If you’re growing citrus in Arizona, knowing when to fertilize citrus trees in Arizona is your key to success. The desert climate creates unique challenges, and getting the timing right makes all the difference for a healthy, productive tree.
This guide gives you the simple schedule and tips you need. We’ll cover the best times of year, what fertilizer to use, and how to apply it properly for optimal growth.
When To Fertilize Citrus Trees In Arizona
The general rule for Arizona citrus is to fertilize three times a year. This aligns with the main growth flushes of the tree. Missing these windows can lead to weak growth and poor fruit production.
Here is the recommended feeding schedule:
- Late February to Early March: This first application supports the major spring bloom and fruit set. It’s the most important feeding of the year.
- Late April to Early May: This feeding sustains the developing fruit and supports the summer growth flush.
- Late August to Early September: The final feeding helps the fruit mature and prepares the tree for the coming winter. Never fertilize after October, as it can promote tender new growth that will be damaged by frost.
Why This Arizona Schedule Works
Citrus trees in Arizona have a longer growing season than in cooler climates. Our warm springs and falls mean the tree is active for more months. Fertilizing on this three-time schedule provides a steady supply of nutrients exactly when the tree needs them most.
Fertilizing in winter is a common mistake. The tree is semi-dormant and can’t use the nutrients, which can then wash away or even harm the roots. Sticking to the spring-summer-fall plan is much more effective.
Signs Your Tree Needs Fertilizer
Even with a schedule, your tree might show you it needs a little extra. Look for these clues:
- Pale green or yellowing leaves, especially on new growth.
- Leaves that are smaller than usual.
- Very little new growth during a growing season.
- Reduced fruit production or fruit that drops prematurely.
Choosing the Right Fertilizer for Arizona Citrus
Not all plant food is created equal. Citrus trees have specific needs. In Arizona, our alkaline soils also affect what we should use.
Key Nutrients to Look For
A good citrus fertilizer will have nitrogen (N), phosphorus (P), and potassium (K). Nitrogen is the most critical for leaf and branch growth. Look for a ratio where the first number (Nitrogen) is highest.
A formula like 20-10-10 or 16-8-8 is often recommended. Many Arizona gardeners have great success with a specialized “citrus and fruit tree” fertilizer, as it’s formulated for these exact needs.
The Importance of Micronutrients
Our desert soil is often lacking in iron, zinc, and manganese. These micronutrients are essential for preventing yellow leaves. Choose a fertilizer that includes these, often listed as “chelated” micronutrients. This means they are in a form the tree can absorb easily in our high-pH soil.
You can also apply these separately if you see signs of deficiency, like yellow leaves with green veins. A foliar spray can provide a quick fix.
How to Apply Fertilizer Correctly
How you feed your tree is just as important as when and what. Proper application gets the nutrients to the roots where they’re needed.
Step-by-Step Application Guide
- Measure: Determine how much fertilizer to use. A common guideline is 1 cup of granular fertilizer per year of the tree’s age, up to a max of 6-8 cups for a mature tree. Always check the label on your specific product for exact rates.
- Water First: Always water the soil deeply a day before you fertilize. Applying fertilizer to dry soil can burn the delicate feeder roots.
- Spread Evenly: Sprinkle the measured fertilizer on the soil surface starting about a foot from the trunk and going all the way out to the “drip line” (the edge of the canopy) and a little beyond. The feeder roots are out here, not right at the trunk.
- Water Deeply Again: After applying, water the area thoroughly. This helps dissolve the fertilizer and carries it down into the root zone.
Special Considerations for Potted Citrus
Citrus in containers need a slightly different approach. They use up nutrients in the limited soil more quickly. You may need to fertilize a little more frequently, but with smaller amounts.
Use a balanced, water-soluble fertilizer every 4-6 weeks during the growing season (March through September). Make sure your pot has excellent drainage to prevent salt buildup from the fertilizer, which can damage the roots.
Common Fertilizing Mistakes to Avoid
A few simple errors can set your tree back. Here’s what to steer clear of:
- Over-fertilizing: More is not better. It can burn roots, cause excessive leafy growth instead of fruit, and pollute groundwater.
- Fertilizing at the Trunk: This can damage the bark and doesn’t feed the roots that need it.
- Ignoring Soil Health: Fertilizer isn’t food; it’s more like vitamins. Good soil structure is vital. Adding compost once a year improves soil and helps it hold nutrients.
- Forgetting to Water Deeply: Shallow watering after fertilizing leaves the nutrients in the wrong place. Deep watering is essential in our arid climate.
Integrating with Your Watering Schedule
In Arizona, deep watering is non-negotiable. A well-watered tree can actually use the fertilizer you provide. During the hot summer months, your tree will need water much more often.
A good practice is to check soil moisture a few inches down. If it’s dry, it’s time to water. Consistent moisture, especially during flowering and fruit development, leads to the best harvest.
FAQ: Fertilizing Citrus in Arizona
Can I use organic fertilizer on my citrus tree?
Absolutely. Organic options like well-composted manure, blood meal, or commercial organic citrus blends work well. They release nutrients slower, so they may need to be applied a bit earlier in the season to be available when the tree needs them. They also improve soil health over time.
Is it okay to fertilize my lemon tree in the summer?
Yes, but timing is key. The second feeding in late April/May covers early summer. Avoid fertilizing during the peak extreme heat of June and July, as the tree can be stressed. The late August feeding is perfect for late summer/early fall growth.
What if my citrus leaves are turning yellow?
Yellow leaves can have a couple causes. If the veins stay green while the leaf yellows, it’s likely an iron deficiency common in our alkaline soil. Try a chelated iron supplement. If the whole leaf is pale or yellowing, it could be a general nitrogen deficiency or overwatering. Check your fertilizing schedule and soil drainage.
How much fertilizer does a mature orange tree need?
A mature, full-sized citrus tree (over 5 years old) typically needs about 6 to 8 cups of granular fertilizer per year, split across the three annual applications. Always start with the lower amount and observe your tree’s response. The label on your fertilizer bag is the best final guide.
Following this Arizona-specific schedule will give your citrus trees the best foundation. They’ll reward you with lush growth, fragrant blooms, and a bountiful harvest of fruit for you to enjoy. Remember, consistency is more important than perfection—mark your calendar for those three yearly feedings and your trees will thrive.