I just purchased two Shooting Star hydrangeas, also known as Fiji Waterfalls, or Fireworks. We live in zone 7. Should I plant these in a large pot outdoors and bring them inside during the winter? Or can I plant them in my flower garden? Will this plant ever need pruning?
Shooting Star Hydrangea belongs to H. macrophylla-Lacecap. It is hardy in zones 7-9, (20-50F) in dormant state.
The flattened flowerhead has white double petaled “stars” (flowers) that shoot from the flower like fireworks. The flowers stay white for 4-6 weeks and then mature to a light green hue. Quite impressive!
In zone 7-9 you can plant it outdoors in well drained soil, where it will get morning sun and afternoon shade. Add a few inches on mulch around the plant to keep it evenly moist during the summer. In warmer climate more shade is preferred.
In marginal climates, zone 7, if an unusual freeze is imminent, cover it with a frost blanket to protect the flower buds.
The best time to fertilize is in late winter/early spring before bud break. Spread the well-balanced fertilizer (10-10-10) or a slow-release fertilizer (Osmocote etc.) around the base of the plant. See package directions as to the rate amount. You can also feed during the growing season but no later than Aug 1st. as that would promote new growth that may not have enough time to harden off before the winter.
Another option is to repot it in a larger container, let it develop a good root system and plant it in the fall. If you get an unusual freeze cover it with a blanket to protect the flower buds.
Shooting star hydrangea belongs to the H. macrophylla family and blooms on old wood so care must to taken when pruning. Prune (deadhead) after bloom any fading flowers by cutting below the flower head. To maintain size and thin out old branches, cut back when needed. Hard pruning should not be done after mid-August.
In cooler regions zone 6 or lower, bring it indoors for the winter.