How watermelons grow

From greenhouse transplants to field harvest — the lifecycle behind every Hermiston melon.

Plant biology

Watermelon (Citrullus lanatus) is a warm-season cucurbit — related to cucumbers and squash. It needs frost-free days, full sun, and consistent moisture during fruit set and sizing. Vines spread widely; commercial plantings use spacing and sometimes plastic mulch to warm soil and control weeds.

Planting in the Columbia Basin

Hermiston-area growers typically plant after spring frost risk passes, often using transplants for uniform stands. Sandy soils warm quickly — an advantage in Eastern Oregon. Drip or furrow irrigation from Columbia River system water delivers precise moisture in a region that receives limited rainfall during summer.

Why Hermiston conditions excel

Temperature swing: 90°F+ days and 50s–60s°F nights during ripening boost sugar retention
Sandy loam: Good drainage reduces root disease; easier harvest in dry fields
Solar radiation: Long summer days at higher latitude extend photosynthesis hours
Experience: Multi-generational growers optimize planting dates for July harvest windows

Pollination and fruit set

Seeded varieties require bee pollination. Seedless melons are grown alongside seeded pollenizer rows. Poor pollination causes misshapen or hollow fruit — commercial operators manage hive placement carefully.

Harvest

Melons are hand-cut when tendrils dry and rind ground spots turn yellow. Hermiston harvest crews work quickly in heat — fruit moves to shaded packing lines and refrigerated trucks for Northwest distribution. Peak labor hits mid-July when temperatures climb into the 90s and 100s.