ʻUlu Trees: Frequently Asked Questions

ʻUlu thrives in temperatures between 70–90°F. Nighttime temperatures should not drop below 55°F. Optimal elevation for cultivation in Hawaiʻi is below 1,500 feet (‘ulu can grow higher than this but is not viable for commercial production). Trees grown above the recommended elevation often produce very small fruits, if any at all. ‘Ulu prefers fertile, well-drained soils with ample potassium (K).

Currently, there is no established variety that does better at higher or lower elevations. Growers in higher altitudes are encouraged to consider planting varieties other than ma’afala, as this variety can produce fruits on the smaller side. 

Everyone has their own preferences, but the traits and qualities of various ‘ulu varieties are explored here; currently, the co-op is selling Hawaiian, Ma’opo, and Otea varieties. Growing multiple varieties can provide staggered harvest times and more resilience to pests and diseases, but it’s okay to plant based on preference or availability!

No, though more common with young ma’afala trees, not all ma‘afala fruit that we receive is rated as B-grade – we have several farmers with 100% A-grade deliveries. A-grade fruit needs to be 5 inches horizontally or vertically to fulfill this threshold. Ma’afala average fruit size is 5.5 inches & proper fertilization & maintenance will improve mature fruit grading.

ʻUlu trees grow best in areas receiving 60–157 inches of rainfall annually. While they tolerate dry periods, prolonged drought can lead to fruit abortion. Supplemental irrigation is recommended in drier areas, especially during the establishment phase.

ʻUlu is adaptable and grows in sandy coastal soils, sandy clay loam, and young lava rock. The optimal pH range is 5.0–6.5, though trees can survive in a wider range. Well-drained soil is essential to prevent root rot.

Yes, but trees may fruit later and require more intensive management. Adding compost, irrigation, and mulch helps improve success on marginal sites.

Dig a hole at least twice the size of the root ball. Water the hole before planting to reduce transplant shock. If standing water persists, improve drainage by adding cinder.

If soil tests indicate deficiency, incorporate compost, biochar, lime, gypsum, and chicken manure—outside of the root ball—to encourage roots to reach for nutrients. Backfilling the hole with native soil will help avoid drainage mis-match. Planting in larger mounds above grade can be helpful in poorly draining or very rocky soils.

Yes! Mulch heavily with grass clippings, leaves, or branches to conserve moisture, reduce weeds, and support soil biology. Cycling cover crops is a good way to cycle nutrients & provide soil cover.

Organic growers use compost, seaweed, and KNF inputs like Fish Amino Acids for fertilizers. ½ cup 6-6-5 per inch trunk diameter broadcast beneath the dripline seasonally should be adequate for young tree establishment, adjustable for soil test results.

A tree yielding 300 lbs/year needs about 22 lbs of NPK fertilizer (10-5-25) or 37 lbs of Bioflora (6-6-5) plus 13.7 lbs of K-Mag. Apply in 2–4 doses across the year, increasing frequency in wetter areas.

Standard spacing is 30×30 ft for commercial orchards. Tighter spacing (25×25 ft) allows for windbreaks or hedges but may reduce yield per tree. Row orientation should allow for adequate light penetration to reach inside the orchard, otherwise shaded trees will produce less fruit.

Every 1–2 years. Prune vertical leaders to encourage lateral branching and better fruit set. Keep trees below 18 ft for easier harvest. More comprehensive pruning resources here.