Hydrangeas are easiest to propagate from cuttings, but you can also grow hydrangeas from seeds, only it takes much longer and it’s more difficult than propagating from cuttings.
There are multiple points of failure when it comes to propagating from seeds, but possibly the biggest downside is the amount of time it takes to grow hydrangeas from seed harvesting to mature plants that produce blooms.
If you’ve ordered hydrangea seeds off the internet or you want to experiment with growing hydrangeas from seeds, I’ll walk you through the propagation process and steps involved.
Harvesting Hydrangea Seeds
If you want to go through all the stages of propagating hydrangeas from seeds, you need to start with harvesting hydrangea seeds. This can be tricky, because hydrangea seeds are somewhat elusive due to their minuscule size.
Hydrangea seeds are produced by the plant’s enormous flowers, but don’t get fooled by the size of the florets, the seeds are actually very small, much like the size of crushed peppercorns.
To harvest, allow for the blooms to fade and dry. Depending on the variety this can take a couple of weeks. Once the blooms have faded, you can go ahead and remove them.
When deadheading hydrangeas, collect the flowers in a paper bag and allow for 3-7 more days to pass until they dry out completely.
Close the bag and shake well so that the seeds can fall out of the florets. Remove the blooms and empty the contents of the bag on a white sheet of paper.
Since the seeds are so tiny the white sheet of paper can help identify them more easily. The next step involves germinating the seeds, which is a simple and straightforward procedure.
Germinating Hydrangea Seeds
You can start the germination of the seeds after you harvest the seeds, but that leaves you with having to take care of hydrangea plantlets during fall and winter, and you may have trouble keeping them alive during this time.
In my experience, it’s best to start germination in late winter or early spring, which will leave you enough time to grow an almost established plant until winter sets in again.
Regardless of when you decide to germinate, the rules are the same:
- Fill a flat container with seed germination medium or other well draining potting medium and surface sow the seeds. Hydrangea seeds don’t need to be placed into the soil or mixed into the soil. Simply scatter them on the surface and water them.
- Keep the soil moist to promote germination
- You also need to keep seeding containers in a warm and sunny location
- Protect the seeds from cold drafts, wind, or cold temperatures
The seeds should germinate in about 14 days. You need to keep the soil moist, but not wet. Once the plantlets get large enough to be transplanted to their own pots, you should continue caring for them as you would normally care for hydrangea cuttings.
This means offering them adequate light exposure (dappled light or semi shade preferably), watering regularly to prevent them from drying out, and potting them in well draining soil.
It takes about 14 months for hydrangeas to grow from seed into an established enough plant. After 14 months, you can move the hydrangea plant to the ground.
Before moving it to the ground, make sure to account for factors such as light requirements and the height and width the plant will reach at maturity.
Pros & Cons of Seed Propagation
There are pros and cons to growing hydrangeas from seeds versus growing them from cuttings.
One of the reasons gardeners will attempt to grow hydrangeas from seeds is that the plants that will grow from the seed are considered new cultivars and not a clone of the hydrangea plants they’re sourced from.
Propagating from cuttings will create an exact clone of the hydrangea plant. So, if you’re after a new cultivar, propagate from seeds, if you want an exact copy of your hydrangea, propagate from stem cuttings.
Besides this point, there are a few other pros and cons of growing hydrangeas from seed instead of cuttings.
I must admit from the start that the cons of seed propagation simply outweigh the pros. I prefer propagating from stem cuttings simply because it’s easier. But that’s just me.
- You can harvest seeds and germinate them in fall or spring; however, cuttings should be harvested in spring when the plant’s metabolism is at its peak.
- You can experiment with different varieties by ordering seeds off the internet and germinating them yourself
- There is a certain amount of pride associated with cultivating hydrangeas from seeds, especially if you’re successful in your endeavor and get a blooming mature hydrangea
- If improperly stored seeds can become unviable and hence unable to germinate
- Seeds can be difficult to harvest and they’re not as widely available as stem cuttings
- It takes a lot of time for hydrangeas to grow into a mature plant when propagated from seeds. It’s easier and quicker to propagate from cuttings
- Even if the seeds germinate, they may not develop into mature plants as there are many factors that could cause failure including inadequate light, temperature fluctuations, improper watering
- Hydrangeas propagated from stem cuttings will bloom faster
All things considered, it’s so much easier to harvest stem cuttings and propagate hydrangeas from stem cuttings. Stem cuttings will root in a couple of weeks and they can be easily transplanted once the roots are established.
If you are curious to test seed propagation or you’ve put your hands on some seeds from interesting cultivars, you can follow the steps I described above and grow your hydrangea from seeds.
Getting the seeds to germinate is the somewhat easier part, getting the hydrangea plantlets to grow into established plants and produce blooms is the more difficult task.
It can take as much as two seasons for hydrangeas propagated from seeds to start blooming. Don’t be discouraged, however, with patience and a bit of time, you can enjoy hydrangeas grown from seeds.