Ebb and flow production of petunias and begonias as affected by fertilizers with different phosphorus content

Water conservation is increasingly important for growers in the United States, but there is little information on the use of alternative irrigation systems, such as ebb and flow, for the production of bedding plants. The objective of this study was to quantify the growth of Petunia xhybrida Hort. Vilm.-Andr.'Blue Frost' and Begonia xsemperflorenscultorum Hort. 'Ambassador Scarlet' grown in an ebb and flow system in three soilless media and fertilized with P at 0, 50, or 100 mg.L-1 in the fertigation solution. After 5 weeks, plants grown with 50 or 100 mg.L-1 P had greater dry weight, height, and width than plants grown with 0 mg.L-1 P. Begonias grown with 50 or 100 mg.L-1 P had 38% more flowers than did those grown without P. Petunias flowered 4 to 7 days earlier when no P included in the fertilizer. Growing media had little effect on the plants: Begonias grown in Metro-Mix 220 had more inflorescences than those grown in Metro-Mix 366Coir. Changes in electrical conductivity (EC) and pH of all three media were similar over the course of the experiment. The EC dropped during the third and fourth,reek and rose again in the fifth week. The pH of the leachate from all three media dropped by an average of 1 unit during the experiment. The results indicate that petunias and begonias may be grown successfully: with ebb and flow irrigation, using a variety of fertilizers and growing media. However, P must be included in the fertigation solution for optimal plant quality.