Step-by-Step: How to Start Flower Seeds Indoors for a Beautiful Garden

March 02, 2023 1 Comment

Step-by-Step: How to Start Flower Seeds Indoors for a Beautiful Garden

Starting a flower garden from seed is fun and exciting! There is always something new to learn and discover when it comes to sowing flower seeds. In all that we do here on the farm, seed starting is the most magical and to boot - a high valued skill to have. In this blog post, we will guide you step by step through the process of sowing flower seeds and provide helpful tips for troubleshooting common problems.

Selecting the right seeds at Rooted Flowers.

Step 1: Choose the Right Seeds

Consider factors such as the size and habit of the flowers you are interested in growing and the time of year they will bloom. Refer to our blog post on How To Plan for Seed Starting Indoors to walk you through this initial step. 

Choosing the right container for seed starting at Rooted Flowers.

Step 2: Choose a Container

For a home gardener, a 32 celled tray is the best size for starting flowers. These trays are small enough to fit easily on a windowsill, but large enough to provide enough space for your seeds to grow and develop a nice rootball. For a very serious gardener or grower, consider starting seeds in a 72 celled tray or higher. To help you decide what works best for your growing space and conditions, check out Mastering the Art of Transplanting Flower Seedlings where we walk you through container sizing and space efficiencies. Download our container sizing guide here. 

Containers filled with potting soil at Rooted Flowers.

Step 3: Fill Your Container with Soil

Fill your containers with a good quality seed starting soil. This soil should be light and airy, allowing your seeds to easily germinate and grow. Make sure you gently pack the soil down, leaving a small indentation in the center of each cell where you will place your seeds. The soil does not need to be watered at this point. 

Sowing seeds at Rooted Flowers.

Step 4: Sow Your Seeds

Now it's time to sow your seeds! Simply place one or two seeds in the center of each cell, covering them with a light layer of soil. Oftentimes, we sow 2-3 seeds per cell. This guarantees something will sprout and we can always go back and pinch out the weaker plants. Make sure you label the type of flower you are growing, so you can keep track of which seeds are which.

Vermiculite on top of seedling trays at Rooted Flowers.

Pro tip! Instead of sprinkling a light layer of soil over your seeds, supplement with vermiculite. Vermiculite is a naturally occurring mineral that takes the form of shiny flakes. It is used to improve soil quality and give seedlings a helping hand. It’s naturally antimicrobial and will help to keep your seeds moist. If you have trouble with a green layer forming on top of your seeds, try using vermiculite. 

Bottom watering at Rooted Flowers.

Step 5: Water Your Seeds

Water your seeds gently, being careful not to disturb the soil. The best way to do this is by bottom watering. Make sure you water your seeds until the soil is evenly moist, but not soaking wet. Filling the tray that will hold the water so that there is a water line a third of the way up your tray. Then cover with a humidity dome or clear wrap — this ensures the seeds stay in a humid environment. You should not have to water again until you take your clear covering off. Take off the covering when 80% or more of your seedlings have sprouted.

Seedlings growing on in a warm location at Rooted Flowers.

Step 6: Place Your Container in a Warm Location

Place your seedlings in direct sunlight at a windowsill or under grow lights. The added benefit of bottom heat from a heat mat will improve your germination rate and uniformity. Not necessary but it will improve results. The room should be between 70-75°F or set your heat mat thermostat to 70F for most annual flowers. This will help your seeds germinate quickly and grow strong and healthy. Refer to our Bulletproof Seed Starting Station for inspiration and guidance. 

Seedlings sprouting at Rooted Flowers.

Step 7: Monitor Your Seeds

Check your seeds daily, making sure the soil remains moist but not soaking wet. If water is pooled at the bottom of your tray, that’s too much and drain it out. A layer of condensation should always be on the inside of your humidity dome or clear wrap. If you do not see condensation, they are too dry and you need to water. 

Troubleshooting Points:

  • Poor Germination: Poor germination can be caused by several factors, including planting the seeds too deep, not providing enough warmth, moisture, or light, or by using old or expired seeds. If you are experiencing poor germination, make sure you are following the steps outlined in this blog post carefully, and consider using fresh seeds for your next batch. Be sure to review the growing conditions such as light requirements or cold stratification.
  • Slow Growth: If your seedlings are growing slowly, this may be due to a lack of sunlight, warmth, or poor soil fertility. To resolve this issue, make sure your seedlings are receiving enough light, and consider using a high-quality fertilizer to improve the soil's fertility. You may also want to check the quality of the water you are using to water your seedlings, and consider using filtered or distilled water if necessary.
  • Disease: Diseases can be a common problem when growing from seed. To prevent these issues, make sure you are using a fresh seed starting mix, and avoid overwatering your seedlings. If you do experience disease, consider using an organic method to control the problem, or remove the affected seedlings and start over with fresh seeds. The most common problem is to develop algae on top of the soil from overwatering and poor air circulation.

Lots of seedlings at Rooted Flowers and an armful of celosia.

    Starting a flower garden from seed can be a fun and rewarding experience, but it does require patience, attention to detail, and a bit of know-how. By following the steps outlined in this blog post, you can be sure that your seedlings will have the best possible start in life, and will grow into strong and healthy flowers that will bring beauty and joy to your garden for years to come.



    Don't forget to check out our previous blog posts on indoor seed starting for even more information on starting a cut flower garden. 

    Starting Seeds Indoors: How to Build a Bulletproof Seed Starting Station

    How To Plan for Seed Starting Indoors 

    Mastering the Art of Transplanting Flower Seedlings

    1 Response

    Patti Kinney
    Patti Kinney

    October 09, 2023

    When my flower seeds start to grow and then do I need to do anything to make them spread out and thicker

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