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Feb 20, 2013
Tips for growing Wave from seed
Lisa Lacy  Product Manager - Wave Petunias

One of the economical ways to fill your garden with Wave Petunias is to grow your own plants from seed. Many of our mail-order catalog partners sell Wave petunia seed packets, and you often can find unique colors you may not find in stores.

If you’ve never sowed your own petunias before, or haven’t had wild success, the tips below should be helpful. Follow these guidelines and soon you’ll be planting your seedlings and enjoying bright color in your garden.

When to start sowing
Your seed-starting time depends on the hardiness zone you live in. Hardiness zones determine your chance for frost – and frost will easily kill a young seedling. We generally suggest starting your Wave Petunias indoors about 10-12 weeks before the last chance of frost in your area. So once you determine that last frost date, count backwards those 10-12 weeks and you can plan to get started. What happens if you start too soon? Your seedlings may begin to stretch and out-grow their container, and could develop a weak structure since you won't be able to bring them outdoors in winter weather to harden them off (more on that below).

Sowing in seed trays
Once you've determined your start date, sow your Wave Petunia seed into a moistened germination media or potting soil. Petunias benefit from light for best germination, therefore do not cover the seeds. Place the tray in a warm and bright location.

Fluorescent lights are suitable for a light source, both for germination and for growing on. Place the fluorescent light approximately 3-6 inches (7-15 cm) above the top of the tray. The lights can remain on for 14-16 hours per day. A timer may be helpful to turn on/off the lights. And though light is important, you don’t want to place the tray in direct sunlight.

For tray temperature, you’re looking for 70-75 degrees F (21-23 degrees C) at the soil level for optimum germination.

The seed tray should be kept moist, not soaking wet or dry. Misting the tray with a clean spray bottle is the best method to water in this early stage, as this does not disturb the seed. Check your tray daily and water when the soil looks dry on top and the trays feel light. Do not allow the tray to completely dry out. Here’s a quick tip: Covering the tray with clear plastic may help maintain temperature and increase humidity.

After germination
Once germination occurs and small green leaves (called cotyledons) are visible, remove the plastic cover. These early first leaves emerge in about 5-12 days.

Keep your tray in the bright or fluorescent-lit area. The temperatures can start to cool, ranging from 65-70 degrees F (18-21 degrees C). Night temperatures can go down to 55 degrees F (12 degrees C). As the plants grow, and if you’re using fluorescent lights, move the light fixture up to maintain the 3-6 in. (7-15 cm) distance from top of plants. Once the young plants have between 4-6 sets of “true” leaves, it’s time to transplant them to individual pots or packs.

Finishing time
Keep the fluorescent lights over the young plants as described above and continue to monitor for moisture. While you don’t want the soil to completely dry out, you’ll want to wait to water until the soil is light brown and the container feels light when picked up. Then you can water thoroughly, allowing water to run through the bottom of the transplant pot or pack.

Now it’s time to feed your seedlings! Fertilize with a liquid feed weekly, following the instructions on the package. Soon your plants will be established with roots growing to the edge of the pot. To determine this, gently pull plants and soil away from the container to check for root growth.

Once your roots are strong, your plants can then be “hardened off.” Move the plants outside on sunny and warm days. Bringing them inside at night will help acclimate the plants will protect them from frost and prepare them for planting. During this step, be sure to maintain the water and fertilizer regime as described above.

Finally, after all your hard work of growing small seedlings into young plants, your new Wave petunias can be planted outside or in patio containers once any danger of frost has passed.

If you’re planning to start Wave petunias from seed this year, let us know! Comment below and share your seed-starting stories – successes and frustrations. And be sure to send photos of your seedling adventures to

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Reader Comments (39)

I find that bottom heat is important to get the seedlings to germinate. Instead of using the seeds in trays, I used a small amount of sterile seed starting mix in a plastic container, moistened and covered with plastic wrap with a few small holes, and a rubber band around the container edge. Then I floated this watertight container in my heated aquarium kept at a constant 76 degrees. Once the seedlings germinate, I then transplanted each tiny seedling into a "Red Solo Cup." All 30 seeds I planted grew into mature blossoming plants, and I didn't have to buy an expensive electric heat mat.
Wednesday, May 8, 2013 | Todd Sawn

I plan to harvest my petunia seeds this year, after buying many varieties at a massive expense but giving me a WOW factor, beautiful display that everyone has commented on. Just a little dead heading, watering and feeding once a week miracle grow plant food. Now all my friends neighbors and family want me to grow them in my new greenhouse for next year.

My plan is to start harvesting the seeds now until the 1st frost and then store the seeds ready to start sowing in flats, the end of Feb 2014. I plan to germinate on my new home made prorogation hot beds at 25 degrees c. (making a wooden frame, painted with furniture oil to water tight it and the sharp sand and heat wires with a thermostat)Then, once i can see the 4 leaves, i will transplant into 24s inserts, by which time i hope that the weather breaks or i'll have to turn on the blow air heating to maintain the temperature, whilst i start off the 2nd lot. then the plan is to put them in yet again another home made devise, a cold frame (an old gazebo using only a quarter of the frame, attached to the fence and then drape polythene down. i also purchased 3x 10 tire shoe racks 9.99 each, from off ebay, these will hold 60 flats in all) job done. i will keep them in here until they are strong enough to be planted out doors, rolling the polythene up on warmer days.

if what i plan to do is wrong or you think it wont work and i'm wasting my time!! will someone please say.

not sure if it's relevant but i live in the UK, Birmingham.
Saturday, September 7, 2013 | Green fingers Debbie

Thanks for the help described. For the first time, I've harvested seeds. Saw a youtube video to help with the harvesting of my purple Wave petunias, and got several envelopes of good seed. Also purchased proper germination trays with capillary mats, clear covers and raised trays to keep them out of standing water. This was my first year buying Wave plants because I'm cheap. We got a late start on our gardens, so by the time we shopped, the Waves were half price. We bought everything they had and now I'm spoiled for life. The Waves were effusive, hardy, easy and glorious. Next year, no more shopping for bedding plants. They'll all be Waves for a beautiful effect. Thanks again for the help!
Tuesday, October 22, 2013 | Karyn in Minnesota

I wish I had found this article a couple weeks ago! My starts are kinda leggy, about one inch tall, with only the first two leaves because my lights were way too far away! (about 16 inches)I have moved the lights closer, hoping that they may correct themselves since they're still really young.
Tuesday, April 1, 2014 | Nicole in Nebraska

I've been amazed at the germination success rate. I planted a 288 plug flat of purple wave petunias, another flat of Valentine double blossom petunias, and one more flat of Prism Sunshine Yellow petunias (which are strangely struggling more so than the others). Used jiffy seed starter for the plugs, then transferred to 72-pack/flats filled with miracle gro potting soil when ready. All of this is being done in my basement under two four foot fluorescent plant lighting and on heat pads. The only real point of concern I have is the moss or algae that seems to be growing on the surface of the potting soil???? (Too moist???). Not sure if it will ultimately hurt the plants or not. I had germination and transplant success at the following rates: 94%, 96%, 77% respectively, so this equates to over 750 plants! I also planted 200 marigolds and they seem to grow like weeds. Very easy. I am a little concerned about hardening the petunias, as I've had tragic results when attempting to start vegetables early indoors. This has been a lot of work and my first attempt at flowers from seed, so I hope the results are worth the labor. I've never seen wave petunias in person, only pictures. Thanks to this site for the tips and direction. I have relied on it for this effort. Happy planting!
Friday, April 18, 2014 | Scott, Utah

Thanks for the advice. My question is how long does it take from seed to get to the point of building hanging baskets.
Thursday, February 19, 2015 | Tim

One of the things i do is use plastic tooth picks to seperate the top of the soil from the bottom of the plastic covering. The reason for plastic is that wooden toothpicks tend to grow a fungus caused by the heat and moisture under the plastic cover. Another tip you might consider is the use of foam cups for starting seed. I purchase them in the dollar store. I punch some holes in their bottom and around the lower sides for drainage. Last year I grew about 400 plants from seed using the foam cups. When ready for transplanting, i remove the root ball from the foam cups. I wash the foam cups and will use them again this year.
Monday, March 2, 2015 | FRANK M

I have had trouble with the pelleted seed coating NOT dissolving when I plant my Tidal Wave seeds. I have tried a variety of different ideas...Still no luck. When the coating doesn't dissolve the seeds don't get ligh etc, and now you see my frustration. I have gone so far as to dissolve the seed coating off in a bowl and then searched for the seeds and then planted them. Sort of confounds me-and the ease of pelleted seeds is no longer there.
This problem started about 3 years ago when I noticed that the coating had changed colors. I LOVE my Tidal Waves, they hold up beautifully in the wind here at 5000' elevation.
Hope someone has another solution.
Sunday, March 15, 2015 | KD Suzuki

For your coated petunia seed, keeping the pellet moist until germination assures the pellet material dissolves. Try to use all the seed at one time because opening/closing the seed package multiple times can let in humidity. This can result in the pellet slightly absorbing the moisture from the air and then drying again. This results in a very hard pellet that can be difficult to breakdown. Purchase new seed, if possible, to compare the breaking down of the seeds. Let us know if you have any further questions. Thanks! ~Lisa
Tuesday, March 17, 2015 | Lisa, Wave Team Member

Maybe I lifted the cover too soon the last time I tried from seed. They died after germination. I had planted the seeds in those peat pellets. I'm trying again, this time in soil free starter material. I noticed when I lifted the plastic dome that they have germinated. Should I leave them under the dome until leaves have formed? That's what your directions say. I hate to have another failure.
Monday, March 30, 2015 | Erika

Hi Erika ... Starting from seed requires 3 important things: Warmth, Light, and Water. Leaving the plastic on holds in the warmth and humidity for those early stages. They're very delicate at that emerging stage. Make sure your growing conditions stay consistent for heat, and provide plenty of light once the true leaves start to emerge. Watering from the bottom is a way to ward off disease or saturation. Besides our tips above, our friends at W. Atlee Burpee have some helpful seed-starting at the following link:

Good luck!
Monday, March 30, 2015 | Katie, Wave Team Member

I find that planting in a flat tray, broadcasting the seeds and covering them with a light layer of soil, is a very easy and efficient way to go! You can then latter transplant them in individual pots or baskets. :)
Saturday, April 11, 2015 | Christine 14 yrs old

I started my great experiment with wave and tidal wave petunias this year. I didn't get them started until April 4 and the best place I had was my front bay window. I prayed a lot, and I read a lot and they are actually quite impressive now. I am getting ready to acclimate them outside for a few days, then I will put them in hanging baskets and flower beds. I can't wait to see them bloom!! Your articles have been very helpful!
Tuesday, May 5, 2015 | Rae Keefer

I started some purple wave petunias indoors, and grew them under lights. I put them out this may, and am waiting to see how soon they bloom. No buds yet, but the plants are a good size. They're about 6" tall and wide, with many leaves.
Monday, May 18, 2015 | Ma Martin

I started all kinds of wave Petunias in little grow pods in August and transplanted them into coconut fiber hanging baskets .They are starting to put out flowers .I live in North port Florida
Sunday, October 18, 2015 | Steve

How long does it take to get from seed to flower? I need an amount of time to best help me know when to expect the first flower to show up. I am starting a small greenhouse business.
Wednesday, February 3, 2016 | Rachel

Hi Rachel,
Wave Petunias have a general crop time of 10-12 weeks (from sowing to first bloom). If you're looking for complete greenhouse production information, please visit our horticultural parent company PanAmerican Seed. They have culture and growing advice for the Wave Petunia brand, as well as other seed-raised flowers and vegetables. Best wishes!
Thursday, February 4, 2016 | Katie, Wave Team Member

Hi I sowed purple wave pelleted seeds. Seedlings emerged with purple Cotyledons. Is that normal? In past, seedlings were consistently green. Any chance of seed mix up during packaging. Seeds are from McKenzie seeds in Canada.
Saturday, March 26, 2016 | Vish

Hi Vish! Thank you for your message. The cotyledons for Wave Petunias should be green, not purple. If you have concerns about a seed mix-up, definitely contact the mail-order company where you purchased your seed packets. You can send us a photo of the young seedlings at if you have any further questions. ~Katie, Wave Team Member
Monday, March 28, 2016 | Katie, Wave Team Member

Collected my seeds from my petunias in the fall. Planted them about 10 days ago. I love the fact that i started from scratch lol
What i would like to know is when do i clear them in order to have only one or 2 plants per little square
Wanted to post a picture but couldn't ??
Saturday, April 9, 2016 | Carolle Leclair

Hi Carolle ... Once your seedlings have their true leaves, you can separate them. If you've grown them in individual cells, you can continue to grow them until they have 4-6 mature leaves, then transplant them to their final container. If you'd like to send us photo you can email us at Good luck!
Sunday, April 10, 2016 | Wave Petunias

I never thought I could grow waves from seeds until a year ago when I had surgery on my hands and casts to contend with. Consequently, my railing planters were left out all winter. I live in S.W. Ontario. They call our area the "banana belt". Anyway, the following late spring when I could finally garden again I noticed all these little green leaves poking up in the planter on the south side of my house. Turns out they were waves that had seeded themselves and survived the winter outside!! This year I am going to try growing them indoors from the seeds I gathered last fall. Wish me luck!! LOL
Sunday, May 7, 2017 | Nancy Malach

I am planning start from seedling can I use a lot to g mix as seed starter. It's the Irish potting mix bordnamona brand .tips on how to start them.
Wednesday, June 21, 2017 | Radha

Hi Radha... We have not conducted any seed germination trials in peat-only substrates. However, if you're using something like Bord na Mona Growise John Innes Seed you should be able to achieve germination as it is identified for sowing and propagation.
Wednesday, June 21, 2017 | Lisa, Wave Team Member

When should we start these indoors? Our last frost date is usually around May 5.

Tuesday, February 6, 2018 | Dawn

Hi Dawn! With a frost-free date of early-May you'll want to start your Wave Petunia seeds indoors now through Feb. 20. This will give your seedlings plenty of time to grow and establish before transplanting to their larger containers.

Don't forget about the "hardened off" stage -- slowly adapting your young plants to the outdoors on warm, sunny days before finally planting them outside after all chance of frost has passed.
Wednesday, February 7, 2018 | Katie, Wave Team Member

About how long does it take for the true leaves to emerge? I have lots of seedlings, most of which germinated about 10 days ago. They all seem to be quite healthy and are growing towards the light (I turn the tray every day), but still only have the cotyledons.
Tuesday, March 13, 2018 | Tina

Hi, Tina! Thanks for your question. It may take another week for the first true leaves to develop on your seedlings. Depending on the soil temperature and light levels. Keep them relatively warm (70-75 degrees during these first stages) until their leaves appear.
Tuesday, March 13, 2018 | Katie, Wave Team Member

Yikes! I think I started my seeds too early. I started 120 wave petunia seeds on 2/9, last frost date is 4/21. I transplanted to solo plastic cups on 3/8. The roots are now coming out the bottom of the cups and some of them are even setting flower buds. I've been pinching off the flower buds (except for one). I don't have a greenhouse and still have them in the house under lights. I run a fan about 5-6 hours a day and have been opening up a window near them for a couple of hours a day. How long can I hold them at this stage? Do I need to repot (I would post a picture of roots, but can't figure out how to post a picture here)? I did not expect them to germinate and grow so well! I don't have room for 116 six inch pots under the lights. If I just move them to a south facing window, will growth slow or will they start getting too leggy? Any suggestions greatly appreciated!
Sunday, March 25, 2018 | Debbie Payton

Hi Debbie!
Removing flowers, cooling the plants and reducing the amount of light the plants receive should slow them down. If you're keeping the lights on 24hours a day, this is strongly contributing to the faster flowering of your Waves. If possible, reduce the light to only 10-12 hours; that should be sufficient.

As for re-potting: If the plants are very rooted, such as seeing mostly roots and not much soil, then repotting to a larger container is recommended. Good luck! ~Lisa, Wave Team Member
Monday, March 26, 2018 | Lisa, Wave Team Member

Didn’t know Wave now had seeds available. Will try to find them.
Wednesday, January 29, 2020 | Paul LaPrad

I'm trying to keep a very healthy garden for the bees. Do these pelleted seeds have any neonicotinoids in their coatings?
Wednesday, January 29, 2020 | Nancy

Hi Nancy,
No, our Wave Petunia and Cool Wave Pansy seeds do not contain any neonicotinoids. Thank you for your question!
Wednesday, January 29, 2020 | Wave Petunia Team Member

Just purchased seeds! Waiting on their arrival! Very excited!
Friday, May 15, 2020 | Joan Estes


I kept the seeds from my Hybrid Petunia Shockwave Coral crush flowers from last year. I sow them in january and they all came out. However, as I keep reading on the subject, it seems I cannot predict what the result will be. Can you help me with that?

Thanks a lot for your help!

Friday, March 19, 2021 | Elyse

Hi Elyse!
Thank you for being a Wave Fan. Since Wave Petunias are hybrid plants - crossed from two parent plants to get a specific offspring - the seed you saved from last year's plants will probably grow to look or act different. The fresh plants you purchase from stores are really one-of-a-kind. Any seed harvested could produce a different color OR it could not have the same vigor as last year's Waves. It's okay to experiment, of course, but for the best performance, we recommend starting with fresh Wave Petunia plants each Spring. Good luck!
Friday, March 19, 2021 | The Wave Team

I usually start my pelleted easy wave / wave seeds on a damp round coffee filter on top of 2 damp paper towel, inside an air tight transparent bakery container. (I wash the clay off the pelleted seed with a drop of water before placing it on the coffee filter) It is kept at room temp 75F under grow lights until they germinate. Once they have 2 leaves I gently lift them off the coffee filter (or the roots will cling into the paper towel) with a toothpick and place them into seedling soil trays. I find this method to be the quickest for germination.
Last year, I started the seeds in 72 plug trays only to loose them to gnat larvae. I really hate gnats. Some of the rootless seedling produced new roots when planted into new soil. New spring I will return to coffee filter paper towel germination.
This fall I took some petunia cuttings and they are now growing indoors, they will be used for more cuttings for spring plants. I can spend the money saved for more wave (color) seed .
Thursday, November 11, 2021 | Lorraine C

Hi, I am in Southern Alberta and started growing my own petunias last year. I use the plastic containers that you buy cookies in or that you buy food trays on. Just a few holes in the lid and they work fine. However this year I have not had the 'Tidal Wave' variety germinate, is there something different about that seed.
Your article is well written and informative, thanks, Myrna
Monday, April 17, 2023 | Myrna Young

Hi Myrna!
For Tidal Wave Petunias, they should germinate within 3-5 days if the soil, light and temperatures conditions are right. Make sure you are not covering the seed (Petunias benefit from access to light during germination). The soil temperature should be warm at 75 deg. F / 24 deg. C and the moisture of the soil should be high, especially if your seed is pelleted; it needs to be wet enough to begin breaking down the coating covering the seed. If there is still an issue seeing emergence, you can use a light sandpaper to gently rough the coated seed edge or soak in a wet paper towel overnight to push things ahead. We hope this helps and you get to enjoy masses of Tidal Wave Petunias!
Friday, April 21, 2023 | Katie, Wave Petunia Team Member