While the weather continues to wreak havoc on our outdoor garden, starting seeds indoors can bring a bright spot to our lives. There’s something wonderful about being up close and personal with the growing experience.

I began my indoor seed starting journey about three years ago. That was after many years of failed attempts. Once I got serious about growing seeds indoors, I set out to learn as much as I could about the process. And now I’m hooked and will never go back to only planting seeds outdoors.

In this post we’re going to dive into the basics of starting seeds indoors. Who knows, maybe you’ll develop the indoor seed starting bug as well.

Why Start Your Seeds Indoors…

There are many reasons you might start some of your seeds indoors this year. Here are four main reasons to consider starting some of your seeds early.

#1— Get a Jumpstart on Spring Planting

One of the best reasons to start seeds indoors is that you’ll get a head start on spring planting. If you start your seeds early, then you’ll have larger plants to transplant in the spring. By transplanting a 6-week old plant outdoors, you’ll get flowers, herbs and produce sooner than if you start your seeds outdoors after the last frost.

Some seeds have a long growing season and need a head start, especially if you live in a colder climate. Plants such as tomatoes and peppers can benefit from a head start.

#2— Save Money

Another valuable reason to plant from seed is the cost. You can grow far more plants from the purchase of a seed packet than you can if you purchase transplants. This can help you to not only save money on your plants, but if you plant a few extras, you’ll have backup plants if something dies. You’ll also have a few extra plants to share.

#3— A Larger Selection of Plants

Growing your flowers, herbs, and vegetables from seeds will give you a much larger selection of plants to choose from. When you purchase plants from a nursery, you’re stuck with what they have available. But if you buy seeds, there are so many more options.

You can purchase seeds from a local nursery, garden center, or even your grocery store. But the selection is even greater if you turn to a seed company such as Botanical Interests, Johnny’s Seeds, or Territorial Seeds.

#4— You Get to Start the Growing Season Earlier

The fourth beneficial reason for growing indoors from seeds is that you get to start gardening earlier. If you can’t wait to dig into the garden, then you can get that spring planting experience early by starting from seed. I can’t express the excitement of watching those newly planted seeds start popping up right before your eyes.

Even when it’s cold and blustery outside, you’ll have a little garden growing inside.

What Seeds to Start Indoors…

There are many plants that do well when grown indoors. Here is a list of some of my favorites to start indoors.

Flowers…

• Dahlias
• Foxglove
• Snapdragons
• Sweet William
• Zinnias
• Impatians

Herbs…

• Basil
• Chamomile
• Sage
• Oregano
• Parsley

Vegetables…

• Tomatoes
• Peppers
• Cabbage
• Cucumber
• Celery

What to Avoid Planting Indoors…

Not all seeds do well when started indoors. There are some plants that prefer not to have their roots disturbed by transplanting. These plants grow much better when they are direct sown into the garden. Don’t waste of your time and resources planting these indoors. Here are plants that will grow better if planted directly into the ground once it’s warm enough:

• Sunflowers
• Cosmos
• Root crops such as Carrots and Radishes
• Garlic
• Squash, Summer and Winter
• Green Beans
• Peas, Regular and Snap
• Pumpkins
• Cilantro
• Dill

Note… If you really want to start these early, then start them in biodegradable pots. Then you can just plant the whole thing into the garden without disturbing their roots. So, if you want to get a head start on monster-sized pumpkins, consider starting them in peat pots.

When to Start Your Seeds…

The timing for indoor seed starting is a little tricky. If you start them too soon, you can end up with plants that become root bound. If you plant them late, then you’ll need to wait to transplant them. So how do you decide when to start your seeds? Follow these steps to decide on your best time…

Know Your Dates

Start by figuring out your last frost date. This is key to planting your seeds correctly. You can find your first and last frost dates at The National Gardening Association.

Choose your last frost date with no risk of a frost or select a slight risk, such as a 10%, 20%, or 30% chance of still having a frost. By choosing a slight risk, you can get your plants in the ground sooner. I’m okay with a small risk because I can cover the plants with frost cloth if a light frost is in the forecast.

Choose Your Seeds

Decide what you want to grow indoors. Look at your seed packets to determine if they are a cool season or a warm season crop. Cool season plants or hardy annuals, love to go into the ground earlier in the spring. They’ll need to be started earlier than the warm season crops that love it hot.

The seed packets will tell you how soon before the last frost to plant seeds indoors. It could be two weeks, four weeks, six weeks, or even longer before your last frost, when you need to start your seeds. I organize seeds into categories based on how soon to start them. Then, at the recommended time, seed them into your trays.

If you’re just getting started with indoor seed starting, choose a few warm season crops that are easy to plan for, such as zinnias or basil.

Another option for determining when to start your seeds indoors is to use an online calculator. Here is a calculator from Johnny’s Seeds that gives a good estimate of the date ranges for indoor seed starting.

Mark Your Calendar

In order to not miss a planting date, put the dates on your garden calendar. I also like to note what to plant at each time frame. So, 6-8 weeks before your last frost, make a note to plant cabbage, broccoli and foxglove. At 4 weeks before your last frost, you might make a notation to plant your tomatoes, peppers and zinnias.

Supplies You Need For Indoor Seed Starting…

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Your supplies will depend on how committed you are to grow seeds indoors. If you’re just starting out, you might not want to spend a lot of money on supplies. Seed packets, trays and seed starting mix are a must. And if you don’t have plenty of sunlight available, then consider getting a grow light.

I tried for many years to start seeds indoors by growing them in a south-facing window. And every year I was not happy with the results… tall, leggy plants that were so spindly I ended up composting them. But once I began using a grow light, it made all the difference in the world.

Initially, I had just one grow light. I grew plants on my dining room table with the grow light hanging from the light fixture. But slowly, over time, I’ve added to my supplies. I’ve purchased a few more grow lights and a 6 foot tall metal rack for my seedling trays.

There are other helpful supplies to purchase, such as a heat mat. And having a fan to strengthen your seedlings is valuable as well. But when you’re just starting out, use what you have and make sure this is something you want to continue with before you invest in a lot of equipment.

Steps to Start Seeds Indoors…

Follow these steps to get started growing indoors.

Step 1— Fill Your Trays

The first step is to fill your trays with a quality seed starting mix. It’s helpful to use an actual seed starting mix rather than potting soil. The starting mix is lighter, which makes it easier for the seeds to germinate. But if all you have is potting soil, pick out any large chunks of wood. Then break the soil up with your hands to make it lighter.

Before you fill the trays, moisten your seed starting mix. Pour it in a bucket or container and add some water. Mix it together and continue to add water until the mix is moist but not soaking wet. If you can wring water out of a handful of mix, then it’s too moist. Why does this matter? If you don’t pre-moisten your soil, it will be very difficult for the potting soil to absorb water after you’ve planted your seeds.

Fill the trays but don’t compact the soil. One way to do this is to tap the tray on the table a few times. Then add more potting mix and tamp again until you’ve filled each hole.

Step 2— Follow Directions For Placing Seeds

Pay attention to the planting directions for your seeds. Some seeds need to be placed on top of the starting mix because they need light to germinate. If you bury those seeds, you’ll get little germination. Other seeds need to be buried to a certain level. If your seeds only need to be lightly covered and you plant them an inch down, you won’t get much germination.

How many seeds to plant per cell will depend on the size of the cells in your container. You can purchase trays with a varying number of cells from a single container to hundreds of cells. For the home gardener, choose a seed tray that ranges from 24 up to 72 cells per tray.

Consider planting 2-3 seeds per cell. Not every seed will germinate. So by planting a couple of seeds, you’re more likely to get at least one plant per cell. If you have too many seeds germinate, you can pinch the extras off or wait until they’re larger and separate them.

LABEL, LABEL, LABEL…. Don’t forget to label your seeds before you move to the next step. Otherwise, you might get them mixed up. Even though you think you’ll remember, you won’t. You can use craft sticks, plastic garden labels, or even a translucent milk jug cut into strips. Whatever works for you. As a backup, I also make a seed tray chart to remind myself of what I planted in case something happens to the marker.

Tip: Plant seeds with similar needs together. Don’t plant a quick germinating or fast-growing seed next to a slow grower. Put them in separate seed trays.

Step 3— Water Seeds Lightly

It’s best to water your seeds from below the container rather than from the top. Top watering can move the seeds out of position. However, you might find a light mist from a spray bottle will settle your seeds initially.

Once your seeds sprout and start to grow, water only from the bottom of the container. In general, giving your plants a drink every few days is good for the plants. Just don’t let them sit in a large amount of water or it could cause the roots to rot.

Fill the bottom of the drain tray with water and allow it to be absorbed for about 30 minutes. Once the top of the soil is moistened, empty out the excess water.

Step 4— Cover Seed Tray With A Dome Lid

Seeds need warmth and moisture to germinate. So it’s helpful to cover your newly planted seeds with a dome. If you don’t have one available, you can cover the top with saran wrap. Keep an eye on the tray. When 50% of your seedlings have sprouted, then remove the covering. If you don’t remove the covering, your seedlings could die.

Place your seed tray in a warm area until the seeds have sprouted. Some people will use a heat mat under the tray to help warm the soil. But there are other ways to warm up the soil. For example, you can place your tray on a radiator, heat register or even the top of your refrigerator.

Step 5— Place Under Lights

Once you have at least 50% germination, it’s time to place your seedlings under light. You don’t need expensive grow lights for this process. Inexpensive shop lights will easily work. Place the light about 2 inches above the seedlings. As the plants grow, move the light up to maintain that spacing.

Leave the light on your seed trays for about 16 hours each day. I turn mine on as soon as I wake up in the morning and off just before going to bed. You can purchase a timer for your lights, but that’s not really necessary.

Note: As your seedlings grow, they can benefit from air movement. Place a small oscillating fan on them for an hour or more each day to help strengthen their stems. Run the fan at a low setting and placed so there is gentle movement, not excessive force. You can also achieve this by running your hand along the tops of the plants occasionally.

Step 6— Transplant If Necessary

As your seedlings grow, some might need to be transplanted into larger containers. Most can remain in your planting tray. By 4 to 6 weeks, the seedlings should be large enough to transplant into the garden. There are some plants, however, that might need to be transplanted into a larger container and allowed to continue growing indoors. A good example would be tomatoes.

Step 7— Harden Off the Plants

Before your seedlings can go into the ground, they will need to be hardened off or prepared for the outdoor environment. Outside, your plants will be exposed to cold, wind, and harsh sunlight. They need time to get used to these changes.

Once your plants are large enough to go outside, start by moving them out into a protected area for a few hours. A shady porch is a good place to start. Bring them back inside afterwards. Each day, leave them out longer and start exposing them to direct sunlight. After a few days, they should be able to spend the day outside. However, don’t forget to bring them in at night or you could lose them to cold temperatures.

After a week or so of daily exposure to the outside world, your plants will be ready to move into the garden.

Step 8— Transplant Outdoors

Time to get your babies moved to their permanent garden home. They’re ready to be planted into your garden containers and beds. Double check your last frost date and move them into the garden.

When planting them, add a little compost and slow release fertilizer to the planting hole.

Tips For Growing Indoors…

• If you’re new to growing seeds indoors, then start slow. Begin with one or two seed trays and experiment with this. Start some of your favorite flowers or grow some tomatoes. Don’t grow too many plants your first year.
• It’s okay to supplement with store-bought plants if your seedlings fail. Each step is a learning experience, and it takes time to get it right.
• Don’t compare yourself to other gardeners. It’s easy to feel like a failure when comparing to a flower farmer or “Instagram” gardener. They might not share their messes and failures, but they have them.
• Some seeds will need to be stratified before planting. So be sure to check the label in plenty of time to put them in your frig or freezer for a week or two.
• Plan for at least 15 to 20 minutes each day to care for your seedlings.

Once you get started growing seeds indoors the right way, you’ll wonder why you’ve never done this before. All it takes is a little time and patience. Before you know it, you’ll be a seed starting expert and you’ll wonder why you waited so long to give indoor seed starting a try.