Labour savers

In the march towards ever greater efficiencies growers are, of course, looking to automate their operations as much as possible.

Nowhere is this more apparent than in the glasshouse sector, which has always been the leader in the horticulture industry for introducing technological innovations. Glasshouses, producing such things as young plants, pot plants, salads and cut flowers, provide an ideal environment in which growers can exercise increasing control over conditions, inputs and the various stages through which plants must progress to reach a saleable state.

In this last area, ambitious UK growers have made sizeable investments in recent years. Among the most important reasons for this are concerns over labour costs and availability. Famous examples of these growers include Roundstone, Westland, Donaldsons, Coletta & Tyson, Double H, Tangmere,and Madestein, among others.

Plant propagator Hillgate Nurseries, of Kings Lynn, Norfolk, is another, and serves as a good example of why digging into the pockets to make the huge investments needed to keep ahead of the game in the sector makes good economic sense.

Hillgate’s managing director David Barton told Commercial Grower his nursery produces around 180 million upwards of young salad and brassica plants - consisting of such things as lettuce, endive, Chinese cabbage, celery and others.

His system, based around de-stacking mechanisation, was introduced three years ago and installed by Dutch company Flier. It set Hillgate back more than £600,000.

“There is a big saving on labour costs,” said Barton. “What used to take 10 men all day to do now takes two men five hours. It’s easily cut labour needs in half. And, of course, it helps tackle the problem growers have in finding labour in the first place. There just aren’t enough people who want to do the job. There’s also a lot more hassle involved with workers - people not turning up for work, being off sick, that sort of thing.”

Flier estimates that, in the case of Hillgate, initial investment should be made back over a period of five years. Even so, Barton is firmly of the opinion such investment is essential: “We wouldn’t really be able to compete without the new technology. As far as the plant propagation industry is concerned, if you don’t mechanise you can’t compete.”

But he does not relish handing over money in such large sums on a regular basis. Neither does he see the necessity: “I wouldn’t think the system we have will be superseded in the foreseeable future. There’s not much improvement that can be found. The system was not cheap and I would expect it to last another 10-15 years before I even thought about changing it.”

But that has not stopped Hillgate planning another 1.5 acres of glass, to be put up by Cambridge HOK, in the near future.

West Sussex-based young plant propagator Madestein’s boss Peter Zwinkels echoes David Barton’s opinion that the major driver for mechanisation is to cut labour costs. He says it is no coincidence the major innovators for this technology come from The Netherlands.

He says: “In Holland labour costs are even higher, which is one reason the country leads in this sort of investment. Holland also has lower interest rates, which makes it easier for growers to invest. And it manages better returns for money spent.

“The Dutch industry is also in a better geographical position to exploit the European market and the banking system is more pro-horticulture.”

He also agrees with Hillgate’s md that he does not detect too many technological advances on what already exists on the horizon. “I can’t see many new big steps forward,” he said.

Neil Stevenson, of Double H Nurseries, Hampshire, is committed to technology to drive his business forward. The company installed automation back in 1995 and updated that in 2005. Another programme of development is being undertaken this year.

The mobile table systems handle pot plants, watering and packing. Stevenson says labour is one of the issues behind the use of mechanisation. Other issues are an improved use of space in the glasshouse, flexibility of cropping, increased speed, better responsiveness, improved quality of the product and a reduction in waste.

“Typically, for major projects, we look for a return on our investment in something like seven years,” he says.

“Without the systems you are going to be left behind. Certainly for the core crops.”

Double H is putting up more glass this year. The 17,000 square metre block should be in commission around October this year. It is designed for growing orchids which the company sees as a niche crop with a big future. It produces about 5,000/week at the moment but that will be increased to 12,500 once the new glass is up and running.

product focus

The number of automated systems on the market are many and varied and details can be found on the websites of the different companies. Below is a run down of just a few of the things on offer from three of the leading companies in the sector.

HAWE Systems Europe BV’s container system allows the plants to be placed on mobile carriers which carry them to the work station. Hawe says the containers are manageable, easy to stack and durable. Container frames can be built in the company’s factory or on location. Container sizes can be agreed with Hawe.

Container bases can be made in various materials:

Metal netting.

Expanded metal, made out of aluminium or sunk steel.

Styropor, Styropor plate.

Plastic, high impact resistant, suitable for ebb/flow culture.

Aluminium, bottom is integrated in the container frame. Suitable for ebb/flow culture.

Container roller conveyor & tubular rail track

The container roller conveyor transports containers between and within the different greenhouse departments and processing areas. In the longitudinal direction the containers are moved from one tubular rail track to another. Crop handling operations can be done along container conveyors.

Depending on the degree of the automation, tubular rail tracks and container conveyors can be provided with container conveyor drives, container stops, ejectors and haulways. The drives ensure the transport of the containers over container conveyors in the longitudinal direction. A container conveyor stop is used to stop the container in the correct place, so that he can be ejected by the ejector. An ejector is an electrically driven unit for ejecting a container from the container track segment on the tubular rail track.

Overhead crane

This overhead crane, also referred to as hanging stacker/destacker, makes an important contribution to the optimisation of the container movements in the handling room. Stacking and/or unstacking empty containers (in two or four directions) is carried out independently.

With an overhead crane empty containers picked by the potting robot are stacked or brought to the washing system. The washed containers can be stacked again (buffered) and put back on a feed conveyor to a set-down robot.

HAWE Systems Europe BV’s also has a mobile gutter systems for cut flowers. All systems are custom made.

Hawe gives examples of systems in place. Holstein Flowers built a new nursery of 58,000 sq m in De Lier. The nursery has 21 sections and each section is provided with moving gutters, which circulate in their own section. Each gutter has an approximate length of 4,500mm. In each section there are two rows and each row has 431 gutters. The total area of a section is 2,690 sq m.

H C van Os & Zn has built, on their existing location in De Lier, a 23,000 sq m new nursery. HAWE has installed in their glasshouse a new automated moving gutter system for cut roses. The nursery has been built up in seven sections, with each section equipped with moving gutters, which circulate in their own section. In each section are two rows with 241 moving gutters in each row. Centre to centre distance is 550 mm and the total measurement of a section is 3,180 sq metres.

Pot robot

The pot robot is electrically controlled and used to place plant pots automatically in containers. It ensures that a set number of pot rows is automatically moved on the container. A robot can have a pick-up and set-down function.

A set-down robot puts the pots in the containers, after they are filled or when the pots have been removed from the containers. A pick-robot ensures that the pots are picked up from the container, so that the plants can be put wider or go to the delivery belt.

Along with many other products in the filling, seeding, vision grading, pot handling, packaging, washing and internal transport, Visser’s potting machine Beta 16 and 32 is used for filling pots of different sizes with soil. The central adjustable pot carousel is provided with a potting ring for 16 or 32 pots and can be adjusted by means of a crank. The pot size can vary from 8-24 cm (Beta16) and 8-13 cm (Beta32).

The potting speed can be adjusted by means of a frequency control. The capacity is approximately 800-7,000 pots/hour (depending on the pot size to be processed and the type of pot).

The potting machine comes complete with a special drive worm to rotate the carousel, which enables it to be driven without bumping. The drill unit has its own drive motor and can turn right and left for drilling in and out the soil. The height of the carousel is adjustable.

It also comes complete with a pot dispenser. The height of the pot dispenser is adjustable for different pot sizes and can process pots up to 24cm.

The potting machine is highly compatible with other automation and processing systems. Systems that can be placed next to the potting machine are, for instance, transplanting systems: Type PC 11, Type PC 14.

Product specifications:

Minimum pot size: 80 mm.

Maximum pot size: 240 mm.

Maximum capacity: 800 - 7.000 pots per hour, depending on pot size and pot type.

Visser’s Pic-O-Mat PC-12 automatic transplanting machine is used for planting in trays, packs and larger pots. It is equipped with six or 10 transplanting grippers, which have servomotors for flexibility.

Programming of the different planting programs can be done on site by the operator. Several settings can be changed while the machine is in operation, such as picking height of the grippers, planting height of the grippers and the speed of the machine.

There is a maximum of 50 plug trays and 50 pots that can be stored in the memory of the computer and with a maximum of 100 combinations. And there is an option to plant different colours or species in a pack or basket.

Grippers are suitable to pick up a wide variety of plants and in a big range of plug sizes.

There is a capacity of up to 16,000 plants/hour, depending on the number of grippers used, plug size, pot size, plant height, travel height of the gripper, plant species, root development and number of plants per pot.

Among Flier’s offerings are a linear robot that is freely programmable in its movements, because both axles are controlled separately. The normal capacity of the robots is 400 actions/hour.

Depending on the plant size and the position the capacity of the linear robot is a maximum of 600 actions/hour.

The standard robot is delivered with a fixed fork, consisting of an aluminium plate with chambers for the pots. This fork can be interchanged easily. Also it is possible to use grippers in the robot, which actually grip the pots. This is preferable if plants have been grown with each other. These robots can be used for picking up pots or replacing, or both functions together.

Flier also offers grading capabilities which allow for consistency in product quality. The grading systems developed by Flier use cameras, which are controlled by specialists of Aris BV in Eindhoven.

A report is made for each plant. Hence the grower knows that the customer’s specifications are being precisely met. Height and thickness measurement have been possible for a long time already, as has grading on colour. Flier claims its system can also count the number of flowers ready for sale. At the same time the flowering phase of the plant can be determined.

The plant sizes determine the supply and discharge of the plants to and from the camera position. The plants are optimally viewed by turning them when they are passing the camera. In this way the plant is viewed at all sides at high speed.