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Wednesday - March 24, 2010

From: San Marcos , TX
Region: Southwest
Topic: General Botany, Planting, Trees
Title: Why is my 3 year old Redbud not flowering in San Marcos, TX?
Answered by: Jimmy Mills


My Cercis canadensis var. mexicana, purchased at the Lady Bird Johnson Wildflower Center, is 3 years old, very robust, but has never bloomed. Any explanation?


Mr. Smarty Plants thinks that a three year old, robust red bud is old enough to flower, so lets look elsewhere for an explanation. Two factors that can influence flowering are sunlight and fertilizer. Is it getting enough sunlight? The light for requirement for Cercis canadensis var. mexicana (Mexican redbud) calls for full sun to partial shade. The more sun, the better the flowering (at least 6 hours per day).

Flowering is aslo affected by the nutrient balance in the soil; particularly the ratio of nitrogen to phosphorus (the N/P ratio). If the N/P ratio gets too high, flowering can be inhibited. This can happen if your tree is receiving too much regular lawn fertilizer (which is generally higher in nitrogen). The pH of the soil can affect the availability certain nutrients.

This link from Colorado State University Extension provides good information about phosphorus fertilizerrs.




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