Bud Set of Azaleas, Rhododendron & other "Acid Lovers"
Welcome to our first weekly column which is actually our second column. In early May, I wrote our first column as we approached the airing of our Web site. Well, we finally made it! Ellen has worked hard to develop this Web site and will be available to help you on a day-to-day basis.
Our columns will be archived for your reference. I encourage you to go back and read the first column titled "Drought Awareness". Ironically, we have received a phenomenal 14 plus inches of rain in our area in the last 60 days since I wrote the column, but the information should still be of value.
Most of the azaleas and rhododendrons have now finished treating us to a beautiful spring of spectacular blooming. Some exceptions to this rule would be the later blooming Satsukis and Gumpos azaleas, but for the most part, these plants have finished blooming for the year.
Azaleas and rhododendrons are earnestly setting about the business of preparing for next year's bloom season right now. These plants set next year's buds two to three months following bloom, so if you have not pruned you must do so now or not at all. Last call!
The nutrient phosphorus is vital to the production and setting of buds. When you buy fertilizers they may say "10-6-4", etc. The "10" is the nitrogen, the "6" is the phosphorus, and the "4" is potash. Nitrogen and potash tend to have a relatively high salt content which can cause damage if applied excessively or at the wrong time of the year, such as mid-summer. Phosphorus, on the other hand, has a low salt content and can be safely applied in liberal doses, even in the hot summer.
One reason to spoon feed azaleas and rhododendrons phosphorus is to ensure its availability. These plants are "acid lovers" meaning that they have a lower pH or "acidic" soil. This acidity will bind phosphorus to soil particles which deprives the plant access to the nutrient, thus the need to apply the phosphorus at the right time for maximum availability.
In addition to azaleas and rhododendrons, other plants such as dogwood, mountain laurel, deciduous azaleas, and red buds are also acid lovers which set their buds in July or August. These plants will also benefit from an application of phosphorous in mid to late July.
Having said all of this, I recommend you acquire some Triple Super Phosphate 0-46-0 and apply this by mid to late July to enhance wonderful blooms next spring. Be sure to keep even moisture in the soil of your plants to ensure the maximum set of buds. Drought or drowning will yield a poor bud set. Here's to beautiful blossoms next year!
Andy Lynn