You can Grow Petunias from seed!

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Looking to add some beautiful petunias to your garden this year? Why not try growing petunias from seed? It can be a fun and rewarding experience, and it’s a great way to save money, too.

In this step-by-step guide, we will show you how to grow petunias from seed easily and successfully, this includes Wave Petunias. So get ready to plant some seeds and watch them grow!

• Sow Petunia Seeds
• Best Germination Conditions
• Petunia Seedling Care
• Transplant Petunia Plants
• Growing Petunias
• When to sow petunias seeds for early bloom
• At the end of this post is a video showing how I plant petunia seeds in trays and what they look like a few weeks later.

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Sow Petunia Seeds

You can sow your petunia seeds in trays, small containers, or soil blocks. When I am sowing a lot of seeds I like to use trays and then plant up the seedlings when they get big enough.

This works with all petunia varieties including wave petunias. Some are called Easy Wave and the name says it all!

Fill a tray or container with seed starting mix. It is easier to fill small individual seed starting containers with the dry mix and then set them into a tray of water to let it absorb and moisten.

No need to pre-wet before filling container, it is harder and messier to fill cell tray containers when the potting soil is wet.

Many petunia seeds come pelleted making them easier to handle. Plant the seeds about an inch apart or so.

If your seeds are pelleted do NOT cover with soil. The clay pellet coating is the cover. If you do not have a humidity dome then spritz the top of the soil daily to keep them moist.

If planting the petunia seeds in the trays with cells then plant one seed per cell. When using fresh seeds it is a waste to plant more than one plant per cell.

With the seeds I have purchased, I get great germination rates.

Press the seeds firmly into the seed starting medium. Petunias need light to germinate so no need to cover with soil.

Place the tray or container into another tray of warm water. Warm water absorbs more quickly into the seed starting medium. Let drain.

Related: See why I love Wave Petunias and how you can use them in your garden!

Petunia Seed Germination

Starting petunia seeds indoors is similar to other plants. Cover the plant trays to keep moisture in.

Place under lights and if you have one, a heat mat, specifically for seed starting. This aids germination.

Place the lights about 3 to 6 inches above the top of the tray. The lights should be on for 14 hours per day. The optimum temperature for good germination of petunia seeds is 70 to 75 degrees.

With a transparent cover over the seed tray to keep in moisture, you should not need to water. Expect germination in 5 to 12 days.

Remove cover.

Petunia Seedling Care

Keep the seedlings under the lights but remove them from the heat mat. Petunia seedlings will grow well in a lower temperature, 65 – 70F degrees. Nighttime temps can go down to 55F degrees.

As the petunia plants grow lift the lights to stay 3 to 6 inches above them.

Feed the seedlings weekly with a 50% dilution of a balanced organic liquid fertilizer. Agrothrive is my favorite and works wonders.

Keep watered, we want the soil damp not wet and we never want it to dry out completely.

Once you get attuned to seed starting you will begin to be able to measure if you need to water by feeling the weight of the tray of plants. They feel lighter when you lift them if they need water.

I also use a product called Organic Rev that seems to be really giving my seedlings a healthy boost.

I am testing more and more and will share my findings. Want to try it yourself? Get 5% off your order with the coupon code FlowerPatchRev

Transplant Petunia Plants

Once your petunia seedlings have 4 to 6 true leaves it is time to transplant them into larger pots or container packs.

If you are limited on space you can plant them into recycled 6 pack containers you may have saved. Or into 3 or 4 inches pots.

They will need to be kept in a relatively warm and frost-free area with plenty of light (for me that is on my seed starting rack) until it is safe to plant them outside or put into a cold frame.

When to Sow Petunia Seeds for Early Bloom

If you are wanting to get a head start on blooming with your petunia seed starting a good time is 10 weeks before your last frost date.

I start sooner but I have a greenhouse I can keep my many seedlings in before my last frost date. You choose.

Right now I have a petunia that seeded itself among my Geraniums I started from seed and it is blooming on my plant rack in the house in February. It is bringing me such delight!

Harden off your Seedlings

A week or two before it is time to plant your petunias out in the garden, it is time to harden them off or prepare them for outdoor conditions.

This takes a bit of work and patience. I don’t typically need to do this as I have mine out in the greenhouse and it is close enough to outdoor conditions.

You will want to slowly acclimate your petunia plants to the outdoors. Place the plants outside on a shaded porch or under dappled shade for a few hours a day and lengthen that time day by day.

Gradually get them used to direct sun before planting your petunias in the garden or in containers.

Read on the best care for petunias in the post linked.

Now for the video where I show you step by step how I start Petunias from seed.

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