How-to: Hydroponic vining crops basics

In its on-site research greenhouse, CropKing produces tomatoes for about 10 to 11 months, and lettuce and leafy greens year-round. Greenhouse growers typically grow indeterminate tomato varieties, which keep producing nodes, so they always are producing additional inflorescences or flower clusters, said CropKing horticulturist Matthew Kispert.

Tomatoes, cucumbers and peppers make up most greenhouse vining crops, said CropKing. For these crops, the company offers a bato bucket growing system, also known as Dutch buckets. Growers typically fill these buckets with perlite and populate each bucket with two plants. The bato buckets sit on top of a 1.5” drain line to capture excess runoff from the growing area. The Dutch buckets feature a small reservoir allowing the plants to always have access to nutrient solution. CropKing drip-irrigates these crops on a scheduled timer or accumulated light.

CropKing recommends seeding in rockwool for vining crops. Ideally, growers should germinate tomatoes in media with a temperature between 80 and 82 degrees Fahrenheit. The crops flourish in similar temperatures after transplanting into the buckets.

As with temperature, maintaining the relative humidity of vining crops is important. The ideal range for relative humidity is between 58 to 80 percent. Paying attention to both your temperature and your humidity is important — growers can't only pay attention to temperature and ignore humidity.

Vining crops require regular pruning and trellising. To maintain upward growth, growers need to pinch off suckers, which they should do by hand. Using a utensil could contaminate the wound and initiate or spread an infection. With cucumbers, growers should remove tendrils to prevent the plant from wrapping onto others. While CropKing uses a lean-and-lower method for tomatoes, it flips its cucumbers over the support wire and terminates the crop after they reach the plant base.  Due to the shorter crop cycle for cucumbers compared to tomatoes you can get 3-4 crops of cucumbers through a bucket in the same time it takes to complete a growing cycle for a tomato plant.

Tomatoes require pollination to set fruit. Growers typically use bumblebees to pollinate in a greenhouse because they are about 85 percent effective, while a pollinating wand is about 80 percent effective. Alternatively, growers can shake the support wires with a broomstick, which is about 70 percent effective, Kispert said. Greenhouse cucumbers, meanwhile, don’t require pollination or have seeds.