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Processed loblolly pine (Pinus taeda) wood has been investigated as a component in greenhouse and nursery substrates for many years. Specifically, pine wood chips (PWCs) have been uniquely engineered/processed into a nonfibrous blockular particle size suitable for use as a substrate aggregate. The objective of this research was to compare the dolomitic limestone requirements of plants grown in peat-based substrates amended with perlite or PWC. In a growth trial with ‘Mildred Yellow’ chrysanthemum (Chrysanthemum ×morifolium), peat-based substrates were amended to contain 0%, 10%, 20%, 30%, 40%, or 50% (by volume) perlite or PWC for a total of 11 substrates. Substrates were amended with dolomitic limestone at rates of 0, 3, 6, 9, or 12 lb/yard³, for a total of 55 substrate treatments. Results indicate that pH of substrates amended with ≥30% perlite or PWC need to be adjusted to similar rates of 9 to 12 lb/yard³ dolomitic limestone to produce similar-quality chrysanthemum plants. In a repeated study, ‘Moonsong Deep Orange’ african marigold (Tagetes erecta) plants were grown in the same substrates previously formulated (with the exclusion of the 50% ratio) and amended with dolomitic limestone at rates of 0, 3, 6, 9, 12, or 15 lb/yard³, for a total of 54 substrate treatments. Results indicate a similar dolomitic limestone rate of 15 lb/yard³ is required to adjust substrate pH of 100% peatmoss and peat-based substrates amended with 10% to 40% perlite or PWC aggregates to the recommended pH range for african marigold and to produce visually similar plants. The specific particle shape and surface characteristics of the engineered PWC may not be similar to other wood products (fiber) currently commercialized in the greenhouse industry, therefore the lime requirements and resulting substrate pH may not be similar for those materials.

Various soilless substrate components have been evaluated for many years to identify sustainable resources that do not negatively impact plant growth. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. In addition, the use of carbon adsorption for compound removal is widely used in groundwater remediation, municipal water filtration, and volatile organic compounds. Experiment one aimed to determine the impact of coarse biochar (<6 mm) on paclobutrazol efficacy when incorporated at 15% or 30% by volume in a peat-based substrate when compared with a perlite-amended substrate at the same incorporation volumes. In Expt. 1, a single paclobutrazol drench application of 0, 0.5, 1.0, 2.0, and 4.0 mg·L⁻¹ was applied to ‘Princettia Red’ and ‘Princettia White’ poinsettias (Euphorbia pulcherrima × Euphorbia cornastra). In Expt. 2, two different biochar particle sizes of coarse (<6 mm) and extra coarse (>6 mm) were examined at the same incorporation volumes as Expt. 1 and compared with a perlite-amended substrate at the same incorporation volumes. However, during Expt. 2, continual drench applications at times of irrigation of 0.0, 6.25, 12.5, 25.0, 50, and 100 μg·L⁻¹ (ppb) paclobutrazol were applied to pansy (Viola ×wittrockiana) ‘Matrix Blue Blotch’ and begonia (Begonia ×hybrida) ‘Big Red Bronze Leaf’. The efficacy of paclobutrazol drenches for controlling growth in all species was unaffected by the substrate composition regarding aggregate type or aggregate incorporation rate. Thus, even though biochar is often used for bioremediation and wastewater treatment, it did not negatively impact the efficacy of paclobutrazol drenches at the concentrations used. This research suggests that when biochar is used as an amendment to peatmoss it will not influence paclobutrazol drench efficacy when incorporated up to 30% by volume for the examined species.

Processed pine (Pinus sp.) wood has been investigated as a component in horticultural substrates (greenhouse and nursery) for many years. Specifically, pine wood chips (PWC) have been uniquely engineered/processed into a nonfiberous blockular particle size, suitable for use as a substrate aggregate. The purpose of this research was to determine if paclobutrazol drench efficacy is affected by PWC used as a substitute for perlite in a peat-based substrate. Paclobutrazol drench applications of 0, 1, 2, and 4 mg/pot were applied to ‘Pacino Gold’ sunflower (Helianthus annuus); 0.0, 0.25, 0.50, and 1.0 mg/pot to ‘Anemone Safari Yellow’ marigold (Tagetes patula); and 0.0, 0.125, 0.25, and 0.50 mg/pot to ‘Variegata’ plectranthus (Plectranthus ciliates) grown in sphagnum peat-based substrates containing 10%, 20%, or 30% (by volume) perlite or PWC. Efficacy of paclobutrazol drenches for controlling growth of all three species was unaffected by substrate composition. We concluded that substituting PWC for perlite as an aggregate in peat-based substrates should not reduce paclobutrazol drench efficacy, variability in PWC products indicates that efficacy should be tested before large-scale use. The variability results from wood components not being engineered and processed the same across manufacturers, meaning that they are often incapable of improving/influencing the physical and chemical behavior of a substrate similarly.

Processed pine wood (Pinus sp.) has been investigated as a component in greenhouse and nursery substrates for many years. Specifically, pine wood chips (PWC) have been uniquely engineered/processed into a nonfiberous blockular particle size, suitable for use as a substrate aggregate. In container substrates, nitrogen (N) tie-up during crop production is of concern when substrates contain components with high carbon (C):N ratios, like that of PWC that are made from fresh pine wood. The objective of this research was to compare the N requirements of plants grown in sphagnum peat–based substrates amended with perlite or PWC. Fertility concentrations of 100, 200, or 300 mg·L⁻¹ N were applied to ‘Profusion Orange’ zinnia (Zinnia ×hybrida) and ‘Moonsong Deep Orange’ marigold (Tagetes erecta) grown in sphagnum peat–based substrates containing 10%, 20%, or 30% (by volume) perlite or PWC. Zinnia plant substrate solution electrical conductivity (EC) was not influenced by percentage of perlite or PWC. Perlite-amended substrates fertilized with 200 mg·L⁻¹ N for growing zinnia, maintained a constant EC within optimal levels of 1.0 to 2.6 mS·cm⁻¹ from 14 to 42 days after planting (DAP), and then EC increased at 49 DAP. In substrates fertilized with 100 and 300 mg·L⁻¹ N, EC levels steadily declined and then increased, respectively. Zinnia plants grown in PWC-amended substrates fertilized with 200 mg·L⁻¹ N maintained a constant EC within the optimal range from 14 to 49 DAP. Marigold substrate solution EC was only influenced by N concentration and followed a similar response to zinnia substrate solution EC. Zinnia and marigold substrate solution pH was influenced by N concentration and generally decreased with increasing N concentration. Plant growth and shoot dry weight were similar when fertilized with 100 and 200 mg·L⁻¹ N. According to this study, plants grown in PWC-amended substrates fertilized with 100 to 200 mg·L⁻¹ N can maintain adequate substrate solution pH and EC levels and sustain plant growth with no additional N supplements. Pine wood chips are engineered and processed to specific sizes and shapes to be functional as aggregates in a container substrate. Not all wood components are designed or capable of improving/influencing the physical and chemical behavior of a substrate the same. On the basis of the variability of many wood components being developed and researched, it is suggested that any and all substrate wood components not be considered the same and be tested/trialed before large-scale use.

Preplant bulb soaks of flurprimidol, paclobutrazol, and uniconazole; foliar sprays of ethephon and flurprimidol; and substrate drenches of flurprimidol were compared for height control of `Anna Marie' hyacinths (Hyacinthus orientalis). Preplant bulb soak concentrations of flurprimidol and paclobutrazol were from 25 to 400 mg·L^-1, and uniconazole from 5 to 80 mg·L^-1. Height control was evaluated at anthesis and 11 days later under postharvest conditions. Ethephon (250 to 2000 mg·L^-1) and flurprimidol (5 to 80 mg·L^-1) foliar sprays were ineffective. Flurprimidol (0.25 to 4 mg/pot) drenches had no effect during forcing, but controlled postharvest height at concentrations ≥0.25 mg/pot a.i. with at least 4% shorter plants than the untreated control. Preplant bulb soaks resulted in height control with flurprimidol ≥25 mg·L^-1, paclobutrazol ≥100 mg·L^-1, and uniconazole ≥40 mg·L^-1; having at least 9%, 6%, and 19%, respectively, shorter plants than the untreated control. Based on our results, flurprimidol preplant bulb soaks have a greater efficacy than either uniconazole or paclobutrazol. Preplant PGR soaks are a cost-effective method of controlling plant height of hyacinths because of the limited amount of chemical required to treat a large quantity of bulbs.

Three experiments were conducted to determine the effectiveness of plant growth regulators (PGRs) on `Tete a Tete', `Dutch Master', and `Sweetness' narcissus (Narcissus pseudonarcissus). Ethephon foliar sprays (500 to 2500 mg·L<sup>-1</sup>) and substrate drenches of flurprimidol and paclobutrazol (0.25 to 4 mg/pot a.i.) did not control height during greenhouse forcing of `Tete a Tete' at any concentration trialed. Stem stretch was controlled during postharvest evaluation with ethephon foliar sprays ≥1000 mg·L^-1, flurprimidol substrate drenches ≥0.5 mg/pot a.i., and paclobutrazol substrate drenches of 4 mg/pot a.i. A second experiment investigated preplant bulb soaks of flurprimidol (10 to 40 mg·L^-1) applied to `Dutch Master' and `Tete a Tete' narcissus bulbs. Flurprimidol preplant bulb soaks controlled postharvest stretch on `Tete a Tete' and `Dutch Master' at concentrations ≥15 and ≥10 mg·L^-1, respectively. A third experiment was conducted with paclobutrazol (75 to 375 mg·L^-1) on `Tete a Tete' and `Dutch Master' and three concentrations of flurprimidol on `Sweetness' to determine optimal soak recommendations. Paclobutrazol preplant bulb soaks ≥75 mg·L<sup>-1</sup> controlled postharvest stretch of `Tete a Tete' and `Dutch Master', while 37.5 mg·L<sup>-1</sup> of flurprimidol controlled postharvest stretch of `Sweetness'. Based on the results of these experiments, growers can now select a PGR to help control excessive plant growth.

Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and B were induced in `Osaka White' ornamental cabbage (Brassica oleracea var. acephala L.) plants. Seedlings were planted in 4.7-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested for tissue analysis as well as dry weight when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Root architecture was also recorded for the plants treated with the solutions. The containers were replicated three times for each of the two harvests and were randomized in a complete-block design. Deficiency symptoms for all treatments were observed within five weeks. The most dramatic expression of foliar symptoms occurred with N (a purplish tinge on underside of lower foliage leading to necrotic margins on the mature leaves), P (elongated internodes and a purplish tinge on underside of mature leaves), K (compact internodes with chlorotic lower foliage leading to necrotic patches on the leaf margins and blade), Fe (bright yellow upper foliage leading to a bleach white appearance), Ca (complete meristem necrosis with lower foliage becoming chlorotic then necrotic), and B (deformed young leaves and fully expanded leaves becoming thick, leathery, and brittle). The dry weight of plants treated with solutions not containing N, P, Ca, Fe, or B was significantly lower when compared to the control. Foliar tissue concentration data will assist plant tissue analysis laboratories in establishing foliar symptom standards for grower samples.

The margin of error in pinpointing the difference in deficiency symptoms between calcium and boron is high. Several experiments were conducted in the greenhouse to induce as well as to differentiate the exact foliar and root symptoms of Ca and B. The experiments were conducted with modified Hoagland nutrient solutions. The treatments were with or without Ca or B salts for inducing total deficiency symptoms. Symptoms were expressed on the upper part including the growing point of the plant. In absence of Ca, marigold and zinnia plant heights were reduced by 58% and 37%, respectively, from the control. However, the reduction in height was only in the 27% and 25% range for B deficiency. Ca deficiency was noted as a blackened region on the leaf blade (early stage symptoms) which progressed into necrotic spots on the newly formed leaves. Severe necrosis, was observed on the growing point with advanced Ca deficiency. B deficiency results in a leathery and gray color in zinnia, needle like and narrow leaflets in marigold. The leaf blades were brittle in all B deficient species. B deficient plants roots were stiff and leathery and lateral roots possessed black nodule like endings at the tips. The Ca deficient roots expressed less side branching and at the advanced stage the roots were shorter and fewer with severe necrotic symptoms. The above initial and advanced deficiency symptoms appeared earlier in treatments without Ca than B. Images of Ca and B deficiency symptoms, as well as tissue concentration values will be presented.

The objective of this research was to quantify the effects of phosphorous (P) concentrations on the growth, development, and tissue mineral nutrient concentrations of four popular culinary herbs commonly grown in containers. Seedlings of sweet basil (Ocimum basilicum ‘Italian Large Leaf’), dill (Anethum graveolens ‘Fernleaf’), parsley (Petroselinum crispum ‘Giant of Italy’), and sage (Salvia officinalis) were individually transplanted to 11.4-cm-diameter containers filled with soilless substrate comprising canadian sphagnum peatmoss and coarse perlite. Upon transplanting and throughout the experiment, seedlings were irrigated with solutions containing 0, 5, 10, 20, or 40 mg·L⁻¹ P; all other macro- and micronutrient concentrations were the same across P concentrations. Plants were grown for 4 weeks in a greenhouse; after that time, data were collected. Relationships between height and width and P concentrations were nonlinear for all four species; height and width increased as P increased to more than 0 mg·L⁻¹ until the species-specific maxima; after that time, no further increase occurred. The same trend was observed for the branch length of sweet basil and sage, and for internode length, leaf area, and shoot dry mass of all four species. Although visible P deficiency symptoms were observed for plants provided with 0 mg·L⁻¹ P, there were no signs of P deficiency for plants provided with ≥5 mg·L⁻¹ P, even though tissue P concentrations were below the recommended sufficiency ranges. As a result of this research, containerized sweet basil, dill, parsley, and sage can be provided with 5 to 10 mg·L⁻¹ P during production to limit growth and produce plants without visible nutrient deficiency symptoms that are proportional to their containers.