Citrus (Citrus Genus)

If you live in California, especially in any of the numerous valleys, chances are good you have a citrus tree. If you don’t, probably a neighbor does. If you are Greek, you for sure do (and if you don’t, what the heck???).

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*A handy growing summary chart is at the end of the article.*

In fact, the popularity of citrus trees like lemon, lime, orange, grapefruit, kumquat, etc., poses a bit of an agricultural conundrum. So many people have them that there are actually far more citrus trees being grown in residential neighborhoods than there are in commercial orchards. The issue isn’t about competition, but rather the spread of pests and disease. But more on that later.

The reason for the popularity of growing citrus should be pretty obvious. The fruits are delicious, healthy, come in a variety of flavors, and make great additions to recipes both savory and sweet. The evergreen trees are attractive, make abundant displays of pretty and beautifully scented flowers when in bloom, come in a variety of sizes to suit any garden space, are prolific fruit producers without needing to be thinned, and are relatively easy to grow. The most unique feature is that most of the fruits are ready to harvest in winter, long after all the other darlings of summer fruit harvests have faded into memory.

Pick a flavor, any flavor.

In my garden I have seven different citrus trees. Yes, that’s a bit more than the average person. There are two oranges, two lemons, and one each of kumquat, lime, and mandarin. Each is different enough in flavor that there really isn’t much overlap, especially when using them for cooking and baking. Here’s a breakdown of what each has to offer:

• Eureka Lemon: this is what most people would envision when thinking of lemons. Pure yellow inside and out, acidic lemon flavor, but with thicker skin and larger size than the typical lemon at the grocery store. The varieties usually sold in the grocery store are Lisbon, which is similar to Eureka flavor-wise, but the Lisbon is smaller and has thinner skins than Eureka. From my experience, Lisbon trees are more vigorous but a little unruly, while the Eureka is a little more fussy, but stays better in check and the thorns are not so wicked.
• Meyer Lemon: I actually have a variety called “Improved Meyer Lemon” which has more disease resistance than the original Meyer to certain viruses. The fruit is the same on both. What makes the Meyer distinctly different from other lemons is that it is actually a hybrid with an orange variety in its lineage. The fruit shows it, too, with a hint of orange color in the juice and thin skin, and also a slightly sweet flavor. The tree is also little smaller in stature. You can use this anywhere you would use lemon, but be aware of that sweeter flavor. It’s perfect for use in desserts as a result.

• Blood Orange: these are rather unique citrus in color and taste. As the name implies, these oranges have a hint of red to them, both inside and out. They are not as sweet as typical oranges, but this works well if you are looking for something to add contrast. Many people describe them as having a bit of raspberry flavor. Despite their more tart flavor, they work well in any sweet recipe and add a nice zing to beverages like Sangria. I love them in my spinach salad.

• Washington Naval Orange: when you think of oranges grown in California, this is what you are thinking of. They are delightfully sweet, seedless (due to the fact that they are sterile and produce no pollen), and have easy peeling skins. Valencia oranges, on the other hand, are the type better adapted to Florida’s climate and are the “juicing oranges”, due to their high juice content. I had a Valencia tree in the past and prefer the Naval for both eating and juicing, as Valencia is a bit more tart, though this is actually a better attribute for making marmalade. The Naval orange is a more fussy tree, but worth the effort for the versatility. Both varieties grow large unless you select a dwarf type.

• Mandarin: sometimes also referred to as Mandarin orange, but these are distinctly different from the other orange varieties out there, though they are believed to be the ancestor of all oranges. Mandarins have thin skins that peel easily, but aren’t the best for zesting, and the fruits are flattened on the bottom. They can also be very seedy if there is the opportunity for cross-pollination with other citrus. However, they are very juicy and delightfully sweet. These are really more of an eat “as-is” fruit, though they could be juiced and the segments could be canned in syrup for preserving. Clementine is a seedless variety, but is still a type of Mandarin. Tangerines are simply a variety of Mandarin, as are Satsumas.

• Persian Lime: these are your typical grocery store limes. Tart lime flavor, thin skin, lots of juice, and few seeds. They would be comparable in use to the Eureka or Lisbon lemon, whereas Key Limes would be more akin to Meyer lemons. Despite their more tart taste, Persian limes are still perfectly suitable to use in both sweet and savory dishes. Fun fact, limes will ripen to a yellow color and look very much like lemons. If allowed to stay on the tree to this point, the juice will also be a little less intense in flavor and tartness.

• Kumquat: I’ve long ago lost the tag that identifies which variety of kumquat I have, but based on what little memory still remains and on information from the internet, I’m pretty sure it’s a Fukushu. This variety is actually believed to be a chance hybrid of Mandarin orange and another kumquat. The skin is thinner and the fruit is larger than that of other kumquats. In general, kumquats are very tart, but are great for candying and adding to other sweet recipes. The variety I have is also unique in that it is the peel that is sweet, while the juice is tart!

How to grow them.

• Light: Though citrus can tolerate some shade, especially in hot and dry climates, they really prefer full sun. If you’re stuck planting in an area that is shaded, make sure it is morning or afternoon shade and not both, and certainly not all day even if it is light shade.
• Soil: Citrus are greedy because they are such prolific producers. They need a lot of help especially in poor soils. There are fertilizer blends specifically made for citrus and organic options do exist. One suggestion for timing when to supplement the soil is to use Memorial Day, 4th of July, and Labor Day as your dates for even spacing. That would be the end of May, beginning of July, and beginning of September for those of you outside the USA. For those of you in the southern hemisphere, just add six months to each for your summer schedule.

• Water: They like this, too, as do most subtropical plants. However, if your soil is dense clay, be sure to be mindful of oversaturating the soil as this will lead to root rot. For overly sandy soil that drains too fast and heavy clay soils that drain too slow, you may want to amend your soil with organic material that will help retain water appropriately while also helping to feed it.
• Temperature: Citrus don’t mind the heat if properly supported with water, but they are not cold tolerant. Most varieties will start to die off at temperatures below 30 F. If you flirt with those temperatures but don’t have serious freezes, you can protect your citrus by using incandescent Christmas type lights (not LED, they don’t generate enough heat), covering with plastic, and/or watering the tree (the water actually acts as a heat sink helping to warm the area slightly. Thankfully, there are many varieties of citrus that will grow well in large pots for those of you in colder environments that have room indoors to keep them. Just be sure to provide a very sunny window and keep on top of soil moisture as they will dry out more quickly.
• Pollination: Bees are clearly your friend here, and if you have citrus you will likely have bees coming to visit. However, it helps if you have other bee friendly plants in your yard to encourage them to visit. If you are growing your trees indoors, you will need to pollinate by hand. Use a clean paintbrush to gently brush inside the flowers once they have opened to help distribute pollen.

What went wrong???

Unfortunately, a lot of things can cause problems for citrus, especially if you live in an area where diseases and pests can easily travel due to the number of nearby trees. Some things are easily remedied, are normal, or indicate that you need to completely remove your tree.

• Nutrient Deficiencies: These will often show up as discolored leaves, often with yellowing in distinct patterns (e.g. along the veins or margins). Leaf drop may also occur. Check that your tree is receiving adequate water so it can absorb nutrients from the soil. Don’t go crazy and over fertilize, though. An imbalance in soil nutrients can also cause problems due to the chemical interaction of some of the minerals in the soil.
• Pests & Disease: Sadly, there are so so so many. Often pests will show themselves through the physical damage they do, primarily in the leaves. Leaf miners will leave tunnels in the undersides of leaves under the cuticle. They are mostly harmless, especially to healthy, established trees. Other pests are not so nice as they are spreaders of disease. The Asian citrus psyllid spreads citrus greening disease, a fatal and contagious disease. There are no treatments for this and the tree must be destroyed to prevent spread. This website from the esteemed University of California is a good place for information on problems you may encounter in your citrus.

• Sudden Fruit Drop: This is normal, to some extent. As I mentioned earlier, citrus are prolific producers of fruit. The tree usually can’t support all the fruits that it sets, and so it sheds the extras. There is no need to thin them as citrus are really good at doing it on their own. However, sometimes sudden and excessive high temperatures and/or periods of drought can cause the tree to drop more than usual. You can help reduce this by ensuring the tree is properly watered during heat waves, and providing some shade for those that are exposed to full sun. Properly supported trees won’t be as susceptible to this problem.

Time to reap the rewards!

Citrus is typically ready to harvest during the winter months, though some smaller varieties like kumquat may have fruit year round. The fruits are ready to harvest when they are fully colored and are easy to remove from the stem. One of the neat things about citrus is that you don’t have to worry about harvesting them all at once. You can leave them on the tree as long as you want and harvest as needed (this is usually the Old Man’s favorite part!). The only time you need to worry about the quality of the fruit is if temperatures drop to or below freezing. Freezing, especially before the fruit is ready, will negatively affect the quality because the little capsules that hold the juice will often burst open as the water inside expands. Protecting the tree during cold spells with the strategies mentioned above will help protect and extend your harvest.

So what now?

Aside from just eating them, citrus fruits feature in so many delicious dishes both sweet and savory. Click on the following words for recipes that use these various fruits! Lemon Orange Kumquat Lime

Plant Summary:

• Perennial: Plants will live for several decades
• Evergreen: leaves will remain all year
• Height: depends on variety, dwarfs in pots can be up to 8 feet, dwarf in ground 8 to 12 feet, standard up to 25 feet
• Width: depends on variety, generally not as wide as they are tall
• Sun: full sun, can tolerate some morning or afternoon shade in hot areas
• Water: regularly, do not let soil get dry
• Soil pH: neutral to slightly acidic
• Soil type: amend heavy clay or loose sandy soil
• Key nutrients: best to use fertilizer balanced for growing citrus
• Planting time: best to plant in fall through spring
• Zones: outdoors 9-11, colder zones will need to bring indoors