Mid-season fertilization is important for pecan production to ensure higher nut yield and quality. Pecan trees have peak nitrogen demand during the foliage growth stage in early spring and the kernel filling stage in late summer. The tree progressively sizes the shell, fills it with liquid endosperm, and deposits the kernel between these two peaks in summer. The nut yield, size, and kernel fill percentage at harvest are all directly impacted by the time and rate of mid-season fertilization application. Fertilizing in summer also protects the tree’s capacity to produce a harvest in the following year. Nitrogen (N), phosphorus (P), and potassium (K) are the primary nutrients for pecan production. Nitrogen drives nut sizing and kernel fill and must be applied throughout spring and summer. Phosphorus and potassium, however, are primarily broadcast in spring (March–April). Micronutrients like Magnesium, Zinc, Nickel, and Boron should be applied as foliar sprays in late spring or summer if deficiency symptoms appear. Alternative sources of plant nutrients such as chicken litter and crimson clover can often help with high fertilizer costs in pecan production.
1. Pecan Nut Development Stages in summer
Post-pollination and fertilization mark the beginning of summer in pecans. Nut growth begins in May, and the nuts reach their full size towards the end of July. Shell hardening begins after the fruit gains full size and is completed by mid-August. The nut sizing stage (May–June) and the kernel filling stage (August) are high-nitrogen and high-water-demand stages. Any nutrient shortfall during these stages results in permanent yield and quality loss that cannot be corrected later in the season. Pecan nut development stages in summer are illustrated in Figure 1.
2. Soil & Leaf Analysis — Making the Right Decision
UGA Extension recommends leaf tissue analysis for designing a precise fertilizer application plan for a commercial pecan orchard. Leaf samples should be collected only between July 7 – August 7 because the nutrient concentrations in leaves are the most stable for diagnostic purposes at this time. Collect samples from sun-exposed terminal shoots. Collect 100 pairs of leaflets from all sides of the tree. Avoid any leaflets damaged by insects or disease. Wait at least 2 weeks after a foliar spray before sampling. Soil testing can also guide the fertilizer application rates. Growers should consider utilizing a combined leaf tissue and soil analysis decision system to monitor and manage plant nutrients in their pecan orchards.
Table 1. Soil & Leaf Analysis Recommendations for Pecan Fertilizer Management
| TEST | TIMING | ACTION |
|---|---|---|
| Soil Analysis | Preferred once a year or as required | Adjust pH, K, P, Mg, Ca before season |
| Leaf Analysis | July 7 – August 7 only — stable diagnostic window | Confirm N, K, Zn, Ni levels; adjust late-season program |
3. Fertilizer Rates and Timing
UGA Extension recommends a total annual nitrogen rate of 75–125 lbs N per acre for mature, well-managed, irrigated bearing orchards. Nitrogen should be applied in split injections through the irrigation system, whenever possible, at a maximum of 25 lbs N per acre per injection. This rate should be raised by 25% in sandy soil, utilizing more frequent and smaller applications.
The rate and timing of nitrogen recommended for summer through fertigation system is presented below:
May
- Continue with the three injections that began in April on 10-day intervals through early May. Each injection must not exceed 25 lbs N per acre. Space evenly and do not batch applications together.
June
- Apply one injection in June, a maximum of 25 lbs N per acre. This is the most important nitrogen application of the entire season. It feeds the tree during peak nut sizing and the onset of the water stage. Do NOT apply if no crop is set on the tree; excess nitrogen will drive vegetative growth at the expense of next year’s flower buds.
August
- Apply one injection in late August, a maximum of 25 lbs. N per acre only if the tree is carrying a heavy crop.
In case of a broadcast application, the fertilizer must be directed towards the herbicide strip only, not the full orchard floor. The fertilizer rate of 75-125 lbs N per acre should be based on the width of the spread, which is the herbicide strip, not the total size of the orchard. Nitrogen fertilizer should be applied in two or three split doses – a basal dose (one-third to one-half) in spring (April) and the remaining in summer (July-August).
4. Alternative Fertilizer Sources
Chicken litter and crimson clover can be potential alternate sources of plant nutrients in pecan orchards. These alternate sources can help to offset soaring fertilizer costs while improving soil health.
- Poultry Litter
Apply 1 ton/acre broiler litter in February and 1 ton/acre in May. Only 60% of the nitrogen (36 lbs N/ton) is available for crop uptake during the season. Use broiler litter only. Avoid layer litter due to calcium/magnesium concerns.
- Crimson Clover
A well-established Crimson Clover stand can eliminate late-season synthetic N applications. Crimson clover is a cool-season legume that fixes atmospheric nitrogen. It establishes well for a few years and may need re-seeding every 3–5 years.
5. Micronutrients — Zinc, Nickel, Boron & Magnesium
While nitrogen drives summer crop development, other micronutrients are also essential during the summer months. Sandy Coastal Plain soils across southwest Georgia are naturally low in zinc. Even when the soil reserves are present, micronutrients are locked out of plant uptake at soil pH above 6.0. Summer foliar sprays act faster than soil applications and are often the most effective delivery method for micronutrients.
Table 2. Micronutrient Application Recommendations for Pecans in Summer.
| Micronutrients | Deficiency | Rate | Timing | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Zinc | Rosette — small, puckered leaflets and bunchy shoot tips | 1 qt per 100 gallons of water | Apply as soon as symptoms appear. Repeat if symptoms persist throughout summer | ||||||
| Nickel | Mouse ear — small, round, cupped leaflets at shoot tips. Common on newly planted trees | 1.5 qt per 100 gallons of water | Apply as soon as symptoms appear. May require multiple applications per season | ||||||
| Boron | Reduced fertilization, poor nut set and shuck adhesion problems at harvest | Apply to the label rate. | Most critical window: April – June foliar application | ||||||
| Magnesium | Characterized by interveinal chlorosis, which forms a “Christmas tree” pattern on the leaf | 5 lbs/100 gal | First leaf stage through July | ||||||
6. Mid-Season Fertilizer Application Quick Reference Guide
| MAY | One to two N injections in 10 days interval Max 25 lbs N/acre per injection Sandy soil: increase rates by 25% Apply foliar Zn and Ni if deficiency symptoms are visible |
|---|---|
| JUNE | One N injection — max 25 lbs N/acre Skip entirely if no crop is set on the tree Continue monitoring for deficiency symptoms Apply foliar Zn, Ni, and B as needed |
| JULY | No major nitrogen applications in July Collect samples for leaf tissue analysis: July 7 – August 7 |
| AUGUST | One injection only if heavy crop set Max 25 lbs N/acre Sandy soil: increase rates by 25% |
References
- UGA Pecan Team, 2026, Mature Pecan Tree Management
- UGA Pecan Team, 2026, Management of Young Pecan Trees
- Wells, L. & Harrison, K.A., 2017, Cultural Management of Commercial Pecan Orchard
- Wells, L., 2021, Pecan Fertilization
- Sawyer, A., 2022, Insect and Nutritional Update on Newly Planted Pecan Trees
- Wells, L., Sawyer, A. & Brock, J., 2023, Pecan Management