In the spring, classrooms within the Wild Rose School Division are often full of plants that the students have started. It is not unusual to see grass-forming Happy Hairys, beans, bedding-out-plants or tomatoes being carefully tended.
Next year, one lucky school will be taking horticulture one step further — they will have access to a garden tower.
A garden tower is vertical hydroponic system. It differs from horizontal systems where plant roots are contained in horizontal pipes — which have a constant flow of liquid circulating through them — in that the plants are held in an upright tube with the liquid running over the roots at 15-minute intervals. Plant roots then grow down the tower and into the weak fertilizer solution in the holding tank.
Plants in both systems are started from seed in a solid growing medium. In the case of the garden tower, rock wool blocks come as part of the starter kit. Commercial growers tend to use blocks of compressed coconut fibre.
Seeds are placed in the blocks and kept moist and warm in a mini-greenhouse until the seeds germinate. Once they have developed two true leaves, the plants are placed in a small plastic pot with mesh sides, then placed in a pocket in the tower.
Joanne, who is looking after the tower at division office, found the tower easy to assemble and plant. The hardest part for her was to get all the plants to germinate.
As a result, she experimented by adding small plants to the tower pockets. First, she painstakingly washed all the dirt from the roots before placing them in rock wool and into the tower pockets. If soil had been left on the roots, it would have broken loose and plugged up various hoses and tubes, stopping the water and nutrients from circulating. When adding plants in the tower, also check that they are not harbouring insects.
So far, the tower has required little care. A weak liquid fertilizer, called Mineral Blend, is measured and added to a large water jug that is then added to the holding tank at the bottom of the tower as needed. At present, the liquid solution needs to be added every week or so but that will increase as the plants grow and take in more liquids and nutrients.
Mineral Blend is the brand name of the fertilizer developed to go with the tower. It comes in two containers, both with a different level of pH. One container holds nitrogen and a few trace chemicals. The other contains phosphorous and potash, along with many trace chemicals. This is the plants’ only source of nutrients. The liquid is pumped from a bottom holding tank, up the inside of the tower to the top, where it then runs back down, wetting the rock wool and roots on the way down.
The tower has been in operation since the first of May. At present, the tower holds cucumbers and tomatoes that were grown from seed. The cucumbers are flowering and the tomatoes should bloom next week. Other plants were bought as small bedding-out plants. Strawberries, lettuce, beans and flowers are doing well. Staff have been eating the lettuce and have plans for the strawberries that are starting to produce fruit and runners.
Gord Atkinson, associative superintendent of learning services, is responsible for bringing this technology to the school division. He was introduced to the plant towers at a workshop put on by the Ever Active Student Council and purchased a kit knowing the product could be used across the curriculum. An extra benefit is that it encourages healthy lifestyles through gardening and healthy eating.
The basic garden tower kit comes with a tower that holds 20 plants, seeds, fertilizer, pH testing kit, rock wool, a mini greenhouse, a timer and water pump at a cost of $617 and freight.
Lights, a dolly to make the outfit movable, a cage to hold plants in and lights upright all cost extra but are necessary if the tower is to be used throughout the year. The total cost was around $1,500.
For more information on the plant tower, go to www.planttower.ca.
Linda Tomlinson is a horticulturalist who lives near Rocky Mountain House. She can be reached at firstname.lastname@example.org.