There are thousands of motley ofazaleas(Rhododendronspp . ) , the most stout of which can be originate as far north as United States Department of Agriculture works hardiness zone 3 . Other azalea varieties get well in climates that do not know frost , to zone 10 . With such a wide climate orbit , there is an azalea for every part . With few fertilization requirements , azaleas are a low - maintenance flowering bush . To keep azalea sizable and blooming , keep them well mulched and ensure the soil is more or less acidulent .
Improving Soil pH for an Azalea
The key to keeping azalea levelheaded is experience the correct soil acidity . Soil that is too acidic or too alkaline will not bring on the best efflorescence . azalea like a soil pH of 4.6 to 6.0 , which is slimly acidulent . Garden centers sell soil - examination kits which can determine the acidulousness of soil around an existing azalea or an area where an azalea is to be planted .
For grunge that is too alkaline , above 6.0 , lend 3 snow leopard of elemental sulfur per azalea flora to lower the soil pH one point . This can be done once a year until the ideal pH is reached . For existing azalea President George W. Bush , both late planted and well - lay down plant , work the S into the top few inches of soil around the industrial plant in an area about 6 inches to 12 column inch off from the stem . Be careful not to damage plant roots .
It is rare for dirt to be too acidic , but if it is below 4.5 , add together 12 ounces of lime per azalea plant to fire pH by one power point , work it in the same way sulfur is added once a year .
Planting New Azaleas
Test territory acidity before plant Modern azalea and tally atomic number 16 or calcined lime as needed at the sum of money listed previously . Work the amendments into the top few inch of grease before planting . Ideally , amendment are worked into the soil a few weeks before planting , but can be add up to the daytime of planting if necessary .
Fertilizing Azaleas
While azaleas are not heavy feeders — they do not require a fate of nutrients in the soil to perform well — they may expose sign of a nutrient insufficiency . If parting bug out turning yellowish between the venous blood vessel , prey them a fertilizer specially formulated for azaleas , such as a30 - 10 - 10 mixture at a charge per unit of 1 tablespoon per congius of water per plant , but follow recording label directions . Fertilize established plantsone timewhen they are sleeping , between late descent and early spring . Do not fertilize newly planted azaleas , as this may stress the plant by force it to put out too much raw ontogeny on roots and stems too quickly .
For azalea that are performing well and do not show signs of nourishing deficiency , it is not necessary to fertilize . Keep azalea mulched with 4 inches of organic matter such as pine needles , leaf or wood chip to provide a steady supply of decompose matter to feed the bush . Do not mulch with inorganic mulch like rocks or arctic mulch . This can cause the soil to retain too much water and does not furnish the necessary nutrients .
