It’s that time of year! Seed starting time! I love the excitement of picking out favorite seeds and planting new varieties. Finally getting my hands in some dirt. Then there’s the waiting in anticipation as the seeds germinate. Checking every day to see what the progress is. And then the sprouts. How many will come up? And as they pop up one by one, I see that the time and anticipation is all worth it. In this beginner's guide to starting seeds indoors, I will take you step by step through the entire process
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Benefits of Starting Seeds Indoors
There are so many benefits to starting your garden plants from seeds. To read more about the benefits, take a look over here.
It’s not difficult to start your plants from seed. With a little bit of space, a little know-how, some experimentation and patience, you will be ready to go in no time. Keep in mind that how I am telling you to start seeds is my method. Every gardener may do things a little differently, and guess what? That’s ok! You get to pick what works best for you and throw out the rest! Experiment to find out what YOU like to do!
Bonus! Here's a FREE Quick Start Reference Guide for Seed Starting! If you want the entire FREE garden journal and planner that also includes this guide, get it HERE!
Alright, let’s take a look at some seed-starting basics.
Supplies Needed for Starting Seeds Indoors
There are many different options for where you start your seeds. You can use something homemade, like newspaper pots or egg cartons. Or you can use something store bought, like a peat pot, a peat pellet or plastic seed starting trays. Put them in something like these plant growing trays to give them a nice home where you can water them easily.
If you’re watching your budget or just want to try to keep it more sustainable, find things like newspapers, plastic lettuce containers or paper towel rolls to start your seeds. These are great options that you can save throughout the year to have when it’s time to start seeds. Find out how to make your own DIY seed starting containers here.
Beginner's Tips on Materials for Starting Seeds Indoors
My newest seed starting technique is soil blocks. Soil blocks are exactly what they sound like. Water, peat and compost are mixed together and formed into blocks. Then seeds are planted directly in the soil blocks, eliminating the need for other seed starting containers. Here's the soil block makers. Read more about what Eliot Coleman has to say about soil blocks here. And... if you haven't read Eliot Coleman's book, The New Organic Grower, you must!
My go-to used to be peat pots or plastic seed starting trays for the ease and convenience. I reuse the plastic trays year after year. I also try to reuse the peat pots if they didn’t get too damaged the previous year. Peat pots are compostable and can even be planted directly in the ground with your seedlings. Learn more about composting here.
If you are reusing plastic pots, you may want to wash them with soap and water beforehand. Some people recommend using bleach to sterilize pots, but I do not like to use bleach because it is harsh and contains dangerous chemicals. Washing or disinfecting the pots helps to lower the risk of transferring any disease.
Here’s another one that you can buy or diy. I like the plastic domes that fit directly on the seed starting tray. If I don’t have enough, I will just use plastic wrap.
I personally prefer to buy seed starting mix each year to start my seeds indoors. It has a good texture and the right mix to make seed starting that much more successful. You can use regular potting soil if you don’t have seed starting mix available. Just keep in mind that the consistency and nutrients in the seed starting mix are specifically designed for starting seeds. It is also sterile, so there is less chance of your seedlings getting any disease.
A sunny, south-facing window may be enough depending on where you live. You may also consider grow lights. Recently, I've been using these grow lights with great success. Without the proper light, your seedlings will get "leggy" as they try to grow toward whatever light there is.
The top of a refrigerator could work. There are other options as well, like heat mats. For germination, you are shooting for temperatures of around 70 to 75 degrees Fahrenheit.
You can buy your seeds from any trusted source. Learn more about the differences in seeds here. I personally LOVE Baker Creek Heirloom Seeds and buy the majority of my seeds from them. Another good place to buy heirloom and non-heirloom seeds is Ferry Morse Seeds.
It is SO important to label your plants as you plant them. Something as simple as a popsicle stick can work. But if you have the money to spend, you can also try some plant markers. If you love DIY, do a search online, and you will find all types of innovative plant label ideas. Don't forget your permanent marker or plant label marker!
It’s important to think about what vegetables you want to plant and how much you think you will need as you are starting your seeds indoors. Are you planning on eating fresh from your garden? Do you want to preserve anything? Choose vegetables that you and your family enjoy. Keep in mind that seedlings will have to be transplanted from their starter pots to larger pots (such as 2 to 3 inch pots or cups). They will take up a lot more space at this stage.
Work Within Your Budget
One of my favorite things about starting seeds indoors is the options! You can start seeds for just the cost of the packet of seeds or you can buy ALL the things. Or, you can fall anywhere in between. Decide which equipment you would prefer to buy to make your life easier and make seed starting that much more accessible for you.
When to Start Seeds Indoors
Look at the seed packet to see when the seed company recommends you start your seeds. A majority of seeds call for starting 6-8 weeks before your average last frost date. To get a better idea of your average last frost date, look at the Farmers Almanac frost dates search. Keep in mind, this is an average and can vary from year to year. Use this is as an estimate.
Some spring crops like broccoli and cabbage will be started earlier to be transplanted outside before the last frost. Warmer season crops will generally be planted a little later (4-6 weeks before the last frost date).
Where to Start Seeds
Seeds can be started in a greenhouse. If you don’t have a permanent greenhouse, you can look into buying something like this. Just be sure that you can keep a plastic greenhouse warm enough to germinate seeds and grow seedlings (think 70 degrees F). If you don’t have a greenhouse, seeds can also be started anywhere in your home. If you have a south-facing window, that will provide the most light for the seedlings. You will still need to try and get grow lights to give them the 12 to 14 hours of light they need once they have germinated.
I’ve heard of people starting seeds in a basement, spare room or even a closet. One thing to think about is keeping pets away. Cats will love to have a dig in the soil, so make sure that you are set up so that pesky paws stay away from your precious seedlings.
How to Start Seeds Indoors
Fill your seed starting trays or whatever you are using almost to the top with seed starting mix or soil. I prefer the seed starting mix because it is sterile. For me, it is easier to buy it pre-made, but some people like to mix their own. I use a scoop like this to fill my trays, but you can use anything you have handy, like a cup, a container or your hands.
Water the mix thoroughly
Special Instructions and Planting Depth
Make sure to follow any special instructions for the seeds you are starting. Read how to read a seed packet here. Some examples might be to soak the seeds before planting them or to nick the outside coating of the seed.
To figure out how deep to plant the seeds, review the seed packet. Here are some general guidelines:
- For very small seeds, like basil or lettuce, sprinkle a few seeds on top of the soil. Then sprinkle some soil mix on top of the seeds. There’s no need to push small seeds into the soil.
- For medium-sized seeds, such as tomatoes, peppers and eggplant, place seeds on top of soil mix and push down gently. Sprinkle some more of the soil mix on top of the seeds. Most people say to put two seeds in each cell. The reasoning for this is that you should get a better germination rate. The idea is to pick the strongest plant and thin out the rest by pulling the weaker seedling or cutting it off at the base of the stem.
- For larger seeds such as squash and cucumbers, push the seeds down into the soil at least half an inch. Cover fully with more soil mix.
Note, if you are looking to save some space and maximize your seedlings, you can plant many more seeds in each cell or container. This doesn’t work for every seed, but things like tomatoes, peppers and eggplant can be started with many seeds in one cell. This dense planting technique can save space and supplies. I learned about this dense planting technique from Craig LeHoullier. His book, Epic Tomatoes, talks about the process.
Mark the Seedlings
Mark each type of seedling you have planted so you don’t lose track. Trust me, you will NOT remember what’s what. I have tried the memory method of tracking seeds. It makes more sense to use that brain power on something else in your life. You will be happy that you labeled everything.
Water the seedlings
There are a few ways to do this.
This means that you will place water in the bottom of a container that you can put all of your planters into. Let the water soak up through the bottom of the planter. Once it has soaked up to the top, pour out the rest of the water. Just make sure that you do not let the seeds sit in water too long.
Spraying the seeds that you have just planted is a good way to avoid moving them around. Just make sure that you spray enough that the entire planter is moist.
You can use a watering can to water your seeds. Just make sure to go slowly so that you do not disturb the seeds and they don’t wash away. Some people don’t like top watering because it can cause disease issues when foliage gets wet. I haven’t personally experienced disease from top watering, but just be aware that it can be a potential problem.
Cover your seeds
You can use a plastic dome or plastic wrap over your seed starting trays. If you use plastic wrap, make sure that you flip it over each day so that there isn’t too much moisture. Another option is to poke holes in the plastic wrap to provide ventilation.
Put your seed starting trays in a warm spot
For germination to occur when starting seeds indoors, soil should be around 70 to 80 degrees. This is a good range for most seeds, but some seeds prefer warmer or cooler temperatures for germination. Double check your seed packet. If you don’t have a warm enough place, use seed heating mats. Once the seeds have germinated, you will no longer need these.
Now patiently wait for the seeds to germinate. Make sure to keep the soil moist.
Once the seeds have germinated
Once seedlings have emerged, you should remove your dome or plastic wrap. Seedlings need good air circulation to help them thrive. You may not get 100% germination of all of the seeds. If about 50-70% have germinated, it’s time to take off the lid. If you want to check your germination rates ahead of time, take a look at this post that explains how to do so step by step.
- Allow the soil to dry out on top between waterings. Overwatering will leave your soil damp and allow for the growth of fungus. You don’t want that. Remember your options for watering: bottom, top or spray gently.
- Once the seeds have germinated, you will not have to worry as much about the temperature. Generally, seedlings like temperatures of 70 to 75 degrees during the day and between 60 and 65 degrees at night. Again, some crops like lettuce will tolerate much cooler temperatures.
- You will need to put the seedlings under bright light once they have germinated. Most seedlings need more light than what a sunny window can provide. Think about investing in some grow lights or even fluorescent lights. If you stick with a sunny window, make sure to turn the seedlings each day. They will always grow toward the light.
- When your seeds germinate, they have leaves on them called cotyledon leaves or seed leaves. These leaves come from the embryo of the seed and help provide nutrition to the plants as they first start their life. You will see that the seedlings will develop a set of “true leaves” soon after germination.
Once your seedlings have their true leaves, you will want to transplant them to larger pots. In general, if you have planted two seeds per cell or pot, and you want to thin, you would do this now. Just clip the less healthy-looking plant with scissors. I don’t tend to follow this method. I keep and transplant ALL the seedlings!
Some plants are better suited for transplanting. And sometimes, you can transplant things that are generally direct sowed. There is a lot of room for experimentation to see what works best for you in your specific situation. Be creative. A package of seeds is not too expensive, so try some different things to find out what works for you.
Starting seeds indoors is a fun and rewarding experience. At the end of winter, I am ready to get my hands dirty. I can’t wait to get in the garden and start sowing some seeds! It's so much fun to choose my varieties and watch as the seedlings grow. It is truly rewarding to take these seeds through their full life cycle.