Before you purchase your new bush or bushes, you should be certain that you have an ideal location. Double Althea does best in full sun; however, it can do well with partial shade. You should have plenty of room for your althea to grow because these plants like to spread. Each one needs at least 6 feet of space around it to allow ample room for expansion.
This bush wants its feet in a well-drained soil. Dig a big hole and make sure to have plenty of loose, nourishing soil on hand to fill in the hole.
The soil (always improve poor soil) you surround your young shrubs roots with should be a combination of the native soil you removed and a quality, light compost that will nourish your new bush and provide for proper root aeration.
Now dig a hole about two times the size of your pot and the same depth as the root ball. Set the soil you have dug out aside and mix it compost. Remove the plant from its pot and gently loosen the root ball. Place the plant in the planting hole and replace the soil with the mix and gently pack down the dirt. To avoid planting to deep make sure the plant is at a position with the top most roots at the soil line.
Organic matter added to the soil and an adequate layering of mulch will generally provide azaleas with sufficient nutrients; therefore, frequent fertilizing is often not required. However, if there are low amounts of nitrogen in the soil, applying fertilizer may be necessary in order to prevent a nutrient deficiency. Symptoms of deficiency in azaleas include stunted growth, smaller greenish-yellow leaves, or early leaf drop. Fertilizing of these shrubs should take place in late spring to early fall.
For the first year it is a critical time for your new althea. It has not had time to establish itself yet and therefore is not as strong as an older shrub. To prevent the plant from dying, it must be watered twice a week on light soil and once a week on clay soil. Be sure to soak the entire root system deeply, this will take about 45-60 minutes.
For best growth and production, altheas should receive at least one inch of water a week. Since azaleas are so shallow rooted, we recommend that irrigation be installed when you first plant your azaleas. During dry spells, water is mandatory. If not properly watered during dry spells, flowers may be mitigated. Keep at least 4 feet around the shrub clear of grass and weeds, for less competition for water.
In general, do not prune spring-flowering shrubs such as azaleas and rhododendrons. If you need to reduce height, prune after flowering in the spring. Otherwise, just remove dead, damaged, or diseased branches anytime. On young and old plants, simply snap off spent flower stalks by bending them over until they break away from their stems. Be careful not to damage growth buds at the base of each flower stalk.