when to fertilize citrus trees in arizona: AZ Complete Guide

When to fertilize citrus trees in Arizona? We’ll tell you exactly when, and with what, to get those citrus trees growing and producing fruits. Arizona has a long growing season, perfect for citrus trees.

AZ isn’t without its challenges, though. The intense summer heat can be a bit too much for these trees, especially the younger ones that are still establishing themselves.

It’s not just the heat; the naturally alkaline soil in the area can make it harder for the trees to access some essential nutrients. This means growers sometimes have to step in, adding what the soil lacks to keep their trees happy and healthy.

Water is another big concern. Arizona is dry, and citrus trees need a regular supply of water to thrive. With the region’s water supply challenges, ensuring the trees get enough can be a task in itself.

Mulching is your friend in AZ. Mulch helps the water stay longer, work harder, and keeps the scorching sun from burning the soil. Another integral part of is understanding when to fertilize citrus trees in Arizona.

So, let’s dive deeper into the science of feeding your citrus trees!

When to Fertilize Citrus Trees in Arizona

Citrus trees are a hungry bunch. They need steady nutrients to grow well and give us those juicy fruits we love. By feeding them right with the right fertilizers, we’re not just keeping them strong and healthy; we’re also making sure the fruit tastes just perfect—with that sweet and tangy kick.

The Best Months to Fertilize in AZ

Spring (February to April)

As spring rolls around between February and April, those citrus trees are ready to burst with growth. With the days getting longer and the warmth setting in, it’s a good time to boost them with some high nitrogen fertilizer. This helps promote leafy growth and gets the tree ready to flower.

An N-P-K (Nitrogen-Phosphorus-Potassium) ratio with a higher first number would be ideal. Something like a 10-6-6 or 12-4-4 would work well. The higher nitrogen content encourages that lush, green growth that’s so important for the tree’s health and productivity in the spring months.

Summer (June to August)

Even with Arizona’s strong summer sun, citrus trees keep on growing. Using a balanced fertilizer during these months supports this growth and makes sure the young fruits get the nutrients they need.

During these months, it’s a good idea to use a balanced fertilizer, something close to a 1:1:1 NPK ratio. This means equal amounts of nitrogen (N), phosphorus (P), and potassium (K). This combination ensures that the trees not only grow well but that the young fruits get the nutrients they need to develop properly.

Fall (September to October)

As winter approaches and the trees get ready to take a break, they need some extra nutrients to beef up their roots. Using a fertilizer with a good amount of potassium in it can give the roots a boost and keep the whole tree strong and ready for the next growing season.

At this time, picking a fertilizer with a higher potassium content can make a difference. A good NPK ratio is something like 0-10-10 or 5-15-30, where potassium (the last number) is the standout. This boost in potassium will reinforce the tree’s roots and help it stay healthy as it transitions into the cooler months.

Don’t Fertilize In Winter

As the cool air settles in, citrus trees in Arizona take a bit of a breather. Their growth slows down, and they don’t need as much food. So, during these winter months, it’s a good idea to give the fertilizing a break. This gives trees a chance to use the nutrients they’ve soaked up during the year without getting overwhelmed.

Plus, over-fertilizing during this period can lead to new growth that might be damaged by cooler temperatures. Let them have their winter rest, and they’ll be ready to spring back to life when the warmer days return.

There are other things you can do for your citrus trees in winter:

• Water. While citrus trees need less water in winter than in the heat of summer, it’s still important to keep a consistent watering schedule. Arizona’s winter can be dry, so make sure the soil around the tree doesn’t become completely parched. Deep water every few weeks, allowing water to reach the deeper roots.
• Protect from frost. Although many parts of Arizona have mild winters, there can be occasional frosty nights, especially in the desert areas. Young citrus trees, in particular, are vulnerable to frost damage. You can protect your citrus on those expected cold nights by covering them with burlap or frost cloth. Remember to remove the cover during the day.
• Prune. Winter is a good time for light pruning if needed, as it’s easier to see the tree’s structure without its dense foliage. Remove any dead or diseased branches, but don’t go overboard. Excessive pruning can expose the tree to cold damage.
• Mulch. Adding a layer of organic mulch around the base of the tree (but not touching the trunk) can help retain soil moisture and provide some insulation against cold temperatures.

Don’t miss: Our deliciously easy papaya juice recipe!

Chlorosis (Yellow Leaves) In Arizona’s Citrus Trees

If you’ve got a citrus tree in Arizona and you’ve noticed its leaves turning yellow, you’re not alone. This condition, especially when the leaf veins remain green against the yellow of the leaf, is known as chlorosis.

It’s basically the plant’s way of telling you it’s missing some essential nutrients. Let’s dive deeper into the three most common deficiencies that cause this and how to address them.

Iron Deficiency

• Symptoms: Young leaves turn pale yellow, but the veins remain green. As the deficiency gets worse, the entire leaf might turn a whitish-yellow and the edges could appear burnt.
• Solutions: The problem here is not always the absence of iron in the soil but its unavailability due to high soil pH. So, while you can add more iron, it’s essential to ensure it’s in a form the plant can use. Conduct a soil test if chlorosis is a persistent problem!
  • Chelated Iron: This is a form of iron that’s easier for plants to absorb, especially in alkaline soils, which are common in parts of Arizona.
  • Iron Sulfate: Another option is to apply iron sulfate, which can also help to acidify the soil slightly, making it easier for the tree to absorb the iron.

Zinc Deficiency

• Symptoms: Leaves become smaller and there’s space between the leaf veins which turns yellow. Over time, branches may die back and there’s poor fruit set.
• Solutions: Zinc deficiencies are also common in high pH soils.
  • Zinc Sulfate Spray: Applying a foliar spray of zinc sulfate is a quick fix as the leaves absorb it directly. It’s best to do this in cooler months or early morning to avoid leaf burn.
  • Soil Application: Incorporate zinc sulfate into the soil to address the issue from the roots up. Remember to water well afterwards.

Magnesium Deficiency

• Symptoms: The edges of older leaves turn reddish-purple or brown and curl upwards. The area between the veins may turn yellow.
• Solutions: Magnesium deficiency is less about soil pH and more about the amount of available magnesium.
  • Epsom Salts: A popular and easy fix is Epsom salts. Simply dissolve them in water and water your citrus tree with the solution. Epsom salts provide a direct source of magnesium that the tree can quickly use. If you have Gardenia plants, this is often a fix for their yellow leaves, too!
  • Magnesium Sulfate: If you want to go a step further, you can use magnesium sulfate, which is a more concentrated form and can be mixed with the soil.

Always remember to test your soil before any major treatments to make sure you’re addressing the real issue. Many nutrient deficiencies are caused by soil pH rather than an actual lack of nutrients.

You can save yourself a lot of money by conducting a soil test!

Final Fertilizing Tips

Water

Always water the tree thoroughly before and after applying fertilizer. Pre-moistened soil ensures even distribution of nutrients and helps prevent root burn.

Application

Apply the fertilizer in a ring around the tree’s drip line. A tree’s drip line is an imaginary line on the ground that corresponds to the outermost circumference of a tree’s canopy.

Picture it like this: If it rains and the raindrops fall from the outermost leaves and branches of the tree, where they hit the ground would be along the drip line. Most of a tree’s absorbing roots (those that take up water and nutrients) are located at or beyond the drip line.

When you water or fertilize a tree, it’s essential to target the area around and just beyond the drip line since that’s where the critical absorbing roots are most concentrated.

Fertilizing around the drip line maximizes nutrient absorption!

Mulch and Cover Crops

I can’t mention mulch enough. In an orchard, mulch is your best friend. Go crazy with the mulch! Combine mulch with cover crops for the perfect partnership.

Cover crops improve your soil and act as living mulch. Legumes, such as clover and alfalfa, are top choices for citrus growers in Arizona. They fix nitrogen from the air into the soil, reducing the need for additional nitrogen fertilizers.

Buckwheat is another fantastic option, as it not only grows quickly, providing rapid ground cover, but also attracts beneficial insects and pollinators with its flowers.

Lastly, you can sow ryegrass in the cooler months. It helps prevent soil erosion, suppresses weed growth, and, when you till it back into the soil, adds valuable organic matter.

These cover crops not only protect and improve the soil but they also contribute to a thriving ecosystem around your citrus trees. The better the ecosystem, the more your trees’ll thrive.

I could go on and on about growing fruit trees, but since this article is meant to be about when to fertilize citrus trees in Arizona, and not ‘the complete guide to growing fruit trees’ – I’d better leave it here.

See ya next time AZ!