Liquid Fertilizers for Avocados

Fertilizing Avocados

• Nitrogen is the nutrient avocado trees are most likely to need; they may also need potassium when they start producing fruit. Avocados benefit from monthly applications of fertilizer from early spring through fall, because of their shallow root systems. According to University of California Cooperative Extension, small but regular applications of nitrogen allow you to use less fertilizer — whether organic or inorganic. But make sure soil pH is at least somewhat acidic before starting any fertilizer program — before planting, if possible — because any soil pH greater than 7 stops the uptake of micronutrients including iron and zinc.

Liquid Avocado Fertilizers

• Backyard and commercial trees that are allowed to develop a deep mulch of their own leaves may eventually need little fertilizer; as mulch decomposes, it supplies a steady stream of nutrients. Add some composted horse manure to boost the nutritional quality of mulch. But until mulch can do the job — after at least 10 years of leaf accumulation — easiest to use are liquid fertilizers including fish emulsion, urea, ammonium sulfate and potassium sulfate, as well as water-soluble commercial organic and inorganic fertilizers with nitrogen-phosphorous-potassium percentages suitable for avocados.

Fertigation With Drip Systems

• “Chemigation” is the term for injecting chemicals into plant irrigation systems, and the process is known as “fertigation” when those chemicals are fertilizers. There are many benefits, according to University of California Cooperative Extension. If the irrigation system can deliver fertilizers uniformly, then distribution is greatly improved, along with flexible application timing. Reduced labor and fertilizer use also help lower costs. Dry fertilizers and organic fertilizers can be applied through fertigation, but they first must be dissolved in water or otherwise made soluble.

Other Liquid Fertilizer Applications

• Fertigation is effective for applying nitrogen and other nutrients to avocados, but many commercial and backyard growers make a larger initial fertilizer application in early spring. Applying liquid fertilizers, organic or inorganic, directly to the soil is fine for this. Foliar applications of nutrients and micronutrients — spraying leaves, for direct cellular absorption — allow you to immediately supply what’s needed when deficiency symptoms are noticed.