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How to Grow Petunias from Seed

How to Grow Petunias from Seed

How to Grow Petunias from Seed

Originally from South America, petunias are a trumpet shaped flower and mostly grown as annuals in the US (although the can be perennials in zones 9-12). They are great for containers, borders, or bedding.

Why we love Petunias:

  • So MANY options! It is easy to find a petunia that works well with your planting needs.
  • VERSATILE! Easy to grow, resilient, and great for so many locations.
  • Great BLOOMERS that continue all summer!
  • They come in almost every COLOR! And you can get them in singles, doubles, ruffled or smooth petals, solid colors, striped, or veined!
Petunia seeds in gardener's hand.
Pelleted petunia seeds in gardener's hand.

Petunias seeds come in pelleted and non-pelleted varieties. Pelleted seeds are coated to create both a larger and more uniform seeds. Pelleted seeds are easier to space when planting, reducing the need to thin later, and can be used with a hand-held seeder. The coating easily dissolves in moisture.

Varieties:

Wave Series: This group is a spreading variety (about 4 feet wide) that blooms abundantly without the need to be trimmed back. It is tolerant of both heat and drought. 

Wave: The original Wave variety is good for hanging baskets, beds, and planters. It will overflow the edges, making a lovely cascade.
Tidal Wave: The Tidal Wave variety grows in hedge-like forms when planted close together. It will grow up supports, even though not a true vine. It is a great variety to try if you want a climbing petunia.
Easy Wave: The Easy Wave variations will grow like Wave series, but a bit more restrained and with less spread. They are ideal for hanging baskets.
Shock Wave: The Shock Wave series has smaller flowers but they produce longer and earlier than other Wave varieties. Not much deadheading is required as the flowers drop of on their own.

 

Multiflora Series: The Multiflora petunias are smaller overall but with more blooms. One major advantage to this variety is they are sturdier against wind and rain. They also require no deadheading.  Multiflora is a great choice for flower beds and containers and give them a try for your cutting garden.

 - Hurrah Mix

 

Growing Petunias from Seed:

  • Start inside 10-12 weeks before you plan to move them outside (after the last frost of your area and after hardening off).
    Gardener adding soil to planting tray for seedlings.
    Pouring pelleted petunia seeds into hand.
    Watering petunia seeds in a seedling tray with a spray bottle.
  • Flatten the surface of the soil and press lightly then water. We recommend the Coast of Maine Sprout Island and the 20 Row Seedling Flat.
  • Seedling tray with a propagation dome and garden labels.
  • Cover the trays with a Propagation Dome and keep them warm (70-85 degrees F soil temperature). A Heat Mat is a great way to keep the temperature up.
  • Light is very important for Petunias. They need at least 5 hours a day. Avoid direct sunlight but place them in a bright area. You can choose to use lights, like the Jump Start System, but be sure to keep them 4-6 inches above and move them up as the seedlings grow.
  • Green petunia seedlings starting to sprout in seedling tray.
  • Sprouts will come up in 7-10 days. Remove the cover at that point and move to a cooler place (60-65 degrees F soil temperature).
  • Once transplanted, water 1 inch per week if in the ground and more if in containers.
  • Fertilize once a month. Containers and double-flower varieties require additional fertilization for the optimal growing.
  • A good potting soil with fertilizing every 2 weeks is recommended for containers. Mixing in time release fertilizer, like the Down to Earth Rose and Flower Fertilizer Mix, will help keep them looking good. Do not let them dry out by keeping them well watered. The roots will fill up the container quickly.  
  • Removing dead blossoms (or deadheading) will help prolong blooming.

 

Green petunia seedling in gardener's hand.

Need help with seed starting? We wrote a blog post on it. Read it HERE.

Be sure to check out our full selection of Petunias. What is your favorite variety to grow?

2 comments on How to Grow Petunias from Seed

  • Pinetree Garden Seeds
    Pinetree Garden SeedsFebruary 04, 2019

    HI Byron! The petunia ancillaris is the parent to most varieties of petunias and probably what you remember. The Tidal Wave Silver smells amazing at night if you are looking for a good current day substitute.

  • Byron Shoemaker
    Byron ShoemakerFebruary 04, 2019

    Whatever happened to to the old fashioned petunias that emitted a pleasant fragrance on a warm summer night?

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