News » 30.06.2026 - When rain washes out the feed in outdoor mum production

Rainfall during outdoor garden chrysanthemum (Chrysanthemum ×morifolium) production can create several challenges throughout the crop cycle. Repeated or heavy rain can move substantial volumes of water through containers, thereby leaching soluble fertilizer salts from the substrate and consequently lowering rootzone electrical conductivity (EC). As a result, garden mums may remain wet while lacking sufficient available nutrition to maintain growth and crop uniformity.

Garden mums generally require medium to high fertility, often 150 to 300 ppm N during active growth, to maintain canopy development and crop uniformity. Fertilizer concentration and application frequency should be adjusted according to crop stage, substrate EC, weather conditions, and the fertility program being used. When fertilizer salts are repeatedly leached from the substrate due to rainfall and not replaced, plant growth can stall, foliage can become chlorotic (yellow), and plants can finish smaller or less uniform than expected. Extended periods of depleted fertility can also contribute to stress-related problems, including premature crown budding and foliar discoloration (yellowing or reddening).

The PourThru method provides a practical, nondestructive way to monitor substrate pH and EC throughout outdoor garden mum production. Because container moisture alone does not indicate whether plants have adequate nutrition, increase testing frequency after repeated or significant rainfall events to determine whether fertilizer salts have leached from the substrate. Regular monitoring helps determine when fertilizer should be replenished, whereas container moisture should be assessed before making a corrective fertilizer application.
 

Source: www.floraldaily.com

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