5 Mistakes You’re Probably Making With Your Potted Azalea
Specialty potted azaleas shine this time of year, and the right situation and care keep them looking their best. To extend the colorful show, join gardening expert Katherine Rowe in avoiding common mistakes when housing potted azaleas indoors.
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Potted azaleas brim with buds and blooms in winter, showing color in an otherwise quiet time for many floriferous plants. Florist selections this time of year arrive in sweet pinks, purple, red, white, and salmon, with evergreen leaves in a giftable package. They usually represent two species and their hybrids among the Rhododendron genus, R. simsii (Formosa azalea) and R. ponticum (Hiryu azalea).
These, and many, azaleas are native to eastern Asia and grow as understory evergreen shrubs in mild-climate woodlands with rich, acidic soils. North American native azaleas are hardy across zones and delight with a spring show in woodland borders.
But, the mostly deciduous shrubs differ from the decorative pots we find around holiday time. Growers force potted species to bloom in winter by carefully controlling temperatures and managing growth. Otherwise, a spring and early summer bloom time is the usual cycle.
In addition to florist specimens, you may be overwintering a potted shrub that spends summer outdoors but moves inside for winter protection. In this case, cut way back on watering and expect some normal leaf drop as it transitions to indoor and seasonal conditions.
Temperature, potting media moisture, and lighting are particularly important for flowering. Reducing alkalinity, too, plays a role in continued health. Potted azaleas, in all their perfectly timed blooming, come with a few unique care needs, and avoiding the following mistakes will ensure that they thrive.
Keeping Them Too Warm
We’re used to azaleas growing as woodland shrubs in warm, humid climates, but it is a mistake to keep potted specimens too hot. At their natural spring bloom time, temperatures are cool and crisp. Cool temperatures promote the best budding and longest-lasting blooms. Hot and dry conditions, any time of year, cause stress and deterioration. In winter, we may be keeping our indoor azaleas too cozy.
Optimal daytime temperatures range from 60-68°F (16-20°C), with nighttime temperatures near 50-55°F (10-13°C). Temperatures at 75°F (24°C) or higher indicate a warming spell, and buds and flowers may drop as roots warm and soils dry more quickly.
Cold temps below 50°F (10°C) also risk slow development. Temperatures near 40°F (4°C) result in bud loss, while near-freezing conditions can damage leaves and stems.
Place pots in a cool room or near a window to experience lower temperatures (avoiding touching frosty glass panes). A cool indoor environment helps the flowers last longer. In warm situations, they’ll open and drop more quickly.
Winter Drafts
Most houseplants are averse to drafty situations, whether cold blasts from open doors or windows or heated air from fireplaces and central heat. To avoid this common mistake, keep potted azaleas away from drafts to prevent drying air and drastic changes from hot to cold. Sweeping fluctuations may inhibit blooming and lessen humidity, which is important for healthy azaleas.
Humidity around 50% or higher is best, and while this is average in many households, winter conditions can be more drying. If you notice yellowing leaves with crisping edges, first check soil moisture. If the media is evenly moist, low humidity may be the culprit.
To raise the immediate humidity, group houseplants. Or, place the container next to a tray of pebbles filled with water. The water evaporates around the pebbles, providing extra ambient humidity.
Letting Soil Dry
Potted azaleas do best with even moisture and it is a mistake to let them dry out between watering sessions. They also don’t do well in soggy, oversaturated conditions. So, striving for that even balance is key. Aim to water when the soil surface begins to feel dry to a depth of about half an inch, but not much lower. Azaleas have fine surface roots sensitive to drying out, and you’ll likely see quick wilting.
Florist azaleas often come in a peat moss potting media. When peat dries, it takes time to rehydrate. If your peat-based mix experiences significant drying, rehydrate it by soaking the entire pot. Submerge it in a sink or bucket of lukewarm water for 15 minutes. Let it drain thoroughly after soaking. Continue with a regimen for even moisture, watering when the media begins to dry on the surface.
The growing environment, potting media, and plant size determine how often to water, but the frequency is usually about once a week. Water deeply until it runs through the pot’s drainage holes. Remove any catchment trays or saucers after the pots have time to drain; excess water may draw into the pot and create wet roots.
Too Much Light (or Not Enough)
Along with keeping the bloomers too warm, they may be basking in too much light. Indoor azaleas thrive in bright, indirect light. Four to six hours of indirect sunlight sustains the energy needed to flower.
Place pots near an east-facing window or, in cold climates, a south-facing winter exposure. Use a curtain to filter direct sunlight – it can burn leaves and petals. Move them a few feet away from the window to lessen the intensity.
Conversely, low or dim light presents a challenge. The azaleas won’t flower, and growth slows as photosynthesis becomes more limited.
Using Tap Water
If you live in an area with hard water, your potted specimen may experience sensitivity to lime in the tap water. Tap water in hard water systems may contain alkalinity in the form of dissolved sodium bicarbonate, which is toxic to azaleas. Azaleas do best in acidic soils with a low pH, and alkalinity raises the pH and presents the opposite environment.
If you have hard water, rainwater or bottled water is best. You can also add one tablespoon of vinegar per gallon of water to reduce alkalinity. Water with room temperature or tepid water to avoid shocking the roots.
The Wrong Fertilizer at the Wrong Time
With their alkalinity sensitivities, you may be using the wrong fertilizer or applying it at the wrong time. Increased alkalinity caused by overfeeding can lead to iron deficiency. Overfertilizing or using the wrong type of fertilizer can cause toxicity. Alkaline soils have high pH levels (above 7.5). The sweet spot for azaleas is an acidity between 4.5 and 6.0, and adjusting soil pH makes iron available.
Alkalinity blocks access to nutrients, leading to yellowing leaves, a lack of vigor, and eventual decline. Organically rich soils with good drainage (including pine bark chips or horticultural sand) are a good foundation.
When it comes to fertilizer, a tailored formula for acid-loving plants provides nitrogen in the beneficial form of ammonium nitrate over common nitrogen. Garden sulfur and iron chelates are other amendments to correct soil deficiencies.
If you’ve just received a potted azalea in bloom, don’t make the mistake of fertilizing before spring, if at all. If you plan to keep it to enjoy beyond the season or are nursing an existing azalea, use a specialized acidic formula (for rhododendrons, hollies, camellias, and the like).
Begin fertilizing in early spring as new growth emerges. A granular or liquid feed works well. Granules need reapplication every two to three months, while liquids absorb quickly and require more frequent application. Apply it every other watering session in the warmer months. Stop fertilizing in late summer/early fall as plants prepare for budset during cooler months.
