Fall pansy production is a staple for many growers. While pansies are a quick crop, several nutritional problems can occur that you should watch out for to have the most success possible.
High pH
One of the most common problems with fall pansy production is iron (Fe) deficiency. This is observed as interveinal chlorosis of the new foliage. There are a variety of causes for Fe deficiency including overwatering and high substrate pH. Growers should closely monitor these root zone conditions and target a root zone pH of 5.5-6.2 to prevent high pH-induced iron chlorosis and maintain a substrate moisture level of 2-4 on a 1-5 scale. Alert 12.34 provides additional resources about pansy pH problems.
Low pH
Due to the frequency of high substrate pH-induced iron deficiency, pansies are generally grown on the acidic side of the pH scale. A root zone pH of 5.5-6.2 is the recommended range. What happens if the substrate is too low? Symptoms include lower leaf purple-black discoloration (Fig. 2). With fall pansy production, the quick growing period usually means that there is little time for these symptoms to manifest. During normal active growth, observation of low pH problems is infrequent, and occurrence increases with slower winter-grown crops. Confirm the substrate pH values with a PourThru test. Low phosphorus concentrations coupled with cool growing can result in lower leaf purpling which can appear to be similar.
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