Extend Your Cucumber Harvest with High Tunnel Growing

By Blake Jackson

High tunnels provide an excellent environment for producing high-quality cucumbers, particularly as field harvests taper off. By using trellises, growers can extend the season and maintain yields, though the window for replanting in midsummer is fairly short. With careful planning, however, it is manageable.

One of the main differences between tunnel-grown and field cucumbers is the choice of variety. Growers should select parthenocarpic types, which set fruit without pollination. Popular options include Corinto and Lisboa.

These cucumbers must be shielded from pollinators, as pollination often leads to misshapen fruit. Simple window screening on tunnel sides and vents helps exclude pollinators while also blocking cucumber beetles, though smaller pests like thrips, mites, and aphids can still enter.

For those who planted cucumbers in spring, harvests usually decline by late June, just as field production begins lowering prices. This makes midsummer an ideal time to clear out old vines and establish a second crop. By seeding between mid-July and August 1, growers can expect harvests by early to mid-September.

Most varieties begin fruiting around 45 days after the first true leaf and continue producing for another 45-60 days. Early planting within this window is crucial, as reduced daylight in October slows growth unless supplemental lighting is used.

Managing pests and diseases in fall is often more challenging than in spring. Powdery mildew is common during humid summer months, so a preventative fungicide program should begin at emergence.

Downy mildew, which travels north on storms each year, requires close monitoring and immediate treatment at the first signs. Later in the season, gray mold (Botrytis) can become a problem under cool, damp conditions; good ventilation and peroxide-based products help reduce risk.

Soilborne diseases are also a concern when planting after a previous crop. A peroxide drench followed by microbial inoculants can lower inoculum levels.

Meanwhile, spider mites, aphids, thrips, and cucumber beetles are consistent threats in tunnels. Regular scouting, proactive treatments, and rotating insecticide modes of action are essential.

With timely planting, smart variety selection, and vigilant pest control, high tunnels can deliver a productive and profitable late-season cucumber crop.

Photo Credit: gettyimages-diane-labombarbe