How to reduce labor in greenhouse vegetable production

Labor is usually the greatest expense item in the production of greenhouse vegetable crops.

During the past few years, considerable equipment has been developed that can aid in making normal hand tasks less labor intensive.

Examples include motorized lifts, stringing and hook winding machines, vertical sprayers, deleafers, harvesting trolleys, tomato sorting machines and robot harvesters.

The following is a short review of some of these machines, most of which have been developed in Europe and China.

Scissor lifts

High-wire production has become the standard in tomato, cucumber and pepper production. Maintenance, such as suckering, clipping, wrapping, leaf removal, pinching and harvesting, of these crops is best done from a motorized scissor lift that raises the worker to a convenient height. Lifts can either be rubber-tired for use on a walkway or mounted on pipe rails at the base of the plants. Most are powered by 24-volt electric motors with controls at operator level. The lifts are designed to fit narrow row spacing and are available with work heights to about 20 feet.

Transport trolley

Designed for moving harvested fruit from the growing to the packing area, these can be manufactured to fit different rail spacing and carton size. This machine has push handles, brakes and rubber swivel center wheels to move on concrete walkways.

Stringing machines

Crops such as tomatoes are usually supported by string attached from an overhead support wire to the base of the plant. An automatic stringing machine can cut the string to a predetermined length at a rate of up to 1,500 per hour. Mounted on the scissor lift, the grower can attach the string to the support wire as the trolley travels along the growing bed.

Vine crop hook winding machine

Formed wire hooks are used to allow adjustment of the plant support twine. They usually hold 30 to 50 feet of twine and are reusable by adding new twine. Wrapping the twine on the hooks is a repetitive task and very time-consuming. Hook winding machines are available that can wrap up to six hooks at one time at a rate of about 250 per hour.

Tomato plant deleafing robot

Removing the lower leaves of tomato plants reduces the incidence of disease and allows more light to reach the fruit. Deleafing is a slow, tedious task. A recently developed robot from French engineers at Aisprid detects the leaf to be removed and cuts it off with precision. The leaf is dropped in the aisle to be collected later, and the knife is sterilized. The machine is self-contained and operates on pipe rails.

Leaf vacuum

A leaf vacuum is a handy complement to the above robot. Designed for leaf and debris pickup around pipe rail systems, it operates with two motors: an electric motor for machine movement and a gasoline engine to power the fan that picks up and chops the leaves, which are collected in a hopper.

Bio Chopper

When it is time replant a crop, the old crop is gathered and placed on a transport mat in the aisle. This carries the dead plants to a Bio Chopper at the end of the aisle. After shredding, the residue can be collected in a bin or conveyed directly to a trailer. The transport mat is rolled for reuse.

Vertical boom chemical sprayer

A sprayer with single or double vertical booms is needed to get good coverage of spray material to tall crops. These machines are available as either pipe rail-mounted with separate transport wheels or rubber tire-mounted for flat aisle surfaces. 

Options include a hose reel model with material supplied from a central tank or a trolley model with chemical tank and high-pressure pump. Units are available that will apply several spray materials in one pass.

Tomato harvesting machines

Using artificial intelligence and cameras to detect and harvest fruit, these machines usually require a pipe rail system for movement. Some can move automatically from one aisle to the next. Efficient handling methods are needed to move the fruit from the growing area to the packing area.

Tomato grading machines

These computer-controlled machines are designed with four functions: in-feeding which gently dumps the fruit from the picking box or bin; grading, which uses cameras to examine for internal quality, texture, taste and defects: sorting, which determines fruit weight, maturity, firmness and sugar content; and packing, which conveys fruit to packing stations for boxing and palletizing.

This article appeared in the April 2025 issue of Greenhouse Management magazine under the headline "Striving for efficiency."