Native roots help Hydrangea arborescens cultivars like Incrediball tolerate a wide range of growing conditions and soils. Think of them like any other shrub in your landscape–undemanding and easy to grow.
Incrediball smooth hydrangea is hardy in USDA Zones 3-8. In all but the warmest climates, it will be the most vigorous and produce the most flowers if you grow it in full sun; some afternoon shade is best in the South. It will grow and bloom in the shade in the North too, but its flowers will be smaller. No matter where you garden, your smooth hydrangea will benefit from a 2-3 inch layer of mulch to keep the roots cool and moist.
Smooth hydrangeas tolerate most soil types as long as they are well-drained. This plant doesn’t grow well in soggy soil so if that sounds like yours, you may need to improve the drainage before planting. While many types of hydrangeas prefer acidic soil (pH less than 7.0), smooth hydrangeas can live in acidic and neutral (pH 7.0) soils.
If you are planting a hedge of Incrediball hydrangeas and you’d prefer the plants to grow together into one solid row, space them about 4 feet apart. If you are planting a single specimen and don’t want other plants to grow into it, give it 4 to 6 feet of room to spread over time. Keep in mind that this species of hydrangea takes a few years to mature and really show its full personality.
When planting, dig the hole about twice as wide but just as deep as the container it is growing in. If the roots are densely circled around when you take the plant out of the pot, loosen them up a bit to break the “root memory”. This will encourage them to grow outward instead of continuing to grow in a circular pattern.
Set the plant in the hole, making sure that the top of the rootball is level with the top of the surrounding soil. Then backfill the hole with the soil you dug out. Press it down with your hand firmly to eliminate any big air pockets around the roots.
Lastly, water the plant again to help the soil settle. Spread some mulch around the base of the plant, taking care to keep it from touching the plant’s stems. The mulch will help to retain soil moisture and protect the roots during winter.