The Right Variety
Not every hydrangea variety will thrive indoors. However, hydrangea macrophylla is best suited for indoors. It is commonly called a mophead hydrangea and comes in many colors. “It’s one of the hardiest hydrangeas,” say the experts at Plants.com. “And it is great for growing indoors because it is suited for containers, it’s covered in blooms, and easy to grow.” Hydrangea macrophylla features large bloom clusters nestled among textured, rich green leaves. They are especially popular indoors because the plant blooms for months and makes a great table centerpiece.
Light
Hydrangeas have a reputation for being shade-loving plants. The truth is, although they tolerate shade, they need bright, indirect light. In the outdoors, they need protection from direct sun, so they grow well under tree canopies. However, the overall ambient light outdoors will be of higher quality than in most indoor environments. Therefore, to successfully keep hydrangeas thriving indoors, you will need to provide them with high-quality, bright, indirect light. This light can come from a south-facing window, which will offer sunlight throughout the day, or from an east-facing window, which will receive morning sunlight. “Plenty of light is needed to keep them blooming. But be careful not to put them in direct afternoon sun, or the leaves and blooms will burn.”
Water
A pot with a drainage hole is a must for hydrangeas because it allows the soil to drain after watering. Proper drainage will prevent root rot and other fungal diseases from harming your plants. Like most potted plants, watering will depend on how fast the soil dries out and if it’s in bloom or not. It’s best to test the soil’s moisture level 3 inches into the soil. If it feels semi-dry to the touch, water thoroughly until you see the water run out of the bottom of the pot. While the plant is in bloom, hydrangeas need water more often. The flower heads will droop slightly when they are thirsty. When the bloom cycle is over, they will require less water but should never dry out completely. If possible, use distilled water or rainwater, because most tap water contains chlorine and other elements that can affect the blooms.
Soil and Fertilizer
Hydrangeas do best in well-draining, slightly acidic soil. The acidity of the soil will affect the color of the plant’s blooms. A pH level of 5.5 or lower (more acidic) will produce blue flowers, while a pH level between 5.5 and 6.5 will create purple/pink blooms, and a pH level of 7 or higher will result in red blooms, explain the pros at Plants.com. However, the color of the blooms is also dependent on the variety you have. Fertilize indoor hydrangea plants weekly during active growth and blooming. Once the flowers die back, start fertilizing the plants just once a month, and stop feeding altogether in early fall.
Pruning
The variety of hydrangea determines when the plant should be pruned. Hydrangea macrophylla does not need hard pruning to encourage blooms on new branches the following year. “The best time to prune is immediately after flowering stops in summer. Do not prune in fall, winter, or spring, or you could be cutting off new buds.” You can remove spent flowers to help keep the plant looking tidy. When you do prune, cut back dead or weaker stems. It is essential to keep some of the old wood/stems so you will have blooms again. The experts at Plants.com have answers to the most commonly-asked hydrangea questions and tips to help you get more out of your indoor potted hydrangeas.
Can I plant my indoor hydrangea outdoors later?
Indoor-grown hydrangeas can be planted in the garden. Before moving them outdoors, make sure the threat of frost has passed. Choose a partially sunny spot that can accommodate a 3- to 4-foot shrub. Then apply fertilizer for acid-loving plants as directed.
How can I make the blooms last longer?
Water frequently when the plant is blooming so the soil doesn’t get dry, but do not overwater. Keep the plant in a cool room during blooming. If the leaf edges turn brown and crispy, the room may be too warm. Keep the plant away from drafts and heat sources. If the leaf edges become brown, it could also indicate salt buildup on the root systems. If this is the case, you may have to rinse the roots and replant them in fresh soil. If the blooms look dry, take a mister and lightly spray them. Hydrangeas are one of the few plant varieties that can draw moisture through their petals.
Will indoor hydrangea varieties rebloom annually?
With special care, indoor hydrangeas can thrive annually. Once the flower heads start to turn brown, trim them off. If not bringing them outdoors, you will need to force a period of dormancy during fall and winter. Move the plant into an unheated room with temperatures around 45 F. Keep the potting mix on the dry side, but water lightly as needed to prevent wilting.
