large air spaces from the root zone. The top of the roots should be just beneath the soil surface, and crown roots (root collar area) should show above the soil line. Make sure that soil or mulch is not pushed up against the trunk of the tree. Water deeply. Stake loosely with green tie if needed. It’s a good idea to repot every year or so, or when you see roots peeking through drainage holes.


 Watering in Containers


Consistency is the key with citrus watering. Citrus trees require soil that is moist but never soggy. Develop a watering schedule so the roots maintain even moisture, but are not waterlogged. Watering frequency will vary with soil porosity, tree size, and environmental factors. Generally, once or twice a week deep watering works well for container specimens. It is best to water in the morning, but if plants are dry or wilted it is better to water them right away than wait until morning. Elevate pots above standing drainage water.


 


Water before leaves show wilting, and when roots have reached about 50% dryness. Even if the top of the soil is dry, check the moisture level in the soil surrounding the roots before watering. A wilted tree that perks up within 24 hours after watering indicates the roots got too dry. Adjust the watering schedule accordingly. A tree with yellow or cupped leaves, or leaves that don't look perky after watering can indicate excessive watering and soggy roots. Give your tree water less often.



A moisture tester can be an excellent tool to help determine when roots are in need of a drink. Because most commercial moisture testers rely on an electrical conductivity method, however it is possible to get miss-readings due to high salinity or other conditions. An alternative method recently shared by a New England citrus enthusiast simply employs a plain wooden dowel about the diameter of a pencil. Sharpen it with a whittling method (sharp knife) or pencil sharpener. Then insert this into the pot at varying depths, shallow to deeper, determining moisture using your direct senses (feel, smell, etc.).
As the previous example of an alternative moisture tester shows, indoor citrus trees inspire innovation! There is no one “right” soil mix, except all the ones that now contain happy citrus trees. People over the years and in every state have experimented, using locally available materials and resources to develop methods that work for them.



If the adventure feels daunting you can start slowly with one of these three “easiest to grow” trees: Meyer lemon, Bearss lime, Trovita orange. 

As Houseplants

For those with adequate indoor growing conditions

Citrus trees can be grown easily indoors! Key elements for success are good light, adequate humidity indoors in the winter, well-drained potting soil, additional nutrients, and consistent watering. Take any one of those away and problems can develop. Supply these key elements as indicated below, and you'll be on your way to a beautiful tree! 
 
Light
Citrus require 8-12 hours of sunlight each day to be healthy and productive. A South or Southwest facing window with unobstructed light is generally ideal.  Citrus trees do not go dormant in winter and will tolerate slightly lower light conditions during this period of slower growth. 


If your growing space receives at least 5-6 hours of full direct sun per day, supplementing with full spectrum bulbs or fluorescent plant lights can help trees perform well.  IF, however, the space provides less than 5 hours per day of direct, full sun, more sophisticated grow light systems may be necessary.  If you live in an area with cold winters and hot summers, you might consider treating your citrus as an indoor/ outdoor plant.



Temperature
Citrus grow best between 55°F and 85°F.  They can usually tolerate temperatures down to 32 degrees for 2-3 hours. Some varieties are more cold hardy than others. Citrus can handle temperatures over 100 degrees as long as they are well watered.   



Soil
We have found that a light, well-drained commercial soil mix, such as Rose Garden Soil (formulated for outdoor use) can work well. Some experts make their own mixes using wood shavings, sand, and compost.


Using dirt (native soil from your yard) in a container is not advisable. We also advise against putting gravel or any other material on the bottom of the pot, as this negatively impacts drainage over time.


Soils that are too heavy can be amended with about 1/3 – 1/2 volume of 1" redwood shavings or cedar hamster bedding. Pine and spruce shavings tend to break down more quickly, so are not ideal.  Try to select hardwood chips that will last longer. If necessary, moisten the mix to reduce dust and make it easier to handle. 


Be sure to apply a good fertilizer as appropriate.
 
Water
Water as needed to keep soil moist, not soggy. Generally 1/4 - 1/2 gallon of water every 5-7 days indoors is adequate. Be sure the bottom of the pot is elevated above standing drainage water. A moisture tester can be an excellent tool to help determine when roots are in need of a drink.  Because most commercial moisture testers rely on an electrical conductivity method, however it is possible to get miss-readings due to high salinity or other conditions.  An alternative method recently shared by a New England citrus enthusiast simply employs a plain wooden dowel about the diameter of a pencil.  Sharpen it with a whittling method (sharp knife) or pencil sharpener.  Then insert this into the pot at varying depths, shallow to deeper, determining moisture using your direct senses (feel, smell, etc.). 


 
Humidity
In winter months, heated rooms may need additional humidity. Placing the pot on pebbles in a saucer will elevate the tree above the drainage area, and improve airflow and humidity for citrus.  Misting citrus foliage with a simple spray bottle is another way to help citrus cope with insufficient indoor humidity in winter.


Enjoy!
When you provide these essential elements of success for indoor growing, you'll enjoy a fragrant, ornamental, and delicious houseplant unlike any other!


Please see our Growing Citrus in Containers page to review more helpful tips for successful citrus growing.

In a Greenhouse/Solarium

Ideal environment for container growing

Most citrus can be grown and fruited in greenhouses or solariums. Simulate a subtropical environment by keeping temperatures between 55°-95°F, with some humidity.


Midsummer shading in a greenhouse may be necessary to hold temperatures below 100°F. Shade cloth may be helpful to reduce greenhouse temperatures when draped over the structure.


Conversely if winter conditions are excessively dark and the resources allow, consider supplementing with grow lights. If your growing space receives at least 5-6 hours of full direct sun per day, supplementing with full spectrum bulbs or fluorescent plant lights can help trees perform well. IF, however, the space provides less than 5 hours per day of direct, full sun, more sophisticated grow light systems may be necessary. ACF Greenhouses is a good online source for helpful information about grow light systems.


Further cultivation information and planting tips can be found on our container page.

Growing organically

Tips for growing & pest management

Citrus trees can thrive under organic production methods. The basic requirements of full sun, excellent drainage, plus protection from frost and wind, apply equally to organically grown trees. All Citrus trees are heavy feeders, and require a steady supply of nitrogen and trace elements throughout the growing season, whether grown in pots, or the ground.


Container Growing
An ideal organic container mix will contain a variety of soil ingredients. When mixed thoroughly together, the blend should be friable, rich and fast draining, yet moisture retentive.


Start by combining commercial organic soil with compost, sand and fir bark, or choose from materials in your local area to create a suitable growing medium. Cedar shavings (hamster bedding), Coco shell fiber, pumice, decomposed granite and other materials can be used to help improve the saturation quality of heavy potting mixes and soils. Compost and worm castings can also be used, but keep them to under 20% of the total mix, or it may become too heavy. Citrus do like a slightly acid growing medium, but adding too much sphagnum moss for this purpose can impede root drainage, so use sphagnum sparingly. Avoid commercial mixes that contain chemical wetting agents or chemical fertilizers. Moist, not wet roots make a happy tree.


A 2-3 year old bare-rooted organic tree from Four Winds Growers should be planted in a standard 5 gallon size nursery pot (12-14” diameter). Containers designed for nursery use typically have adequate drainage holes. If using a terra cotta or clay pot, be sure to drill extra holes to improve drainage, or nest the plain pot inside the decorative pot, being sure to elevate the pot above the drainage area. Putting gravel or any other material on the bottom of the container when potting up is unnecessary, and can impede drainage over time, leading to water-logged roots. Make sure that when finished planting, the tree’s crown roots show just above the soil line.


Planting in the Ground


It is best not to plant your citrus tree in a lawn since lawns will compete with the tree for nitrogen and water, and allopathic chemicals from grasses can impede citrus growth. In heavy clay soils it may be necessary to plant on a mound to assure good drainage.


Citrus trees are heavy feeders, and our experience has been that you need to fertilize your organic trees more often, because organic fertilizers are generally not as concentrated as conventional commercial fertilizers. Good organic granular fertilizers are available on line and at garden centers. [Two examples are Dr. Earth (Organic #9 for Fruit trees) and EB Stone (Organic Citrus and Fruit Tree Food).] You can also top dress with compost or use brew your own compost “teas” to supplement fertilization.


In addition to timely applications of slow release granular fertilizers it is a good idea to apply foliar sprays of fish emulsion and kelp on a weekly schedule throughout the active growing season. Young leaves that have not yet “hardened off” (are about half of mature leaf size) absorb foliar nitrogen and trace elements best.


See details on planting in the ground.


Aphid, Scale or Mite, Oh My!
Be sure to check your trees at least once a week for pests or other problems.
Indoors and out, you can use bi-monthly soap solution sprays, toothbrush scrubber tool in hand, to combat the arrival of unwelcome aphids, scales, mites and others. Stress caused by insufficient light , excessive dust, or over- or under- watering will predispose trees to pest attack.


Be sure that ants are excluded from your citrus growing area. An excellent product to help keep trees clean and free of pests is Organic Orange TKO. If a scale infestation has already begun, one can simply scrub them off of branches and twigs with a soft toothbrush and wash off with the solution mixed in a spray bottle. [http://tkoorange.com/ ].


Bringing Indoors for Winter Growing
If citrus trees must spend long winter months indoors it is best to provide a sunny window that provides the perfect “California-like” indoor climate. When bringing trees indoors after a summer in the sun, please remember to consult your moisture tester and make certain that at the time of transition, the roots are about 50% dry. If you make sure plants you intend to bring in for the winter are a bit on the ‘dry side of moist’ it will help them adjust better to the new indoor conditions. Water them as soon as they are situated in their new winter home. To increase indoor ambient humidity you can place trays of pebbles and water below trees or use a mist bottle. Remember, happy citrus roots are moist, but never soggy. If your indoor growing space does not provide at least 8 hours of full sun per day, fruiting and growth may be compromised.


There is a ‘learning curve’ with citriculture, especially if you are planning your mini orchard in pots that you will need to bring indoors in winter. If you take care to maximize sun exposure, carefully monitor soil moisture, fertilize regularly and watch for pests, your organic citrus growing experience will be successful.

Winter Cold Protection

Action steps for outdoor citrus

Citrus varieties have different cold tolerances. See the Citrus Variety Chart for specifics. Have an action plan in mind and the supplies you need on hand.


When temperatures are expected to go below the tolerance shown, action must be taken promptly to protect citrus trees and other cold sensitive plants.


Container trees are the easiest. Move them to a protected location where they will not freeze such as a porch, garage, or in the house.


For trees in the ground or for container trees you do not want to move, here are some other options:


For certain, water the trees well. When soil freezes, it pulls moisture from the roots, damaging them. A combination of two or more the three ideas below will give you more protection than just one option. Anti-transparent sprays such as Cloud Cover will give 4-6 degrees protection for up to a month. Frost Covers, come either as bonnets or sheets. Other fabrics or plastic can suffice but will have to be removed in the day time. Frost covers breathe and can stay on the trees for days without damage. Make sure the material reaches to the ground; secure it so it doesn’t blow off the tree. Christmas lights placed in the branches of the trees can provide heat to offset the cold air.