Supplies for Successfully Sowing Cut Flower Seeds Indoors

Want to kickstart your gardening journey this year by growing your flowers from seed? I’m here to simplify the process by compiling a list of supplies you’ll need to start sowing your seeds indoors.

Living in the Pacific Northwest has taught me a thing or two about working with our quirky weather. That’s why I’m a huge fan of starting those delicate seeds indoors or in a greenhouse rather than planting them directly in the garden and risking damaging them.

Before diving into the world of seed starting, let’s make sure you’re equipped with all the tools for success. Whether you’re dreaming of a cutting garden bursting with flowers or planning the veggie patch of your dreams, getting your seedlings off to a strong start is crucial.

Ready to set up your seed-starting sanctuary? Let me walk you through everything you’ll need to grow healthy seedlings.

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What is Seed Starting and Why Does it Matter?

Seed starting is the process of growing plants from seeds indoors, giving them a head start before transplanting them into your garden when the weather warms up.

It’s essential for gardeners who want to grow their favorite flowers, herbs, or vegetables from scratch, especially in regions with shorter growing seasons.

By starting seeds indoors, you gain more control over your plants’ early growth, ensuring they have the right environment, light, and nutrients to thrive.

Seed starting allows you to grow a wider variety of plants, including unique or heirloom varieties that might not be available as seedlings at a local nursery or popular garden centers. It’s also a cost-effective and rewarding way to jumpstart your gardening season.

Where to Start Seeds Indoors

I start my seeds in a heated greenhouse, but there are plenty of other options for sowing seeds indoors.

You don’t need a fancy setup when starting seeds indoors. You just need a little creativity and a spot with the right conditions. The key is finding a place that stays warm, has good lighting, and is convenient for daily care.

Many gardeners use a sunny windowsill, a spare table, or even a shelving unit outfitted with grow lights. If natural light is limited, grow lights are a great option to ensure your seedlings get the light they need to grow strong and healthy.

Areas like basements, garages, or laundry rooms can be adapted into growing spaces as long as they stay above 65°F (18°C) and have room for trays, pots, and lights. Choosing a spot where seedlings won’t be disturbed by pets, drafts, or extreme temperature changes is also important.

Whether working with a dedicated growing rack or a small corner of your home, seed starting can be tailored to fit your space and lifestyle!

14 Best Seed Starting Supplies for Flower Gardeners

If this is your first year sowing seeds, having the right supplies can be a bit intimidating. I’m here to tell you that it doesn’t have to be.

Here are the indoor and greenhouse seed-starting supplies I use to grow my cut flower seedlings.

1. Quality Seeds

Using high-quality seeds is essential for growing a thriving cut flower garden.

They are more likely to produce vigorous, healthy plants that are more resistant to disease and pests and are better equipped to withstand harsh weather conditions.

Investing in quality seeds means your flowers will provide the following:

I used to buy my flower seeds from Floret Flowers, but they only offer a few of their own Floret Originals, including zinnias and celosia.

I’m trying seeds from different brands, such as Botanical Interests, Johnny’s Selected Seeds, Renee’s Garden, and Eden Brothers. Is there a brand that you like?

Cut Flowers That Thrive When Started from Seed Indoors

Many flowers thrive when started from seed indoors, especially those with longer growing seasons or delicate seedlings that need a controlled environment to get established.

Starting these flowers indoors gives them a head start to bloom earlier and more abundantly in your garden. Here are some top picks for flowers that do best with seed starting:

Starting these flowers indoors allows you to extend your growing season, experiment with unique or heirloom varieties, and enjoy earlier blooms in your garden.

Seed starting also helps ensure strong, healthy plants that can better resist pests and diseases once transplanted outdoors.

2. Seed Starting Mix

You may be asking “Is seed starting mix worth it?”

Yes, a seed starting mix is absolutely worth it if you’re serious about giving your seeds the best possible start. Unlike regular potting soil or garden soil, seed starting mix is specifically designed to meet the needs of delicate seeds and young seedlings.

Start your seeds with a high-quality seed-starting mix that contains nutrients and the proper pH balance.

Using regular potting soil is one of the mistakes beginning gardeners make when starting their cut flower garden from seed.

Look for seed-starting media that is free of toxic substances. Avoid anything containing synthetic fertilizer or bark, which can burn young plants. Find a seed-starting potting mix that holds moisture properly.

SHOP my favorite high-quality seed-starting mix.

3. Vermiculite

Vermiculite is a natural mineral often used in gardening and seed starting due to its excellent water retention, aeration, and soil conditioning properties.

It’s processed by heating to a high temperature, which causes it to expand into lightweight, spongy flakes that are perfect for improving plant growth conditions.

You can use vermiculite with a seed starting mix to plant seeds in containers.

After sowing the seeds, you can lightly cover them with a thin layer of vermiculite. Here are some of the benefits:

SHOP for vermiculite.

4. Seed Starting Containers

Choose the Right Container to Start Your Seeds

One of the most important seed-starting supplies is the container that holds the seeds. There are many options for choosing the right container for your seeds. You can start them in anything 2-3 inches deep that holds soil and has drainage holes.

What Can I Use as Seed Starter Trays?

There are many different sizes and shapes of containers and seedling trays to grow seedlings. Choose from a variety of seed-starting containers:

It’s crucial to have holes in the bottom of the container for a plant’s healthy root system. This system needs space to grow so that any water can drain. Otherwise, the water will sit in the container, and the plant will rot.

I get the best results with cell trays for most of my seeds. The 72-cell flats are my favorite because I never have to re-pot seedlings to a larger pot before it’s time to transplant them in the garden.

When planting sweet peas, pumpkins, or vines, I use larger containers, usually 4-inch pots. Root trainers are great for sweet peas, but I have seen a rolled-up newspaper tube work just as well. With so many choices, spending a lot of money on containers is unnecessary.

SHOP 72-cell flats.

Gardening Made Simple – Your Guide to Beginning Gardening

Clean Used Containers

If you reuse pots or containers, wash them with a one-part bleach / nine-part water solution to kill diseases or pathogens.

5. Drainage Plastic Trays

You will need a drainage or seedling tray to set the plant containers.

When the seeds are first planted, a bottom tray with water is filled, allowing the plants to soak up water through the bottom holes in the containers.

This watering method helps prevent overwatering and keeps the seeds from washing away if watering overhead. Continue bottom watering until the first leaves start to appear.

SHOP drainage/seedling tray.

6. Humidity Domes

A humidity dome lid provides a warm and moist environment for indoor seed starting, encouraging germination. I recommend using clear acrylic lids that fit snugly over the seed trays, flats, or pots.

SHOP humidity dome lid.

7. Heating Mats

A seedling heat mat can significantly enhance seed growth, especially in a greenhouse setting.

However, if you don’t have access to a greenhouse, you can achieve similar results by placing your seed trays on top of a radiator or refrigerator.

SHOP for a heat mat.

The concept here is to utilize bottom heat, which raises the soil temperature, giving your seeds a head start. This warmth accelerates germination and maintains an ideal, moist environment for the seeds to thrive quickly and healthily.

How Long Should I Keep Seedlings on a Heat Mat?

Seedlings should stay on a heat mat until they germinate, which is when you see the first signs of sprouting. For most seeds, this happens within 3–14 days, depending on the type of plant. Once the seedlings emerge, remove them from the heat mat to prevent overheating and promote sturdy growth.

After germination, move them to a well-lit area with consistent temperatures and ensure they have adequate airflow and light to continue developing.

What Seeds Should Not Be Started on a Heat Mat?

While many seeds benefit from the warmth of a heat mat, some plants prefer cooler conditions for germination. These seeds typically include cool-season crops and certain flowers like sweet peas, poppies, and larkspur.

8. Grow Lights

New seedlings need adequate light to grow healthy and strong, with around 14-16 hours of light. Without it, plants tend to become weak and spindly without enough light.

Heat lamps are recommended for growing seedlings, especially in the home or basement. They provide light and heat to encourage healthy, strong plants and help speed up growth.

SHOP for heat lamps and grow lights.

TIP: Depending on your indoor setup, you may want to purchase a plug strip for your mats and grow lights.

I started using grow lights in my greenhouse last year. In the past, I relied on the natural light from the skylights and windows in my outdoor structure, and my flowers have always thrived in my cut flower garden.

How Long Do You Leave Grow Lights on When Starting Seeds?

When starting seeds indoors, grow lights should be on for 12 to 16 hours per day to provide seedlings with enough light for healthy growth.

Seedlings require consistent, bright light to mimic the sun’s natural cycle and support photosynthesis. Insufficient light can cause seedlings to become leggy and weak as they stretch toward the light source. Providing 12–16 hours ensures they get the energy to grow strong and healthy.

9. Seed Starter Kits

If you plan to grow a small number of seeds, purchasing a seed starting kit is convenient and cost-effective. These kits typically bundle several essential components, such as a seed-starting tray, drainage tray, humidity dome, and grow light.

While you might find it more economical to buy these items separately if you’re sowing a variety of seeds as I do, the all-in-one seed starter kit offers simplicity and value for those who need just a few.

If you’re only buying a couple of kits, a pre-assembled seed starter kit is likely the best choice for ease of use and budget-friendliness.

Seed Starter Kits Available

• Seed Starter Tray with Light, 6PCS Seed Starter Kit with Grow Light, Seedling Starter Trays with Humidity Domes, Covers Height 3.9″, Indoor Gardening Plant Germination Trays (12 Cells per Tray)
• Seed Starter Tray, 40 Cells Seed Starter Kit with Seedling Heat Mat, Germination Tray with Humidity Control Domes, Cloning Kit, Propagation and Germination Station, Heat Mat for Plants Starter Kit
• Seed Starter Tray with Grow Light, 5 Pack Seed Starter Kit with Heat Mat, Seedling Starter Trays with Timing Controller Adjustable Brightness

10. Plant Labels or Tags

Label your seedling containers as soon as you sow your seeds. With a marker, write the name of the seed variety and the date you sowed the seeds on the plant tags.

This is one of the seed-starting supplies that often gets overlooked, but labeling plants is so important when growing seedlings and transplanting them outdoors for the growing season.

SHOP plant tags.

11. Table or Shelves

When sowing seeds indoors, the space you need depends on how many seeds you’re starting and your tools or setup.

Tables

A sturdy table is a popular choice for small to medium setups. Protect the surface with a plastic sheet or waterproof tray to catch spills and excess water.

Shelves

Multi-tiered shelving units are great for maximizing vertical space. Use adjustable grow lights on each level to ensure proper lighting for all trays.

Wire racks are lightweight, affordable, and provide excellent air movement around your trays.

Specialized Seed Starting Racks

These come with built-in lights and trays, making them a convenient all-in-one solution. Perfect if you’re starting a large number of seeds.

Countertops

Kitchen or laundry room counters can double as seed starting spaces, especially for small batches.

Folding Tables

Ideal for temporary setups. When the seed starting season is over, they can be easily stored away.

12. Temperature-Controlled Heater and Fan

Heater

A temperature-controlled heater in the greenhouse is important when planting seeds because it helps ensure that the temperature and humidity levels are optimal for them to germinate and grow.

Temperature and humidity fluctuations can delay or prevent seed germination, so having a heater that can maintain an ideal temperature is essential for successful seed planting.

I keep our greenhouse at a minimum of 45°F throughout the winter to grow seedlings and overwinter my geraniums.

SHOP temperature-controlled heater.

Fan

Having a temperature-controlled fan in the greenhouse when planting seeds is important because it helps to create a consistent and optimal environment for the seeds to germinate and grow.

SHOP HERE for the thermostat link.

The fan helps to regulate the temperature and promote good air circulation, providing a more even and consistent temperature throughout the day and night.

A fan also helps to reduce the risk of diseases, such as fungal diseases, from developing on the seedlings by reducing humidity and increasing air circulation.

13. Watering Can or Hose

Regularly water your seedlings in the greenhouse using a watering can or a hose. Until your seeds germinate and sprout, continue bottom watering so you do not wash the tiny seeds away.

14. Plant Journal/Planner

A garden planner or journal is one of the best tools for successful gardening. It’s not just a place to jot down notes—it’s your blueprint for a thriving, organized garden.

Keeping track of your gardening activities, observations, and plans can make all the difference in improving your results year after year.

Explore My Full Guide to Seed Starting

Here are some of the important posts from my ‘Growing a Cut Flower’ series to get you started:

For the entire series, click the button below.

Final Thoughts About Seed Starting Supplies for a Cut Flower Garden

If a gorgeous cut flower garden is your dream this year, set yourself up with the right seed-starting supplies essential for starting your garden seedlings indoors.

With the right supplies and a bit of patience, you can create a beautiful, productive cut flower garden that will provide you with a continuous source of fresh flowers through the summer and into fall.

If you have any questions or additional suggestions, please share them in the comments below. And be sure to share this blog post link with anyone who may find these gardening tips helpful.

Until next time,

Happy Gardening!

I’m a self-taught hobby gardener. Everything I share on my blog is my opinion and what has worked for me.

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