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Gasified rice hull biochar (GRHB) is a byproduct of rice production, where rice hulls are gasified to generate energy for other aspects of rice processing. Other research has shown that GRHB up to 10% (v/v) in a soilless substrate can provide much, but not all, of a potted floriculture crops’ phosphorus and potassium needs. The objective of this research was to determine the effect of higher GRHB rates on floriculture crop nutrition and growth. Two experiments were conducted with GRHB rates ranging from 0% to 30% (v/v) of a soilless peatmoss-based substrate. Geranium (Pelargonium ×hortorum ‘Maverick Red’) and tomato (Solanum lycopersicum ‘Megabite’) were grown in 10-cm diameter pots with amended substrates. Addition of GRHB up to 30% affected the physical properties of the peatmoss-based substrate by increasing container capacity (CC) and decreasing unavailable water (UAW). Summarizing across the two experiments, amending a peatmoss substrate with 15% and 20% GRHB provided sufficient P and K for production of geranium and tomato in soilless substrates over a 5 to 6 week production cycle. However, GRHB did not provide a sufficient source of micronutrients to support acceptable crop growth. Geranium responded negatively to high rates (>10%) with reduced shoot and root growth, while tomato responded positively to higher rates with increased shoot growth. Higher rates of GRHB (>10%) can be recommended for some crops, but not all.

Loropetalum (L. chinense) cv ‘Blush’, ‘Burgundy’, and ‘Pizzazz’ were grown for 16 months using different rates and application schedules of a 17–7–12 slow‐release fertilizer. Rates were45,68,or 91 g pot1, each applied once in the Spring, or as a split application, half in the Spring, and half in the Fall. A simple format for reporting fertility, methodology used in tissue sampling, and analytical methodology was developed and used. Fertilizer treatments did not affect significantly growth and color ratings 4 and 12 months after potting (p>0.30). ‘Burgundy’ was significantly the fastest growing cultivar. Yet, all plants from all treatments and cultivars were of commercial quality 12 months after potting. Foliar nutrient content was significantly affected by fertilization treatment for most of the essential elements (p 0.10). However, differences due to fertilizer treatments were of limited practical importance as they did not follow the trends in fertilizer rates. Bas...