Propagation tray basics [advertorial]

2018 Ask the Experts - 2018 Ask the Experts: Trays

Proptek’s Paul Greenley discusses the company’s propagation tray designs, their impact on plant quality and their environmental impact.

November 27, 2018

Paul Greenley
Photo courtesy of Proptek

Produce Grower: What are root training ribs and why are they important for vegetables?

Paul Greenley: We took our patented root training technology from the tree and shrub pots we make and built these into our vegetable trays. This means that roots grow down and are forced to the drainage hole, rather than circling and choking up. It’s a simple thing that really improves plant quality — you get the roots right and the bits above the soil have a good chance of being great, too.

PG: A lot of Proptek trays claim to increase the number of plants per tray over Styrofoam equivalents – doesn’t this reduce plant quality?

PG: Proptek’s vegetable trays do not require a large outer rim, which means that it is possible to fit in more cells per tray. Styrofoam trays have large outer rims and thick cell walls due to the nature of the material that they are made from, while thermoformed trays require the rim to stop them from bending and to add rigidity. As Proptek trays do not require a rim we are able to produce them with more cells per tray, but we are also able to space them out enough to ensure that plant quality is not compromised.

PG: Injection molded trays are much more expensive than throwaway trays like Styrofoam or thinner plastic models. How quickly, if at all, can growers make their money back from such a big purchase?

PG: Injection molded trays are tougher, heavier and have more plastic in them — so they are a bit more expensive. In terms of getting money back, that’s quite a complex answer as it depends on crops, size of nursery and how many seedings you do a year. However, we have found people’s ROI can be less than a year — but we typically say two to five years to be on the safe side. This extra money comes from three places: not having to buy any trays in subsequent years, more plants surviving to be sold and that the trays are easier to work with. It takes fewer people less time to fill, seed, move and then pull the plants from the trays, helping cut down labor costs.

PG: What are the environmental impacts of an injection molded tray? Is using plastic really a good thing?

PG: It is! Proptek trays are made from reprocessed material. Then once the tray is worn out, it can often be reprocessed yet again. It is plastic — but when you look at the awful waste (and expense) that something like throwing away Styrofoam produces, it is much, much better.

Injection molded trays are much easier to clean — they just need a quick tap and then a steam for a couple of hours. This sterilizes them with no expensive and potentially harmful chemicals. As the trays are tough, this heat and steam doesn’t damage them like with Styrofoam or thermoformed trays.