2019 ASHS Annual Conference

Hydrogels polymers to improve substrate water retention and increasing in popularity. The effectiveness of these hydrogels are influenced by substrate properties as well as fertilizers in the substrate. The aim of this research was to quantify substrate water retention and plant growth as impacted by the addition of two different hydrogels. Hydrangea macrophylla ‘Everlasting Revolution’ liners were planted in 7.6 L containers filled with one of four substrate combinations: 75% peat/25% perlite, 50% peat/50%perlite, 75% coir/25% perlite, or 50% coir/50A% perlite. Peat containing substrates had lime incorporated. There were three soil additive treatments: a control with no additive, Terra Sorb hydrogel applied at 7.1g per pot, and Soil Moist applied at 10.5g per pot. Plants were hand watered every other day with 100 mL of water for the first 4 weeks and then 200 mL of water for the remainder of the experiment. All plants received 31g of Nutricote 18-6-8. There was no effect of additive or substrate type on plant height or shoot dry weight. Although not significantly different, plants receiving the additive treatments were generally given a higher visual rating for all substrate combinations. Treatments had no effect on relative chlorophyll content. There was a significant interactive effect of additive and substrate type on weight of the container (substrate plus plant). The substrates containing 75% peat and coir had higher weights. Additives increased container weight for the substrates containing peat whereas addtivie effect was variable for coir-based substrates. There was also an interactive effect of additive and substrate type and substrate type by date on substrate pH. Substrate pH generally increased over the duration of the experiment for the peat containing substrate combinations, whereas coir containing substrates varied. Soil additives improved substrate water retention, with the effectiveness influenced by substrate type. Plant growth was unaffected during the duration of the experiment.