Worried that your hydrangeas won’t bloom this summer? A hydrangea not blooming can be frustrating. Usually when a hydrangea won’t flower, there are common problem with some simple solutions. To get hydrangeas to bloom this summer, Express.co.uk has spoken to two gardening experts who have shared several mistakes to avoid when caring for hydrangeas.
1. Pruning extensively
According to Melvin Cubian, PlantIn’s in-house gardening and house plant expert, some hydrangea varieties do not tolerate overpruning. He claimed that this can “reduce the number of blooms in the flowering season”.
This is because the plant will likely focus more on the growth of new shoots rather than bearing flower buds. Instead, the expert advised: “Consider pruning only the diseased branches and no more than a third of the plant’s total size.”
2. Wrong amounts of shade and sunlight
Melvin urged that sun is important for flowering as plants highly depend on light energy to produce simple sugars as their food source.
He warned: “Without enough light, it cannot process food needed for growth and reproduction.
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“While hydrangeas are fine with shady spots, consider placing your plant in a bright location with direct or indirect light to increase the number of blooms.”
However, Nastya Vasylchyshyna, resident plant expert for the NatureID, gardeners need to “avoid prolonged direct sun exposure” for their hydrangeas as it can cause “leaf scorch and stress”.
The expert recommended: “Plant hydrangeas in well-lit areas with bright but diffused sunlight, for example, in the eastern, southwestern, or western part of the garden.”
3. Wrong use of fertiliser
While giving hydrangea complete fertilisers is not bad at all, an incorrect NPK (nitrogen, phosphorous and potassium) ratio may “delay and reduce the number of flowers”, according to Melvin.
He said: “Suppose more N is applied; it will rather continuously grow more leaves and branches than flowers. Try looking for a fertiliser ratio with a higher P (i.e., 10-20-10) to induce more blooms.”
When to fertilise these plants is just as important, according to Nastya. She said: “Feed your plant with liquid fertilisers (add them to the water you use for watering) before the budding period.” The budding period is from mid to late summer.
The expert then advised to stop fertilising once the plant starts to flower. She added: “Try not to overfertilise your hydrangea, otherwise it’ll burn its root system and cause a big stress for the plant, which may result in flower loss.
4. Improper watering
Hydrangeas are “water-thirsty” plants, so gardeners will need to water them one to two times weekly to keep the soil moderately wet, says Melvin.
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He warned: “Otherwise, the plant’s metabolic processes, necessary for growth and reproduction (flowering), are arrested because of water scarcity.
“It will also try to grow deeper roots in the search for more water underground instead of focusing its energy on the shoots.”
Nastya agreed hydrangeas are “moisture-loving” plants that don’t tolerate droughts, especially when grown in a pot. She recommended allowing the topsoil to dry between waterings and in warm and dry weather, gardeners should give their plant a drink once every three days.
When watering them the expert advised using at least 15 to 20 litres of settled water per one adult shrub. For potted plants, the amount of water should equal one third of the volume of the soil.
If hydrangeas are being grown in open ground, it’s best to mulch the soil around the bush, as it helps retain moisture and suppress weeds.
5. Not detecting pests
Pests are biological stresses to plants in general that prevent flower production. Melvin explained: “Some pests (root rot, aphids, and fungal diseases) take lots of the plant’s energy necessary for blooming.
“The hydrangea’s defense mechanism is switched on in the presence of pests, reducing its chance to bolt flowers.
“Detect the pests early with the regular inspection so that you can minimise the damage and increase your hydrangea’s flowering potential.”