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  • Writer's pictureSheri

How to Start Seeds Indoors

If you aren't growing at least a small portion of your own food, now is a great time to start!

On our farm, we have a basement room with grow lights where we start our seeds indoors. Back when we were selling large quantities of produce to customers, we started indoors primarily in order to have tomatoes and other popular items very early in the season. But now that we are growing only for our own family, we still start many seeds indoors. Even if you have only a small space to work with, you can likely still start at least some of your own seeds!

There are two primary reasons you may wish to start seeds indoors:

1. To extend your growing season

2. For better quality control.

Extend your growing season

In many areas, extending the growing season is necessary to allow certain crops to get enough time to fully produce. This is usually the case in colder climates and for certain crops that have a longer production time such as tomatoes, peppers, cucumbers, and melons.

This is exactly why we start our seeds indoors and we also use a greenhouse to help us. But you can use a small hoop-house or small portable greenhouse to help you extend your season.

Growing seeds indoors can also be used in mid-summer when the soil and weather are too hot to germinate certain seeds. We do this with several varieties of plants that we want to last into fall. We’ll start them indoors midsummer, then transplant them once the weather isn’t so hot.

Controlling the Quality

By starting your seeds indoors you can control the environment which means you can control the outcome with much more accuracy.

Once you learn how to grow seeds indoors you can control the temperature, the light exposure, and even the moisture level.

With all this control, you’ll yield a much higher germination rate, which in turn saves you money because you don’t have to buy as many seeds to get the yield you want. You’ll also have stronger plants that will resist bugs and disease much better.

When Should You Start?

This answer will depend on a number of things! If you want to get your started plants into the ground as early as possible, you will need to know your last frost date for your area BEFORE you start your seeds.

In our area, the last typical frost date isn’t until May and we have learned the hard way that placing tomatoes into the ground in late April could still present an unexpected freeze which kills off our hard work! So be sure you have researched this information for your area.

You will also want to know when your FIRST frost date is for the fall. Then you can backtrack to ensure the things you are planting will have time to be harvested before the first frost. Some crops do well in colder weather and can be harvested through the fall, while others will not be ready. For this reason, there are certain crops we don’t raise at all because we know we won’t get enough time to harvest them. (Unless we are using the greenhouses.)

Know What You’re Planting

Before knowing HOW to grow plants indoors, you should have an idea of WHAT you want to grow. Find a reputable seed company and grab their catalog. Be sure to use a trusted source. We love Johnny’s Seeds because they have a large selection, do a good job of describing how to grow all of their seeds and typically have good instruction videos. They are also who we used to determine our best seed-starting soil. You can see that information in this video here. There are several other seed companies we like. We tend to go with the companies that have organic selections.

Each plant will have a different germination time (how long it takes for the seeds to sprout) and time to harvest. Working backward you’re going to want to come up with a plan on when to start each plant indoors.

Get a Garden Planner

Our favorite tool for planning when to start seeds indoors is to use a garden planner. We use an online planner but there are many you can choose from with a quick google search. You may not need anything as robust as the one we use if you are only doing a small garden. We use this one. But we have also heard great things about Clyde’s Garden Planner so you may want to check that out.

All of these planners help you get the general information you need so you can plan the best time to start and harvest your plants.


Knowing when to transplant your starts outdoors also depends on the size of your seed starting pots or trays.

A general rule of thumb is that you’ll start your seeds 4-8 weeks before transplanting them outside. But if you need to extend this time a bit longer (say for tomatoes which have a longer growing season), you might need larger pots to allow the plants to grow bigger.

We actually start our seeds in soil blocks instead of pots and we highly recommend this method. You can learn more about it here on a video we made.

We many times do need to transfer our plants from the soil blocks tray into a pot before they actually go into the ground and in that case, we choose a size pot based on how long we think it will need to be in the pot before making its final landing into the garden.

Which Seeds Can You Start Indoors

Technically speaking, you can start ANY seeds indoors. But this doesn’t necessarily mean you need to.

Some seeds are easier than others, so it just depends on whether you need that extra control that starting seeds indoors gives you.

Again, if you know your climate, the length of your growing season, your average temperatures and if you have healthy soil, then many plants can be directly sown outdoors with no problems.

For us in southern Missouri, we will always start tomatoes, peppers, cucumbers, melons, and cabbage indoors because our growing season just isn’t long enough and we want to have veggies as soon as possible. We also start lettuce indoors because we try to have our own lettuce available nearly year-round by harvesting right from our grow room or from a greenhouse.

However, colder-weather crops such as lettuces and cabbages can be directly sown in early Spring.

What Do You Need To Start Seeds Indoors

You don’t need an elaborate system to start seeds indoors, however, there are a few items that will be helpful:

· Seeds

· Trays and pots

· Markers

· Potting soil (we make our own, see recipe here.)

· Water

· Grow lights or a sunny window


As we mentioned before, make sure your seeds are high quality and that you’ve checked the seed packets for how long it takes the seeds to germinate, when you should plant outdoors, and the average time to harvest. This will give you an idea of when you should sow seeds.


There are many options when it comes to seed starting trays and pots. Some people prefer to grow in peat pots, others in large trays with multiple compartments. We prefer to use a soil starting mix created into “soil blocks”. We prefer this method because it allows us to use space wisely, and it allows the roots of the started plants to get oxygen and therefore reduces stress when transplanting.

We use smaller trays that are more sturdy, reusable and because we plant our garden in sections with a variety of items. Having our starts in smaller trays allows us to do more variety and extend our growing in such a way that we always have new plants going out. For example, we may start a few tomato plants early and then have more tomato plants that will be ready every few weeks. That way when our first plants slow down, there are always more ready to produce keeping us with good tomatoes through the whole season.

slightly larger individual pots.


Having markers is very important for remembering which type and which variety of seeds you’ve planted. Trust me when I say there’s nothing worse than getting all your seeds planted and then not remembering what you put where.

Label everything! No matter how much I think I will remember, I typically always forget and you may do the same thing.

We use plastic markers because they’re reusable and will last for many years.


When starting seeds indoors you’ll want to have a seed-starting soil that’s moist but not too wet. It should just hold together when squeezed with your hands (see photo above), but not stick to your hands or turn your hands black.

We actually don’t recommend buying potting mix from garden centers because they’re typically sterilized before bagging and devoid of life. See hour soil mix post or video to learn more about seed starting soil.

If you’re going to spend your money, spend it on a high quality compost over a seed starting mix.


You’ll want to have water on hand because your soil will need to stay nice and damp to allow for germination.

When you’re watering your starts for the first time, you’ll need to water them a lot more than at any other time.

For our seed trays, this means filling it up 1/2-2/3 full then giving the plants 12-24 hours to “drink up” all that water. If there is still water in the tray after 24 hours, dump that water out and begin watering normally each day.

If after 12-24 hours the tray is dry, add water to fill the tray about 1/4-1/2 full again and wait another 12 hours. Then remove any excess water.

Grow Lights or a Sunny Window

Once your seeds are planted, they’ll need light. Using grow lights or a nice sunny window will work great.

Heat mats are another good possibility. But we have had success with just typical lights like these, hung on shelves like these, in our basement “grow room.”

We actually prefer growing starts in the basement because it’s easier to control the temperature and light using heat mats and grow lights.

If you’d rather not invest in mats or lights, you can adjust by finding a sunny windowsill, or a warm, well-lit area of the house. But we have found this is nowhere near as effective and sometimes using this method creates “leggy” plants that don’t do well. It is best to invest in a basic grow light and not all that expensive to do so.

We found using fluorescent lights works well as a light source, especially if you’re only growing for about 4-6 weeks before transplanting. If you go much longer than that your plants could end up lanky and weak without access to a stronger light source.

We keep the lights about an inch above the plants and, as they grow, move the light up.

Additional Seed Starting Tips

1. We use this tool to create a small indent in our soil blocks where the seed will sit. Typically we don’t want to cover the seed with much so we use a light dusting only over the seed.

2. We spray our seeds to keep them damp or we water from the “bottom up” to allow our soil blocks to absorb the water. For some we have also tried putting "plastic wrap" on top of the whole tray, which creates a greenhouse of sorts for the seeds. This enables us to be away for days without watering the new seeds!

3. We don’t like to poke “holes” in our soil where the seeds will go. Oftentimes we find our seeds get too deep this way. The only exception to this rule is for larger seeds like corn or beans.

4. Water from the bottom up! This helps you know your plants are neither too dry or too damp.

5. If you have extra seeds after planting, store them well and they should be good the following year. If planting older seeds, we generally plant a couple extra.

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