Soil-less substrates in pots or bags can be replaced year to year, eliminating the need for crop rotation and fumigation. This system is often used in conjunction with greenhouse or tunnel systems for environmental protection, and the crop can be placed at any height for more ergonomic and effective labor usage. Additionally, most of the structural and irrigation components of these systems can be reused for multiple years (10-15+), reducing the long-term cost and environmental impacts.
Two of the most used soil-less substrate components worldwide for strawberry production are coco fiber and peat-based mixes. Substrates such as bark, wood fibers, Canadian peat moss, and perlite are readily available and presently in common use in other industries, such as the ornamental nursery industry. Little information is available to assist strawberry growers in making appropriate substrate selections for their operation. We evaluated the performance of greenhouse grown strawberries (Fragaria x ananassa cv. Albion) in six substrate blends sourced from different soil-less material with the goal of assessing strawberry production in local source substrate material in comparison to the grower standards (coco coir and European block peat) for the Southeastern US.
Soil-less substrate mixes that were investigated in this study
Performance of the strawberry 'Albion' was investigated in six custom mixed soil-less substrates for two growing scenarios: A Spring planting ('Experiment 1') and a Fall planting ('Experiment 2'). Following soil-less substrates were used:
- (CF) 100% Coco Coir (=grower standard)
- (PP) 50% Canadian Peat / 50% Perlite
- (PC) 50% Canadian Peat / 50% Coco coir;
- (PW) 50% Canadian Peat / 50% Wood Fiber (locally source pine);
- (PB) 50% Canadian Peat / 50% Bark (locally source pine);
- (EP) European Peat mix (BVB)
Premier professional grate Canadian peat moss was used for the 50/50 mixes. Coco Coir was washed and buffered. Perlite was horticultural grade perlite. Substrate raw materials were measured out by cubic feet volume and mixed together manually to create the 50/50 blends. Pulverized dolomitic limestone was added to PB, PW, PC and PP when mixing to bring substrate pH up to ~5.6 before starting the trial. Lime was incorporated into the substrates, uniformly mixed, left to sit overnight, and mixed again before being used. Sixteen 1.64 feet (=0.5 meters) long pots were filled with each substrate and checked by weight to make sure all were equivalent. Containers were filled level to the top of the container without compressing the substrate (Figure 1).
University of Georgia
Planting material and planting dates
Strawberry (Fragaria x ananassa cv. Albion) mother plants or tips were received from Norton Creek Farms, Waynesville, NC. Mother plants were rooted in an indoor nursery at the farm. Daughter plants were then harvested when needed and rooted directly in 21 cell trays (~240 cc cell volume = tray plant) under a separate misting greenhouse at the farm. For Experiment 1, rooted tray plants were planted on 3/14/21. Plants were removed on 6/23/21 with a growing duration of 102 days. For Experiment 2, tray plants were planted on 9/27/21 and plants were removed on 6/12/22 for a growing duration of 259 days (Figure 2).
University of Georgia
Greenhouse and Experimental Design
Each experiment contained the same substrate treatments (see list above). Each treatment was replicated four times in space in a randomized complete block design. Each experiment had a total of 24 experimental units, with 16 plants per unit. Each unit consisted of four half-meter containers (Bato Plastics), filled with the designated soil-less substrate (Figure 2) and four plants per container.
The trial was conducted inside of a commercial mid-tech multibay plastic covered greenhouse facility in Zebulon, NC. Each greenhouse bay measured 100 feet (30.5 meters) long by 21 feet (6.4 meters) wide. The gutter height of the structure was 8 feet (2.45 meters) (Figure 3).
University of Georgia
Gutters
Gutters were developed and custom built by the lead author. This system included an elevated growing platform for more ergonomic crop care and harvest activities. Sixteen-inch-wide sections were cut from expanded metal fencing panels and bent into U shape Gutters. Rebar brackets held the gutters on top of two ~4' tall posts which had been driven into the ground. To allow for the capture of drainage water from each individual unit, rows were split into 8-foot sections and installed on a ~2% slope. Twenty-inch-wide strips of white plastic were cut out of white greenhouse film (6 mm thickness, AT Films) and fastened over top of the gutter with the edges overlapping slightly. A modified stapler was then used to staple the plastic around the gutter frame to secure it into place (Figure 3).
Read more at smallfruits.org