Whether you’re new to gardening or a seasoned pro, starting seeds indoors can be rewarding and a cost-effective way to grow your own food and flowers. Millions of gardeners start their garden seeds indoors, meaning there are many, many opinions of what works best. To start, every gardener needs some guidance and general thoughts and ideas.
Ultimately, there is no one right way to start your garden seeds indoors. The more you read, the more confusing it can become. Don’t let this slow you down; get basic supplies and plant seeds in the soil. Growing your garden from seed is fun and extremely satisfying. In this guide to starting seeds indoors, I’ll walk you through things you need to know and think about to start seeds indoors successfully.
As I see us getting to the end of winter, I start dreaming of my garden. I start thinking about what I will grow more and some things I will grow less of. As gardeners, we are always learning from our previous years’ gardens, and I have a lot more to learn!!
Corn is one of these things I need to learn more about; I have not had a good crop yet! Even though I like having corn stocks for fall decoration, my main reason is to eat my sweet, homegrown corn, which I have yet to do! I will try again with a different variety this year and see what happens.
Therefore, as the gardening season approaches, many gardeners and homesteaders are eager to get a head start on their plants by starting seeds indoors. Purchasing your seed packets is just the first step.
An Easy Guide For Starting Garden Seeds Indoors
Choosing the right seeds for starting seeds indoors.
It is important to pick the seeds that will grow in your area by the length of your growing season and the garden zone you live in.
In my shorter growing season and without a greenhouse, I cannot grow every tomato I want. I have approximately 119 days to grow my warm-weather crops, so choosing tomato seeds that need 110 from the transplant date just does not work. My San Marzanos take 80-90 Days to mature from the time I transplant them in the ground.
Once your seedlings are in the ground, the most frustrating thing that can happen is a plant full of leaves and zero fruit — here’s why that happens and how to fix it.
Every year as September comes around, I look at my San Marzanos that I grow for canning and wonder if they will ripen before my last frost date. Some do, but a large quantity don’t, which means that my husband and I are picking the last green tomatoes to ripen indoors. Therefore, I am growing varieties such as Early Girls, which take about 60 days to mature. I am always on the lookout for varieties new to me, such as Sub Artic Plenty that I am going to try this year that promise even a shorter growing time. You will not find these varieties at your local garden center as plant starts or even in the seed packets they sell. The only way to grow these uncommon varieties is to plant your own seeds that you order by mail online. For a few years, I have used seeds from Baker Creek Heirloom Rare Seeds and True Leaf Market Seeds & Supplies. I have had great results with the seeds I have purchased from them and love the varieties I can get from them.
Why would you start seeds indoors versus the direct sowing of seeds outdoors?
Control Over Growing Conditions:
One of the biggest advantages of starting garden seeds indoors is the ability to control the growing conditions for your plants. By starting seeds indoors, you can provide ideal temperature, light, and moisture levels that may not be achievable outdoors. This control allows you to create the perfect environment for germination and early growth, giving your plants a strong start before they are transplanted outside.
Extended Growing Season:
Growing garden seeds indoors can also significantly extend your growing season. By starting seeds early indoors, you can get a jumpstart on the growing process and have larger, more established plants ready for transplanting once the weather warms up. This extended growing season can lead to earlier harvests and an overall longer period to enjoy your garden produce.
Protection from Pests and Disease:
When you start garden seeds indoors, you can protect your young plants from pests and diseases that may be present in outdoor soil. Keeping your seedlings inside until they are strong enough to withstand these threats can reduce the risk of losing plants to common garden pests and diseases. This added protection can help ensure a higher success rate for your seedlings.
Variety Selection:
Starting garden seeds indoors also opens up a world of possibilities when it comes to plant variety selection. By starting seeds yourself, you have access to a wider range of plant varieties that may not be available as established plants at local nurseries or garden centers. This allows you to experiment with unique or heirloom varieties that can add diversity and interest to your garden.
Cost Savings:
Finally, starting garden seeds indoors can save you money in the long run. While there may be upfront costs associated with purchasing seed-starting supplies such as trays, pots, and grow lights, these investments can pay off over time as you grow your own plants from seed rather than purchasing established plants each year. This cost savings can add up quickly, especially for avid gardeners who like to grow a wide variety of plants.
Crops that should be sown directly into the garden.
Some crops do not fare well if started indoors and being transferred to the garden, they do better if sown directly. Most root vegetables fall into this category. See the list below for the most common things that should be sown directly.
Carrots:
Carrot seeds are tiny and delicate, making them difficult to transplant once they have sprouted. It’s best to sow the seeds directly into well-prepared soil to ensure straight and healthy carrots.
Radishes:
Radishes are known for their quick growth and easy cultivation. Sow radish seeds directly into the ground for a fast and flavorful harvest.
Beans:
Beans thrive in warm soil and do not respond well to transplanting. Sow bean seeds directly into the ground after all danger of frost has passed for a plentiful harvest.
Corn:
Corn is a staple in many home gardens, but it does not transplant well due to its sensitive root system. Sow corn seeds directly into warm soil in full sun for optimal growth.
Sunflowers:
Sunflowers are a favorite among gardeners for their cheerful blooms and tall stature. Sow sunflower seeds directly into the ground in late spring for stunning summer flowers.
Peas:
Peas prefer cool weather and do not tolerate root disturbance well. Sow pea seeds directly into the ground as soon as the soil can be worked for sweet and tender peas.
Beets:
Beets are best grown from seed sown directly into the ground as they do not like to be transplanted. Sow beet seeds in loose, well-drained soil for delicious roots.
Squash:
Squash plants have large roots that can easily become damaged during transplanting. Sow squash seeds directly into warm soil after all danger of frost has passed for an abundant harvest.
Melons:
Melons require warm soil and ample space to spread out their vines. Sow melon seeds directly into well-drained soil with plenty of sunlight for juicy fruits all summer long.
Leafy greens:
Leafy greens such as lettuce and spinach like colder weather and also do not do well when transplanting.
Zinnias, Cosmos, Marigolds, and other flowers:
Flowers are beloved for their bright colors and long-lasting blooms. Sow many flower seeds directly into the ground after all danger of frost has passed for vibrant flowers throughout the season.
Herbs:
Many herbs grow easily and fast by seed such as basil, thyme and others. Sow these seeds into the ground after the last frost date has passed.
Knowing your frost dates for starting seeds indoors
If you live in a cold climate like I do, starting seeds is needed unless you purchase all your garden starts from a nursery. This can get very expensive but also limits the varieties you can grow. My last frost date is May 19th. In my area, the first fall frost date is September 19; this gives me 119 days of growing season. The old timers in our area always say don’t plant your garden until the snow is off Rathdrum mountain. I have found this wisdom to be true.
Starting seeds indoors is a must for a long enough growing season
So, when choosing seeds, I need to be able to grow my crop within 119 days. With such a short growing season, I am very cautious when transplanting my 50+ tomato plants.
Even though my last frost date is May 19th, a couple of years ago, on June 3rd, I came home to a snow/graupel storm. If you are unfamiliar with graupel, it is a soft type of hail or snow pellets. I had just planted my tomato plants that I had been tending to in my house for 8 weeks!! I was almost in tears thinking about all my newly planted being beaten to death by this little storm. When I got home and ran to my garden, I found my new seedlings badly beaten. Luckily, most of them survived.
This is a cautious tale about last spring frost and first fall frost dates. These frost dates are based on past years’ averages. Since then, I have purchased garden frost cloth, also known as garden blankets, from Amazon – for those surprise late or early frost or snow surprises. I watch the weather reports carefully during these times of the year, but unpredicted weather does happen. It is also important to remember that in the spring, your garden soil temperature will be colder than your outdoor air temperature.
Here is the link to get the last frost date for your area by zip code. Almanac.com
Before you plant, it’s worth knowing if your seeds are still viable — here’s how to test seed germination and viability before you waste a whole tray.
Garden zones
Garden zones, also known as hardiness zones, are defined areas that categorize the Earth’s climates to help gardeners understand where plants can grow based on minimum winter temperatures. Knowing your zone can guide you in selecting the right plants that will thrive in your local climate conditions. This is important when planting fruit trees and bushes. Since I live in Zone 4, I have to be very cautious about which variety of fruit trees and berry bushes I choose so they can survive our winters.
When should you start your seeds?
Reading the seed packet is the best place to find out when to begin your seed indoors. 10-12 weeks before your last frost date is the longest time I have seen to start seeds indoors. Most seeds seem to fall in the 6-8 weeks before the last frost date. Again, here is a great link to find out your last frost date. Once you know your last frost date, just look at your calendar and count the weeks backward. I keep a copy of my seed sowing calendar with all planting dates marked down. That way, I am ready every spring and don’t have to do the work again.
It is not a good idea to start your seeds too early, they will just become leggy. Again, read the back of your seed packet for how early to start the seeds and other important information, such as how deep to plant seeds, etc.
Choose the right containers for starting seeds indoors:
When starting seeds indoors, there are many choices as to what is the right container to use. Here are some of them.
Peat Pots
Peat pots are made out of peat moss and wood products. The good news is that they are biodegradable and are, therefore, good for the environment. The bad news is that they can start to deteriorate, especially on seeds that need a long time to grow, such as 10-12 weeks. They absorb water, taking it away from the soil. For that reason, I don’t like to use them.
Peat pellets
Peat Pellets are made out of compressed peat moss wrapped in a biodegradable netting. They are small pods that expand about 7 times when water is added. I don’t like using them since they are made out of peat, which has a tendency to dry out quickly. I occasionally still find the pellet netting in my garden and wonder how long they actually take to biodegrade. The last reason I don’t like them is that the pods are very small, which requires me to transplant my starts quickly.
Toilet paper rolls
I have seen where gardeners have started their seeds in the toilet paper cardboard rolls. After having trouble with peat pots falling apart, I imagine these would also do the same. For that reason, I have not used them.
Eggshells
Many use eggshells, which seems like a good idea. I already put ground eggshells in my garden. I have not tried them because they are small, and they don’t have a drain hole, making me concerned about over-watering my tiny seeds. The last reason is that I cannot see the roots therefore making it harder to monitor if they have outgrown their space.
Egg cartons – cardboard and plastic
Cardboard egg cartons also seem to deteriorate quickly.
Now, that brings me to clear plastic egg cartons. This is the first year that I am actually going to give these a try. I will poke small drainage holes in each egg holder so they drain well. I like seeing the roots and knowing when to transplant them. Finally, I like the idea that I can close the lid, and since they are made of clear plastic, they become a dome to help keep the seeds warm and the soil from drying out too quickly. This will give my seeds a good start. Once the seeds have sprouted, I will leave the egg carton lid open. For more on that reason, see the section below on how to prevent damping off disease.
Soil Blocks
Garden soil blocks are essentially a way to start seeds without using traditional pots or trays. Instead of planting seeds in individual containers, gardeners use a special tool to create compact blocks of soil that serve as the seed starting medium. These blocks can then be transplanted directly into the ground without disturbing the roots of the seedlings.
One of the main advantages of using garden soil blocks is that they promote healthier root growth. Because the roots are not confined to a small container, they are able to grow freely and develop a strong root system. This can lead to stronger, more resilient plants better equipped to withstand outdoor stressors such as pests or droughts.
Another benefit of using garden soil blocks is that they are said to reduce transplant shock. Additionally, garden soil blocks are more environmentally friendly than plastic pots or trays.
However, there are some drawbacks to using garden soil blocks as well. One potential downside is that they can be time-consuming to make, especially if you have a large number of seeds to start. Creating each block individually takes more effort than simply filling up trays with potting mix. Additionally, if not properly watered and cared for, soil blocks can dry out quickly due to their smaller size. I have not used these before, but I want to try making soil blocks next year.
Recycled containers
I am all for recycled plastic containers from Solo drinking cups, yogurt containers, 4-6 inch plastic garden containers, and seed starting trays.
The drinking cups and yogurt containers are a little larger, so I don’t have to worry too early about the roots getting too crowded. I make sure to poke a hole in the bottom of these containers to make sure of proper drainage. Seed starting trays have good sized drain holes,and I have reused these trays many years in a row. The drain holes allow not only good drainage, but I can monitor to see if roots are starting to grow out of the bottom indicating that it is time to replant into a larger container.
Anytime I do purchase a garden plant from a garden store, I keep the container for transplanting my own seedlings into when they have outgrown their small container. It is a good practice to clean and sanitize all recycled containers – see more below on how to Prevent damping off disease.
Seed starting trays
This brings me to the starting trays. I have found to like the rectangle shape of them, allowing me to start my seeds in as little amount of space as possible.
Currently, I grow all my seeds in my living room by a south-facing sliding door along with LED growing lights that are also close to our wood stove for heat. This is not my ideal situation, but this will have to do until my office gets done in the barn we are building. I will then have more space to spread out. I also like that I can reuse the starting trays for multiple years. Of course, my concern with plastic starting trays and recycled containers is that they are made of plastic. I don’t love using plastic. Not only for the environment but also for the potential of the plastic materials leaching into the soil mix. Ugh! What to do??? I will try the soil blocks next year, they sound promising.
The best container is the one that works for your space, your budget, and your level of patience. Start simple and adjust as you go.
Want perfectly spaced seedlings without the thinning headache? DIY Seed Tape solves that problem before you even start.
Let’s go over Damping Off Disease what it is and how to prevent it when starting seeds indoors.
Damping off disease is a fungal infection that primarily affects young seedlings. It can be caused by various types of fungi, including Rhizoctonia, Pythium, and Fusarium. The disease typically attacks the stem of the seedling at or near the soil line, causing it to become weak and eventually collapse. This can happen quickly, sometimes within just a few days of the initial infection.
One of the symptoms of damping off disease is the sudden wilting and collapse of seemingly healthy seedlings. You may also notice discolored or mushy spots on the stems of affected plants. In severe cases, you may even see a fuzzy mold growing on the surface of the soil. It’s important to act quickly if you suspect damping off disease is affecting your seedlings to prevent further spread.
To prevent damping off disease in your seedlings, there are several measures you can take.
First, ensure that your gardening tools and containers are clean and free from fungal spores that could cause infection. Use sterile potting mix when planting seeds and avoid overwatering, as excess moisture can create an ideal environment for fungal growth.
Another effective way to prevent damping off disease is to provide good air circulation around your seedlings. Avoid overcrowding them in trays or pots, as this can increase humidity levels promoting fungal growth. Use a fan or open windows to ensure proper ventilation in your growing area if possible.
Lastly, consider using natural fungicides such as neem oil to help protect your seedlings from fungal infections. Organic methods can be effective at preventing damping off disease without introducing harmful chemicals into your garden.
Understanding damping off disease in seedlings is crucial for every gardener who wants to grow healthy plants from seeds successfully. By being vigilant about cleanliness, proper watering techniques, air circulation, and natural fungicides, you can greatly reduce the risk of this common fungal infection affecting your precious seedlings.
To Prevent damping off disease:
Clean and sterilize your recycled containers
Ensure your recycled containers are clean and sterilized before adding soil to prevent diseases from affecting your seedlings. Here is how to do it.
Wash your planting trays with soap and water. Let them dry, and then spray everything with hydrogen peroxide (or deluded bleach); let sit for 20-30 minutes, and then rinse with clean water.
New quality soil to prevent damping off disease
Use quality seed starting mix: It’s essential to use a high-quality seed starting mix when starting seeds indoors. To prevent the spreading of diseases and any bacteria, do not reuse old soil. Regular potting soil is too dense and may not provide the proper drainage that seeds need to germinate successfully. Use new seed-starting mixes designed for seed germination. We use Purple Cow Organics products on our garlic farm, which I love and trust. I like to use Purple Cow Organics All Natural Seed Starter Mix, which I purchase through Amazon.com
Any high-quality seed starter mix works. Some gardeners like making their own, but I like the soil mixture I use from Purple Cow Organics and have not done this.
Provide adequate light
Light is crucial for seedlings to grow strong and healthy. Place your seed trays near a sunny window for direct sunlight, or invest in a grow light if natural light is limited. Most of the time, especially where we live, the late winter/early spring weather can be dreary, so just a sunny window may not be enough, and I needed to add artificial light. I use LED lights for my plants. Keep the lights on for 14-16 hours a day, adjusting the height as the seedlings grow taller. The light can be basic fluorescent lights or newer LED grow lights. Either will work.
Maintain consistent moisture levels
Keeping the soil moist but not waterlogged is key to successful seed germination. Use a spray bottle or watering can with a fine mist setting to avoid disturbing delicate seedlings by giving them too much water. Covering your trays with plastic domes or clear plastic wrap can help retain moisture until the seeds sprout. After they sprout, the plastic dome covers should be removed to provide good air circulation.
Proper air circulation
Good air circulation is important to prevent damping off disease. This can be done by running a small fan over the seedlings to make sure you have healthier plants. If you have a warmer sunny day, open the window for a while. You can also just run your hand lightly over the plants. Doing this helps prevent damping off disease, and the movement helps grow strong plants.
The ideal temperature for growing seedlings
The optimum temperature for growing seedlings is 70-75 degrees Fahrenheit. Since I have my seed trays near the wood stove and I like the house temperature to be pretty warm, this is usually no problem. If your house is cooler or you grow your seedlings in a colder space, such as a basement, then it is a good idea to place a heat mat under your growing trays.
Fertilizing your seedlings
Your seedlings should get fertilized when they are about 3 inches tall after they get their second set of leaves, also known as true leaves. Fertilize them with a good quality fertilizer, preferably organic. The fertilizer should be mixed at half the recommended rate and applied once or twice a week.
When to transplant seedlings into larger containers
Size of Seedlings: One of the first things to consider when deciding if your seedlings are ready for larger containers is their size. As a general rule of thumb, seedlings should be transplanted once they have outgrown their current container. If you notice that the roots are starting to circle around the bottom of the container or that the leaves are touching the edges, it’s time to move them into a bigger pot. Also, at this time, they should have their second set of leaves.
Root Development: Checking the root development of your seedlings is another important factor in determining when to transplant. Gently remove a seedling from its current container and examine its roots. If you see healthy, white roots filling up the pot, it’s a good sign that they are ready for more space. However, if the roots are still sparse and underdeveloped, it’s best to wait a little longer before transplanting.
Harden off seedlings before transplanting
This helps acclimate them to their new environment and reduces transplant shock.
Before transplanting your indoor-started seedlings outdoors, hardening them off gradually is essential. If this is not done, they will not be prepared for the outdoor weather and will not survive. This process involves exposing them to outdoor conditions like sunlight, wind, and temperature fluctuations over several days up to a couple of weeks before transplanting them into your garden.
Congratulations! After you have hardened off your seedlings and your last recorded frost date has passed, it is time to plant your little babies!! This is such an exciting time to take your plants that are now starting to take over your space and plant them in the garden. Read my blog post on Ten Gardening Secrets to Success, where I will go over the things you will need to think about once your seedlings go into the ground or raised garden beds.
In the blog post, Ten Garden Secrets to Success I will go over the following:
- Garden Direction
- Weed Control
- Soil Conditions
- Watering and Drip Systems
- Wildlife Fencing
- Raised Beds or Mounds
- Last Spring & First Fall Frost Dates
- Planting Zone
- Companion Planting
- Garden Rotation
Starting seeds indoors can be a fun and rewarding way to kickstart your garden while saving money on store-bought plants. By following these tips and tricks for success, you’ll be well on your way to growing healthy and thriving plants from seed in no time. So grab your gardening gloves and get ready to enjoy the fruits of your labor!
Happy planting!
For more garden growing guides from seeds to harvest, browse the Garden Problems & Fixes hub.
More posts you might enjoy
- 30 Flowers and Herbs That Repel Pests Naturally in Your Garden
- How to Get Rid of Plant Gnats on Plants and Seedlings
- Now is the Time to Plant a Victory Garden
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Hi, I’m Yvonne — the voice behind Our Country Life. I share from-scratch recipes, garden know-how, and simple living inspiration rooted in real farmhouse life. Thanks for being here ❤️
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