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Each Hydrangea plant grown from a seed is unique, it’s not a copy of the parent plant as they don’t grow true to seed. If you want to grow the same variety of Hydrangea then you would need to take cuttings instead.
However, only Hydrangeas that produce fertile seeds can be grown from seed; you need to grow those that produce sterile seeds also from cuttings. Be aware that, while an exciting exercise, growing Hydrangeas to the blooming stage from seeds takes a long time – several years in fact.
Where to collect Hydrangea seeds?
You can buy hydrangea seeds or you can collect them yourself from an existing Hydrangea shrub in your garden.
- You need to wait for an extra two to three months after the flowers has finshed on the plant before you remove it from the Hydrangea bush. They will be brown and dry once they are ready to remove. Deadhead the old bloom carefully as there may be new buds already on the branch.
- Collect several of the finished flowers and put each one in a separate paper bag to dry.
- Put the bags somewhere warm and dry to let the seeds dry out for anywhere from three days to a week or more. If the flowers are shrivelled and brown then they’re dry.
- Close the bag tightly and shake it to loosen the seeds from the flowers.
- Tip the bag contents out onto a white piece of paper and gently shift everything around until you find the seeds. The seeds are very small and it may take some looking to find them among all the dry flower debris.
When to sow Hydrangea seeds?
You can choose to sow the seeds when they’ve dried enough around autumn or you can store them in a paper bag in a cool place until spring.
Germinating the seeds in the autumn and winter gives you the extra task of taking care of the small plants through the winter but it does start the process several months earlier than waiting till spring.
How to sow and germinate the Hydrangea seeds?
- Fill a small seed tray with seed compost, you could also just use a multi-purpose compost. Make sure that it drains well.
- Sow the seeds on the surface. Its important to note that Hydrangea seeds don’t always germinate well if they’re buried under or mixed into the soil.
- Water the seeds carefully or leave the pot to soak in water for around 20 minutes until the compost has obsorbed the water.
- Put the container in a warm, sunny and protected location such as a sunny windowsil or greenhouse. Using a propagator can help speed the process up and germination can also be more reliable.
- Keep the soil moist but not water logged.
- Inspect the seeds regularly; after around 14 days the seedlings should start to germinate and a few weeks later they may be large enough to pot on into a smaller pot something around 9cm and grown on.
What else to know?
It takes about 14 months from planting the seed to when the hydrangea plant is strong and big enough to transplant into the ground in your garden so be patient.
Seeds stored over the winter for propagating in the spring may not germinate if they’re not kept in the right conditions. Once dry, cool dry conditions are best.
Your Hydrangea plant grown from seed may not bloom in its first few growing seasons; or it may bloom the first year and then not for one or two after that. The plant takes time and energy to establish itself before putting its effort into producing flowers.
You’re not guaranteed that the plant that results from the seed looks the same as the parent plant – and that’s what’s exciting about this process. Propagating plants from a cutting is the only way to guarantee an identical copy of the original plant, but anything can happen in a plant’s seed production to change its DNA.
Overall, growing Hydrangeas from seed takes a long time, however, it can be a fun way to grow Hydrangeas as you never know what you’re going to get.