5 Tips for Building Strong Roots

Here are five tips for determining which containers are best for your operation.

1. Consider pots that allow for aeration.

When Matt Spitzer, founding partner of Triangle Hemp in Raleigh, N.C., moved into hemp from hydroponic produce, he found girdling roots on seedlings and transplants.

Looking to traditional horticulture, Spitzer discovered the natural air-pruning response that happens when roots hit air instead of solid walls: Roots stop outward growth—as though they’re pruned—and intensify dense, fibrous, lateral growth.

Aeration pots, which allow roots to contact air, capitalize on this reaction. Optimizing healthy root growth was key to early success for Spitzer.

2. Investigate paper pots.

Paper container options transcend pulp pots and corrugated trays. Daniel Ortega, head grower at Denver-based ornamental grower Botany Lane Greenhouse, propagated with environmentally friendly paper pots for years. When Botany explored hemp, the permeable air-pruning pots were a natural propagation choice.

Ortega explains that hemp roots, though vigorous, aren’t as strong as ornamental crops. With plastic plug trays, hemp roots pulled loose at transplanting suffered shock. Paper pots alleviated transplanting problems.

3. Explore fabric growing containers.

Fabric pots have flooded the market in recent years, but there are suppliers of the fabric container technologies that date back more than 30 years.

These time-tested aeration pots are well known in ornamental tree production, but the pots gained fans among cannabis and hemp growers shifting to year-round controlled-environment production indoors and in greenhouses.

The consistency and purity of permeable fabric designed specifically for air pruning to maximize root mass and nutrient uptake are strong draws. With mother plants, the increased root mass generates greater and faster vegetative growth.

4. Consider plastic aeration options.

Post-propagation, Ortega worried about root problems that plague container plants during cool, damp Colorado winters. After reaching out to his supplier of paper propagation products, he settled on two-part pots that combine a grid-like insert with a stabilizing outer holder that elevates plants off the ground.

The pots represent years of university and industry research to optimize plastic-to-air ratios and maximize aeration benefits.

Ortega says the design discourages root disease and its spread. “It’s almost like every plant is on its own little island. If one is struggling, it’s one plant. Everything else is going to be fine,” he says. Plus, his plants rooted to the edge or bottom in half the time, with an increased mass of feeder roots.

5. Invest in your roots.

For growers exploring container options, Ortega advises keeping the plant’s root system foremost in mind. “In cannabis and hemp, a lot of investment goes to lights. A lot of investment goes to humidity and temperature control,” he says. “This is investing in your root system. If a plant has a good root system, it’s going to be able to handle a lot of variables.”

Editor’s Note: A version of this article was originally published in September 2020 and has been updated from its original version.

Jolene Hansen is a freelance writer specializing in the horticulture, cannabis and CEA industries. Reach her at jolene@jolenehansen.com.