How to Grow Hydrangeas Quickly Indoors

Plant hydrangeas in spring to take advantage of their natural summer growing season. This planting season also allows for warmer temperatures and natural sunshine for efficient, simple care. Wait for the frost to lift and night time temperatures to reach 60 to 65 degrees F for the planting.

Prepare large 10- to 15-gallon pots and containers for indoor hydrangeas. Large pots give hydrangeas balance and room for quick root growth, and allow for long-term growth without transplant. Use only pots with drainage holes, as hydrangeas rot and die in standing water.

Mix planting soil of one part organic compost or sphagnum peat moss to one part bark-based potting soil and one part sand. Hydrangeas need rich, loose and moisture-retentive soil for quick, healthy growth. Fill each pot two-thirds full of potting soil, to leave at least 1 to 2 inches of space for watering.

Plant the hydrangeas one per pot, in holes deep and wide enough for their root balls. Pack soil mixture down around their roots to secure the plants. Hydrangeas do best in slightly shallow plantings, which give the roots access to air and moisture.

Put the hydrangeas in indoor sites where they receive bright, indirect sun all day or morning sun and afternoon shade. The shrubs need at least three hours of sunlight daily for best growth and blooming. Don't put them in all-day sun or near heat sources; hot air and sun dries hydrangeas foliage and damages growth.

Water the hydrangeas with 2 to 3 inches of water every four to five days to maintain soil moisture. Indoor plants dry more quickly than outdoor plants and require closer supervision in regard to moisture. Hydrangeas won't grow in tight, dry soil.

Give hydrangeas water-soluble 8-8-8 or 10-10-10 fertilizer in early spring, late spring and mid-summer to encourage continued growth and blooming.