Starting flower indoors is one of the most rewarding things you can do when starting your gardening journey. There is something about watching the growth of a beautiful flower from seed germination to cutting that is just beautiful. 

Starting seeds indoors, specifically flowers can also save you lots of money! I have started seeds for my small cut flower garden in the past with success, but is my first year starting seeds for our potted flowers. I so excited about these guys. I harvest and saved the seeds from my nursery purchased white petunias to regrow the following year. 

I also decided to start overwintering geraniums in the fall so I can regrow them every year within repurchasing! Geraniums are perennials in some climates so with a few steps and care you can enjoy them year after year!

I’ve always wanted to do it, but never really had to push until just recently. As we all know the cost of every day expenses have increased, and apparently so has a petunia plant. I ended up paying $5.99 per petunia plant last year. Insane right?!

Top-down view of a seed starting tray with neatly arranged soil blocks beside a soil blocking tool on a wooden surface.

I was determined to not have to spend that money again so I made it my mission to harvest and save the seeds to regrow for free!

Why Start Flowers From Seeds?

Cost-Effective: Seeds are usually much cheaper than buying fully grown plants or seedlings from your local nursery or garden center, as I mentioned above! This is beneficial if you plan to grow a large number of flowers, or if you want to start saving money in general!

Variety and Selection: When you start from tiny seeds, you can have access to a wider variety of species than you might find in plant nurseries. Most nurseries only carry a few generic varieties every year. You will have better luck looking for seeds of unique flowers than you would young seedlings.

Better Adaptation: Seeds sown directly into your garden from your home may adapt better to the local soil and climate conditions than mass-produced greenhouse-grown plants.

When to Start Flower Seeds Indoors?

Always refer to the instructions on the back of your seed packet to see when you should be starting your flower seeds. They often provide specific information about when to start seeds indoors relative to your last expected frost date.

This date is important to determine when to start your seeds. In general, most seeds should be started 6-8 weeks before the last frost dates. However, this can vary and some flowers might need to be started earlier, while others can be started later.

It might seem a little complicated but it truly isn’t all you have to do is follow these steps to determine your region’s last frost date and find out when to plant each of your seed:

1. Type in your postal code into the Almanac frost dates. Look under the “Last Spring Frost” section on the table, that is your last frost date. Our last spring frost is May 29th. 

2. Now, check the back of you seed packet to determine how many weeks before your last spring frost you need to start your seeds. 

3. Lets pretend I want to start these King Size Apricot China Asters. By reading the back of the seed packet I can see that I can start them 6-8 weeks before our last frost date, or I can even sow them directly into the ground after our last frost. I probably don’t want to sow them directly into the ground since our growing season is short, and our first frost can come as soon as early September.

4. So to determine when I want to start these seeds I find my last frost date on the calender and count backwards 6-8 weeks. I like to choose the furthest date away to ensure I have strong seedling for transplanting. So in this case I will count back 8 weeks from May 29th. 

5. This takes me to April 3rd. You don’t have to be too specific on the date. Any day within that week or two works for your seed starting date.

To make your seed starting planner so much easier I have created this updated seed-starting planner. You can organize what seeds you want to start, when you need to start them, and even create a schedule for your seed starting! It’s free, all you need to to is sign up below with you email and I will send it directly to your inbox!

Glass jar on a wooden surface containing fine, dark flower seeds ready for planting, with gardening gloves to the side.

1. Choosing The Right Seeds For Your Garden

Choosing the right seeds for your garden involves considering a few factors to ensure the best growth and success of your garden.

Climate and Hardiness Zone: Understand your local climate and hardiness zone. This information helps in choosing plants that are suitable for your area’s temperature ranges and growing conditions.

Sunlight and Soil Conditions: Assess the sunlight and soil conditions in your garden. Some plants require full sun, while others thrive in partial shade or full shade. Also, consider the soil type (sandy, clay, loamy) and pH level, as different plants have different soil preferences.

Garden Space and Size: Consider the size of your garden and how much space each plant will need as it grows. This includes not just the space on the ground but also how tall and wide the plants will grow, which can affect sunlight for neighboring plants.

Growth Duration and Seasonality: Some plants are annuals (one growing season), while others are perennials (come back year after year). Choose based on how long you want the plants to occupy the space and the effort you’re willing to invest in replanting.

Purpose of the Garden: Determine the purpose of your garden. Are you growing flowers for aesthetic appeal, vegetables for consumption, or herbs for cooking? The purpose will significantly influence your choice of seeds.

Planting and Harvest Times: Check the planting and harvest times, especially for vegetables and herbs. You’ll want to ensure that your plants will reach maturity within your growing season. Our growing season is roughly 109 days so I want to look for flowers that will grow within that timeframe.

Seed Quality: Purchase seeds from reputable sources to ensure high germination rates and healthy plants. Check the packaging date – fresher seeds tend to have better germination rates.

Maintenance Requirements: Consider how much time and effort you can dedicate to garden maintenance. Some plants require more care, such as regular pruning or specific watering needs.

Pest and Disease Resistance: Look for varieties that are resistant to common pests and diseases in your area. This can reduce the need for chemical treatments and increase the success rate of your garden.

Seed starting tray filled with black soil blocks each with a small depression in the center for planting seeds.

2. Select Your Seedling Container

Choosing the right seed trays is important for the successful germination and growth of flower seeds to give them a positive head start. Here are are a few types of seedling containers, each with its own set of advantages:

  1. Plastic Trays and Pots: These are widely available and come in various sizes. They’re reusable, durable, and good for retaining moisture. However, they don’t allow for air pruning and can sometimes lead to root circling if seedlings are left too long before transplanting.
  2. Peat Pots: Peat pots are biodegradable and can be planted directly into the soil, which reduces transplant shock. They’re great for plants that don’t like to have their roots disturbed. However, they can dry out quickly and may mold in humid conditions.
  3. Coir Pots: Similar to peat pots, coir pots are made from coconut husks and are biodegradable. They are more sustainable than peat pots and also prevent transplant shock. They tend to hold moisture better than peat.
  4. Newspaper Pots: You can make these at home from newspaper, making them an economical and eco-friendly option. Like peat and coir pots, they can be planted directly into the garden, but they may not be as durable for longer growth periods.
  5. Fabric Pots: These allow for air pruning of roots, which promotes healthier root growth. They are reusable and promote good drainage, but they require more frequent watering as they allow more evaporation.
  6. Soil Blocks: Made using a soil blocker tool, these are blocks of compressed soil that hold their shape. This method eliminates containers altogether. Soil blocks reduce transplant shock and are eco-friendly, but they require a special tool and can be a bit messy.
  7. Cell Trays or Plug Trays: These trays have individual cells for each seedling, making them great for large-scale seed starting. They’re efficient for space and easy to organize. However, like plastic pots, they can cause root circling if plants are not transplanted in time.
  8. Egg Cartons: A DIY, biodegradable option that’s great for small seeds. However, they are not very deep, so they’re best for seedlings that will be transplanted early.
  9. Recycled Containers: You can use yogurt cups, milk cartons, or other household items. This is an eco-friendly and cost-effective option. Ensure they are clean and have drainage holes. Use a 1:20 bleach to water ratio solution for proper sanitation.
Hand holding a wooden soil blocker over a bin of moist potting mix, ready to make blocks for seed starting.

3. Prepare Your Seeding Soil

For starting seeds indoors, it’s important to use the right type of soil and prepare it properly to ensure the best environment for seed germination and early growth. Here’s how to go about it:

  1. Choose the Right Soil Medium: For seed starting, use a sterile, seed-starting mix or a lightweight potting mix. These mixes are designed to be light and fluffy, which helps with moisture retention and allows for easy root growth. They are also typically free of weed seeds and pathogens that could harm your seedlings.
  2. Avoid Garden Soil: Do not use regular garden soil for starting seeds indoors. It’s usually too heavy and may contain disease organisms or weed seeds.
  3. Pre-Moisten the Soil: Before filling your containers, moisten the seed-starting mix. It should be damp but not soggy. This initial moistening makes it easier for the soil to absorb water after the seeds are planted and provides the necessary moisture for seed germination. The best way to do this is to put your soil into a large container and slowly add water as you mix. Once the soil is saturated with water you will know it is ready when you can compress it with your hand like wet sand. As mentioned, it shouldn’t be soggy.
  4. Fill Containers Properly: Fill your seed-starting containers with the pre-moistened mix, leaving some space at the top. Avoid packing the soil down too hard, as this can make it difficult for the seedlings to push through the soil.

Tip: I like to add a tablespoon or two of ground cinnamon to the soil mixture. This can help reduce any mold or fungas within the growing medium, ensuring healthy growth and to avoid dampening off of you healthy transplants.

4. Sow Flower Seeds

Check the seed packet for specific planting instructions. Some seeds will need to be sown on the surface of the soil, as they require light to germinate, while others should be covered with a thin layer of soil. As a general rule, sow seeds at a depth approximately twice their diameter. For very small seeds, just press them gently into the soil surface. You can find all of the sowing information for your specific seeds on your own package of seeds. 

Always remember to label your seeds as soon as you sow them. Don’t wait!!  It is so easy to forget what you’ve planted where, so label each container with the name of the plant and the date of sowing. You can easily do this with a wooden popsicle stick and a permanent marker.

5. Place Seeds In a Warm & Sunny Location

Cover the Containers: If your seeds require darkness to germinate, cover the containers with a lid or a light layer of soil. For seeds needing light, leave the surface uncovered and place the containers in a well-lit area or under grow lights. 

Ensure Watered During Germination: Keep the soil moist but not waterlogged. Using a spray bottle to gently mist the soil can prevent disturbing the seeds. Alternatively, you can water from the bottom by placing containers in a tray of water, allowing the moisture to seep up through the drainage holes.

Provide Warmth: Most seeds need a consistent temperature of 65-75°F (18-24°C) to germinate effectively. A heat mat can be helpful to maintain a consistent soil temperature, especially for warmth-loving plants.

Ensure Adequate Lighting: Once seeds sprout, they need plenty of light to grow strong and healthy. Place them in a sunny window or use artificial grow lights, keeping the lights on for about 14-16 hours per day.

Thin Seedlings if Necessary: Once your seedlings develop their first true leaves (the second set of leaves), thin them out if they’re too crowded. This ensures that the remaining seedlings have enough space and resources to grow.

Transplant Seedlings When Ready: When seedlings are large enough to handle and have developed a few sets of true leaves, they can be transplanted into larger pots if necessary before eventually moving them outdoors.

Wooden plant markers labeled 'N. Petunia' inserted into soil blocks in a seed starting tray, indicating plant varieties.

6. Monitor & Maintain Seedling Growth

Water Wisely: Overwatering can lead to fungal diseases, while underwatering can stress plants. Water when the topsoil feels dry. Use a watering can with a fine spray to avoid disturbing the soil or damaging the fragile seedlings. Bottom watering is also a good method, where you place the containers in a tray of water and allow the soil to absorb moisture from below.

Fertilize Carefully: Once seedlings have a few sets of true leaves, start fertilizing with a half-strength, balanced natural liquid fertilizer every two weeks. Avoid over-fertilizing, which can harm the plants.

Ensure Good Air Circulation: Good air circulation helps prevent disease and strengthens plant stems. A gentle fan set on low and directed away from the plants can provide sufficient air movement.

Harden Off Seedlings: Gradually acclimate your seedlings to outdoor conditions over 7-10 days before planting them in your garden. This process, known as hardening off, involves taking the plants outside for a few hours each day, gradually increasing their exposure to sunlight, wind, and outside temperatures.

Transplant at the Right Time: Wait until after the last frost date to transplant your seedlings outside. Also, consider the weather conditions; a calm, cloudy day is ideal for transplanting to reduce stress on the plants.

Growing anything for the first time from seed can be overwhelming but exciting! You don’t need to be a seasoned gardener to start you own beautiful flowers from seed. You just need to try and be willing to learn and sometimes even fail! The key is to just have an open mind, educate yourself and just start!

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