Tips for planting seeds indoors

Pots with planted seeds sitting on my windowsill facing southwest. Photo by Diane M. Lilly, 2022.

Over the years, I have looked forward to planting seeds indoors. I love watching the fragile green seedlings push their way up through the moist soil and begin to sprout. We live in a rental home, so digging up the yard is not an option and limits my ability to grow vegetables and herbs. We have a small raised garden for growing mint, sage, and chives, and there are also usually a few containers on the back patio where herbs like cilantro, parsley, dill, and chamomile grow over the spring and summer. So this year, I wanted to plant more herbs in containers, with the idea that they can be placed outdoors on the patio or indoors on a windowsill, keeping my houseplants company.

My raised garden from 2020 with sage, chives, and mint. Photo by Diane M. Lilly, 2020.

What type of containers you will need

In previous years, the seeds were planted in small grow pots or even styrofoam cups, then transplanted into larger containers once they were strong enough. This year, however, I’m going to try something a little different…I will plant them directly in the pots so I don’t have to worry about stressing them during the transplant process. It may become necessary to eventually transplant them anyway, but for now, that’s the plan! 

Honestly, I don’t do a lot of fancy stuff when I plant seeds. I’ll use any small pot or container on hand and cover it with plastic when the seeds are planted to keep in the moisture and warmth the seeds need to grow.

When to plant seeds

Generally speaking, early spring is a ideal time to start, anytime between March and May. Certain seeds—like tomatoes—need to be planted earlier, so that you get your fruit during the summer growing season. It’s a good idea to read all the information on the packet. This will provide information about when to plant, how deep to plant, how to space your plants, lighting and watering needs, etc. It’s also a good idea to do a little research first. Figure out what types of plants will work best for your own space, lighting, and experience, and start with just a few pots when you are first getting started. Each year you’ll learn more about planting and grow better plants!

What I’m planting this year

This year I have a wide range of seeds I’d like to try. For my vegetables I decided to plant cherry tomato and cucumber seeds—even though I am really planting them a bit late in the season, but better late than never! As for my herbs, this year’s seedlings will consist of cilantro, dill, basil, lavender, thyme, sage, and rosemary, all of which I’ve grown previously. The packet instructions for thyme, rosemary, and sage say to plant the seeds in May, but these will possibly end up as indoor herbs anyway, so I’m going ahead with planting them now along with everything else. I have to say, I’ve never had any luck with lavender and rosemary, but my stubborn streak won out and I’m trying again this year. If these herb plants don’t grow for me I can always buy a plant at my local home and garden store…but I am determined to have lavender and rosemary in my life! There is one last thing I want to plant—catgrass—but I need a special flat pot for that plant. It’s something special for my cats and they will want to eat it and roll in it…at least that’s the plan. You never know with cats!

My seed packets for this year. Photo by Diane M. Lilly, 2022.

What type of soil to use

So this might be the most intimidating part of the process! Different gardeners have their own secrets for creating good soil for specific types of plants. There are many different ways to mix soils to get perfect balance of nutrients and drainage, and that becomes really important when the plant matures. But that’s a topic for another day! Today I simply want to plant my seeds in small pots with basic soil with little fuss. Basically you just need a good quality soil that drains well and has a good ph level (6.0-7.0). Important to note—read the descriptions on soil bags carefully. Some potting mix is specifically made for in-ground gardening, whereas some soils are used exclusively for growing in containers. For my needs, I am using MiracleGro Seed Starting Potting Mix (good for containers) to get my seedlings started, and I’ll mix up my own soil later when (and if) I transplant them.

Slightly larger pots for tomato and cucumber seeds. Photo by Diane M. Lilly, 2022.

Smaller pots for herb seeds. Photo by Diane M. Lilly, 2022.

Empty pots ready for potting soil. Photo by Diane M. Lilly, 2022.

How to plant the seeds

Planting seeds really isn’t hard. Basically, you just put some soil in whatever starting pot you’d like, tap the bottom a few times to get rid of air pockets, then fill more soil if necessary. Then follow the planting instructions on the label for your particular seed. Pay attention to planting depth and spacing requirements. All of the seeds I planted this year required a depth of 1/4 inch, and this can be done in a couple ways. You can either poke small holes in the soil and drop the seeds in, covering up the holes afterwards, or you can place the seeds on top of the soil and cover with more soil. I’ve done it both ways. It really doesn’t matter, as long as the seedings are able to find their way to the surface when they begin to sprout. Once you have your seeds planted, it’s time for watering.

Pots filled with soil. Photo by Diane M. Lilly, 2022.

Pots for herbs, seeds planted and pots labeled. Photo by Diane M. Lilly, 2022.

Pots for tomaties and cucumbers filled with soil. Photo by Diane M. Lilly, 2022.

Tomato and cucumber seeds planted in pots and labeled. Photo by Diane M. Lilly, 2022.

All of my newly planted seed pots ready for watering. Photo by Diane M. Lilly, 2022.

Watering the seedlings

Water enough that the surface of the soil down to the depth of the seeds is wet, but do not drown the seeds. If you water too much you’ll just end up with soggy soil that can rot your seeds before they get a chance to grow. My method has been to water, the cover the pots with plastic wrap to keep the plant moist and somewhat warm, then every couple of days I’ll check each plant to see if it needs more water. I’m just looking to keep the soil moist but not wet. This usually means I water carefully with a teaspoon or a spray bottle at first, a little at a time so I don’t accidentally overwater. Once the seedlings start to sprout enough that they almost touch the plastic, I remove it so they can grow free. The bigger the plants get, the more water they will eventually need.

Seed pots and watering can. Photo by Diane M. Lilly, 2022.

Pots watered and getting a plastic wrap covering. Photo by Diane M. Lilly, 2022.

All my newly planted seed pots, watered and securely covered in plastic wrap. Photo by Diane M. Lilly, 2022.

​Finding the right light

For most seedlings they really just need a lot of light to help them germinate and sprout. Plant specific light levels become more important once the plant matures a little, so when I first start my seeds I place the pots on a southern facing windowsill. (In my house, my windows face southeast and southwest.) This way the seedlings can make the most of the daylight and sun while they are trying to germinate. I don’t have fancy grow lights either. The plan is to buy a couple eventually (because they are a great investment for growing seeds indoors), but for now I just let the natural light on my windowsill do the job.

When to transplant

Transplanting can be a stressful time—for you and your plant! The key is to go slowly be careful, and read up ahead of time any instructions for separating and replanting your new plants. Doing research will result in better knowledge and answer questions like: What type of soil does this plant need? What are its lighting needs? Will it be too hot? Or too cold? Learning the basic needs of your new plant will give it the best shot possible to survive. And they don’t all survive! It’s just the way it is. Just keep trying and celebrate the ones that make it! (I will do a separate blog later on in the transplanting process.)

Another shot of my seed pots sitting on my living room windowsill. Photo by Diane M. Lilly, 2022.

​I’ll more than likely create another separate blog later for cucumbers and tomatoes, as they get big and will need bigger pots. A few of the herbs may get transplanted as well, depending on what they need later in the spring (and how much space I have). There is a lot to know about soil types and ph levels (and a lot I am still learning), but I think I will tackle that topic in a later blog as well. 

There are some common mistakes to avoid when starting seeds—such as over watering, seeds planted too deep, not enough light, wrong temperature, etc.—but it’s really not hard to plop a few seeds in some dirt and see what happens! Just remember this…There are people out there who have been doing this for years, and have every step of the process down to a science…but seeds and plants grow perfectly well on their own out in nature much of the time, without our interference! Just have fun planting and see what happens!

​Related blogs you may want to read:
How to repot a pothos plant
Small houseplants that love bathroom humidity
A spring decor makeover for my small rental bathroom 
How to propagate bromeliad pups
Eight health benefits of decorating with plants
Six herbs I planted indoors
Let’s talk about houseplants
Biophilia in interior design

This article may contain a few items or commercial mentions, but I only used them for demonstration purposes only. I am not endorsing any particular product or receiving any monetary gain for this blog.