Pots and containers

Superior propagation products can justify extra expenditure by providing precise cell fill, optimum root development and healthy plugs, writes Sally Drury.

PG Horticulture: specifications for all types of growing and air pruning - image: PG Horticulture
PG Horticulture: specifications for all types of growing and air pruning - image: PG Horticulture

Propagation is the starting point for many plant producers. Along with seeds or cutting material, growing media and fertilisers, one of first decisions to be taken will be on the propagation tray or module. But should you just opt for the cheapest? After all, they are all the same, and minimum spend will result in a saving and perhaps even a bigger profit, right?

It is a common view that money can be saved by buying inexpensive trays for propagation, germination and growing - "any old tray will do". But perhaps it is better to consider the tray as a life-support system for the plant given that the objective is to produce the best plants possible with minimum waste. Good tray design and selection should ensure correct cell fill, superior root development and a healthy plug that can be easily removed from the tray. These benefits can easily outweigh the initial cost of the tray.

Correct matching

"Whether you are growing tomatoes, ornamentals, strawberries or trees, it is important to correctly match the plant and its growing requirements to the properties offered by the tray," says PG Horticulture business development manager James Avery.

PG Horticulture, with its German partner HerkuPlast Kubern, is a leading manufacturer of high-quality, long-life and also single-use trays. It has extensive experience in tray design, offering specifications for any growing situation.

It is essential to consider the specification and match it to your needs. Several factors must be taken into account. The right tray is a key factor in determining the quality of the end result. Gone are the days when a professional grower was simply handed the choice of single-use or reusable trays. Other factors needing consideration include environmental conditions, the type of substrate used, rooting requirements, cell volume, drainage and air pruning. It may seem clear that a tomato plant, for instance, requires a different cell compared with that needed by a tree seedling.

Avery explains: "Growers should ask whether their crop is lightor heavy-rooting. For a light-rooting crop, less volume is needed and a conical cell would be appropriate. For heavier-rooting crops, more cell volume is necessary to provide roots with the space they need. Root ribs may be required for tree seedlings, the channels guiding the roots and ensuring they develop in a preferred direction rather than spiralling."

Offset stacking is another inspired feature, allowing trays to be stacked for transportation or storage but without "blocking" or preventing the plant from growing.

"Whatever the crop, during the germination or propagation stage, good root development and spread is vital throughout the entire plug. This ensures optimum use of the substrate and improved uptake of water," Avery points out.

Additional features such as drainage holes are important and can play a far bigger role than water management alone. "Air pruning is key to healthy root development," adds Avery. "When trays are raised from the ground, even slightly, air movement improves and air pruning will occur, leading to a healthier root system. Plugs can then be more easily removed from the tray."

Air pruning can be achieved either by using trays with specially designed legs or by using air pruning racks specifically designed to hold multiple trays off the ground. Plugs can be removed from trays using cell-specific popper boards.

Choosing your trays

But let's go back to the first question - single-use or reusable? "If trays remain on-site or are returnable, then washing and disinfection make a lot of sense," says Avery. "HerkuPlast has two brands of tray - QuickPot, which is a fully reusable option, and HerkuPak, offering single-use with potential reuse capability of a twoto three-year life."

QuickPot trays are manufactured using heavy-duty reusable polystyrene. According to Avery, given a little care there is no reason why these trays will not last 10 years or more, making the overall cost per plant exceptionally low. "The cost of a lightweight tray will initially be much lower than a QuickPot tray, but QuickPot can be a highly competitive alternative to single-use trays, even after accounting for washing and disinfecting," he says.

The HerkuPak tray is made from a thinner material and has a 20mm rim around the edge to make the tray easier to handle. Both the QuickPot and HerkuPak are suited to automation and are available in Danish, Euro and Standard sizes, in addition to Paper Pot trays for all types of plugs.

Aware of environmental footprints, HerkuPlast uses high-quality recycled materials in the manufacture of its products. Its factory and warehousing roofs are equipped with solar panelling to deliver the energy needed for tray manufacture. CO2 emissions are reduced by 70 per cent and end-of-life trays can be washed, ground and reused to make recycled film.

QuickSearch app

To enable growers to find the trays they need, HerkuPlast has introduced a QuickSearch app. The company's database of propagation trays has been growing rapidly over the years and now includes 150 models in different qualities, resulting in at least 450 options.

"The app asks for some simple specification details, such as dimensions, cell volume, durability and number of plants per square metre, in order to search the database and reduce the options to a handful," explains HerkuPlast sales director Alfred Boot. "The app then shows the models that will fit your requirements and this information can be emailed to you." The new tool is for iOS and Android and can be accessed via HerkuPlast's website.

Growers that like to produce plugs in convenient-to-move-on paper pots should note that Modiform has teamed up with Sungro of Denmark to offer a new 100 per cent biodegradable product. The new paper, for use with paper-pot machines, is completely free of fossil oils and can be formed into a pot without the use of glue, but the special feature is that the pot will disappear in the soil with no residue.

More paper pots are available from Green Products of Kampen in the Netherlands. The company uses a cigar machine to fill the pots with growing media to meet specific requirements, the most popular size being 13mm but sizes down to 8mm can also be achieved.

Latest pots and containers to hit the market

Made from recycled water bottles and available in degradable and non-degradable versions, Root Pouch is a fabric container with lifting handles that helps create a dense, healthy, fibrous root system without spiralling. Containers are available in a variety of colours and in sizes from 3.8 to 2,271 litres. The degradable containers are offered with different expected lifespans, from 12-15 months to four-to-five years.

With open sides and flat construction, Poppelmann TEKU's PT2556-12F/8 marketing tray is designed to get decorated coverpots noticed.

Eco-Expert 100 per cent recycled/recyclable and biodegradable packing from Modiform is manufactured from moulded paper/cardboard pulp and offered in plant pots, carry trays and transport trays.

The upgraded Jiffypot R2 from Jiffy has the advantage of staying dry even when exposed to water or humid substrate. Maintaining its rigid form and clean surface, it is 100 per cent biodegradable but offers "degradable durability".

Focusing on lightweight packaging and using recycled materials, Soparco is developing thin-walled pots and thermoformed product lines using plastics made of 85 per cent or more recycled waste.

Available in transparent plastic or a variety of colours, the KalaMitica is a magnetic orchid pot from Key Essentials.

A display planter that fits on railings and the water-conserving London hanging basket are new products from JFH Horticultural Supplies.

Entering the vertical gardening market, The Pot Company has introduced stackable wall pots available in either cement or terracotta colours.

Winning designs

Universal Bedding Packs from Modiform took the professional products award at the Four Oaks Trade Show in September. The redesigned version of an old classic allows 20 trays on a single trolley shelf instead of the usual 18. It also means 5,000 more packs per acre - 30,000 more plants when six-packs are used - increasing production capacity as well as reducing transport costs. Made of a new plastics material, the trays are more robust but still priced in the "budget" range. Available with four, six, nine or 12 cells.

A new vertical growing system from exclusive importer Lows of Dundee won overall best new product award at Glee last month. SkALE comprises a fish-scale pattern of planting pods. Offset positioning gives plants such as herbs and flowers room to grow while the patented CASkADE system allows water to move down and fan out through the wall. SkALE is available in commercial quantities and a retail pack for garden centres. Lows' international buyer Dave Wrigley and horticultural director Rosie Wrigley received the award.


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