To determine the bloom habit of your hydrangea, first determine the type of hydrangea you have. The most common types grown in North America are:
Bigleaf hydrangea (Hydrangea macrophylla), which includes the mophead and lacecap hydrangeas Mountain hydrangea (Hydrangea macrophylla subspecies serrata) Panicle hydrangea (Hydrangea paniculata) Smooth hydrangea (Hydrangea arborescens) Oakleaf hydrangea (Hydrangea quercifolia) Climbing hydrangea (Hydrangea petiolaris)
Another determining factor for hydrangea bloom time is the local climate. In the South, an oakleaf hydrangea flowers in early summer while in a cooler location in the United State Midwest or Northeast, it won’t start blooming until later in the summer. If your hydrangea is not blooming, use the following checklist to troubleshoot and fix the cause.
1. Potted Gift Hydrangeas Usually Don’t Rebloom
Planting hydrangeas in the garden that have been grown and sold as gifts for Easter or Mother’s Day, often in small pots wrapped in a decorative foil, usually have a low chance of survival, let alone blooming. They have been forced into early bloom and are conditioned with lots of fertilizer; often, the hydrangea variety is one that is not hardy for your area.
2. Hydrangea Is Not Hardy In Your Climate
Hydrangeas vary in their hardiness, with bigleaf hydrangeas being the least hardy and panicle hydrangea being the most cold tolerant. If a hydrangea does not bloom, it could be that it is not suitable for your hardiness zone. While the root system might survive winter, if the variety produced buds on last years stems, the buds are killed by extreme cold, and thus, no blooms the following year.
3. Late Spring Frost
If the hydrangea is suitable for your climate zone, an unseasonably late spring frost or cold temperatures can kill or stunt the flower buds and result in a summer without blooms. Keep an eye on the weather forecast in the spring and when frost is in the forecast, protect the hydrangea with burlap, sheets, or blankets for the night. Remove the coverings promptly the next morning and repeat as needed.
4. Inadequate or Too Much Sunlight
To bloom, most hydrangeas require at least three to four hours of direct sunlight per day, ideally in the early morning or dappled sunlight in the afternoon. Locations with full afternoon sun are usually too intense. Both too little and too much sunlight can affect blooming. The panicle hydrangea can tolerate the most sun exposure.
5. Timing of Pruning
When it comes to pruning hydrangeas, timing is everything. And, again, it all depends on the type of hydrangea and when it sets its flower buds. Some types of hydrangeas set buds and bloom on old wood, others on new wood, and some on a combination old and new wood. Without knowing which hydrangea you are pruning, you risk removing the stems that will produce buds and blooms. Make sure to follow the instructions for pruning hydrangeas according to type.
6. High-Nitrogen Fertilizer
When hydrangeas are given fertilizer with a high nitrogen content, they produce mainly foliage and no flowers. What they need is a fertilizer that is high in phosphorus (P) because phosphorus promotes blooming. This type of fertilizer is often labeled as a bloom booster and it should be applied in the early spring and again in mid-summer. Hydrangeas do best in soil with an acidic pH. You can use a fertilizer for acid-loving plants but be aware that might have a higher nitrogen content.
7. Lack of Moisture
If your hydrangea does not bloom, it could be that it was watered insufficiently or under drought stress the summer before. Think back to last summer’s weather conditions to determine if this could be the cause. To prevent this from happening again, make sure the soil is continuously moist but well-drained.
8. Newly Planted Hydrangea
It can take a hydrangea a couple of years to become fully established. If you provide the necessary care and plant it in the right location, it might just take time and patience to see it bloom.
