If you want indoor and outdoor plants to add a pop of color, petunias won’t disappoint you. These vibrant bloomers come in every color and multiple sizes, so you can pick the right type for your landscape design.
These plants are native to South America, and you can grow them in your home or garden by mimicking their optimal conditions.
I’ll teach you how to propagate petunias for the best results. So, let’s dive in.
Petunias can be grown in hanging baskets, containers, flower beds, and as trailing plants that spread in your garden.
Home gardeners can propagate petunias in two ways.
There are many petunia cultivars and hybrids that you can grow in your indoor and outdoor garden. Some of these hybrids are more popular than others.
Most home gardeners choose to propagate petunias from cuttings to grow a specific hybrid that can’t be easily found at nurseries.
The problem with petunia seeds is that they might not produce the same cultivar when you grow them because they come from hybrids.
Moreover, seeds take more time and effort to germinate and grow stems and blooms. As a result, it might be almost the end of summer before you can see colorful petunia blooms.
Stem cuttings can be kept indoors during the dormant season and planted outside or in a container when the time is right.
It’s essential to cut the stems at the right spot and keep them alive until it’s time to transplant them.
Here are the proper steps to prepare stem cuttings for planting.
- Check the petunias in your garden or indoor pots, and choose a healthy plant with compact growth.
- Choose the right stem to cut. A green and healthy stem can root easily, while old woody stems will probably fail to root.
- Trim off a healthy part of the plant, ensuring it’s at least six inches long and the bottom cut is just below a node. Use sterilized shears to keep the plant healthy.
- Remove the leaves from the bottom half of the plant and keep at least three sets of leaves on the stem.
- Dip the end of the stem cutting in a rooting hormone, and use a soft bristle brush to rub it on the nodes and cut the end.
- Prepare a soilless potting mix made of coconut coir, peat moss, and perlite and soak it. Let it drain for 15 minutes before transplanting your cuttings.
- Press the cuttings into the mix.
- Keep the cuttings in bright indirect sunlight and ensure the potting mix is always moist until you notice the first roots.
- Cover the container with sheer plastic and cut a hole in it to allow the water vapor to escape. Use wooden sticks to keep the plastic away from the leaves.
- Remove the bag for a few minutes each morning and mist your cuttings. Then, put it back on.
- Check the moisture of the potting mix and water it when it feels dry.
- Every few times, replace one watering with a diluted fertilizer solution. Keep the fertilizer diluted to one-eighth of its strength to avoid burning the cuttings.
- The roots take three to four weeks to become at least one inch long. This is when you can transplant them.
- Remove the plastic bag for longer periods every day to allow the cuttings to assimilate. This will enable the plant to get used to normal light conditions and temperatures without wilting.
- Choose a suitable petunia-specific potting mix and transplant the cuttings. You should only keep three cuttings in the pot to avoid overcrowding and competing for nutrients.
- Water the potting mix regularly and keep it in bright, indirect sunlight.
If you want to grow a new variety of petunias, you can grow these gorgeous plants from seeds. These plants should be started about 12 weeks before the last frost so you can transplant them at the right time.
You can either buy the seeds from a nursery or harvest them yourself to be able to grow them.
Buying them from a reputable source is crucial so they’re more resistant to diseases.
Seeds are fine and can be challenging to handle, so choose pelleted seeds if they’re available. The coating on them will dissolve over time, and they will be able to grow in your garden.
You can harvest seeds by keeping the spent blooms until they turn into seed capsules. Let them dry, and put the seeds in a container.
Keep this container in a cool, dry place.
Most people choose to start seeds indoors to protect them from the low temperatures. But if you live in a warm climate with long and mild springs, you can start them outdoors.
It’s crucial for the temperature to be over 60 degrees Fahrenheit and to provide the seeds with at least 12 hours of sunlight to allow them to germinate.
If you’re planting lots of seeds, you might need to buy a growing light system.
Here are the right steps to follow if you want to propagate petunias from seeds.
- Choose a suitable seed-starting mix and spread the petunia seeds on top of it.
- Moisten the potting mix.
- Gently press the seeds down into the mix, but don’t bury them.
- Cover the container with a transparent plastic sheet and keep it in a warm spot where it can receive at least 10 to 12 hours of bright indirect sunlight. Keeping the container away from bright sunlight is crucial as it might scorch the fragile seeds.
- The temperature must remain between 75 and 85 degrees Fahrenheit. You can use a heat mat to keep your seedlings warm if it’s too cold.
- The seeds will germinate and produce seedlings within ten days, depending on the climate. This is when you should remove the plastic sheet.
- At this point, you can thin out the seedlings, as you might have planted them too close to one another.
- Water them and keep them in bright, filtered sunlight. It’s crucial not to let the potting mix dry because petunias need consistent moisture, but it shouldn’t get soggy.
- Once the seedlings have three true leaves, you can start their hardening off stage. This is where you get the seedlings to assimilate to withstand the elements when you transplant them.
- Place your seedlings outside for two hours for a few days. Keep them away from drafts and intense sunlight.
- Gradually increase the outdoor exposure time.
- Fill a pot with a petunia-specific potting mix and transplant the seedlings. You can also pick a flower bed with well-draining soil to plant them in your backyard.
- Once transplanted, water your seedlings thoroughly to help the roots get established.
- Apply a slow-release fertilizer to help them grow.
You can propagate petunias in water successfully. Yet, you should always fertilize them regularly to provide them with the needed nutrients.
If you want to try this method, you’ll prepare the cuttings in the same previous way. It’s crucial to put them in water as soon as possible as they might be unable to root if kept without a nutrient medium.
Some varieties can root better, so if you notice that the roots aren’t growing, you should get new cuttings and start them in a soilless mix instead.
You should keep these cuttings in an opaque and dark container and add a little water when you notice it has evaporated.
Creating a greenhouse effect will benefit your cuttings, so use a plastic bag to cover the container and poke a hole for water evaporation. Use sticks to keep the bag away from the leaves.
With the help of a slow-release fertilizer, these cuttings can bloom. They might not be as grand as the ones you grow in organically rich soil, but they will still look amazing.
You can propagate petunias from cuttings if they’re already growing in your garden. This is a successful propagating method and can allow you to transplant them in the garden within weeks.
Cuttings should be dipped into a rooting hormone, and the new roots will appear within a month. After that, you can transplant them into a container or flower bed.
Starting petunias from seeds is more challenging, but it can also be successful if you follow the right steps.
If you can’t harvest good seeds, you should buy them from a reputable store.
I would personally recommend growing stem cuttings in a soilless mix or in water because, in most cases, seeds won’t be as successful. But if you’re growing a rare variety, this might be the only way available.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.