Germinating seeds indoors is a great way to get a jump on your gardening for the next growing season. Today’s blog is just a quick checklist for what you need, and why, to start germinating seeds indoors. The tips are highlighted and more explanation follows each one. Enjoy! For more detailed seed starting information, be sure to check out the link at the end of this blog and also our additional 3 Part Seed Starting Series.
Checklist for Starting Seeds Successfully by Germinating Indoors
Choose the right seeds for starting indoors at the right time of year.
The best seeds to start in January are your warm weather loving veggies and early spring flowers. Seeds like tomatoes, peppers, eggplant, etc… can be started indoors ahead of time (we actually encourage you to start tomatoes indoors) as well as seeds of alyssum, lobelia, etc… (flowers that like the warmer temps of spring but not the hot temps of summer).
Extra note: Seeds of veggies and flowers that have a long taproot are not recommended for starting indoors as they as they can be damaged when transplanting; leave these to be direct-seeded into garden plots. (Ex: carrots, radish, most milkweeds)
Scarifying or Soaking Seeds
Some seeds have an extremely hard outer shell and in order to have a better chance germinating them, you need to break through them somehow (ex: bluebonnets, morning glories, etc…). Two easy ways to break through the outer shell are by scarifying or soaking the seeds.
Scarifying is using a nail file or piece of sandpaper to gently rub against the seeds to remove a bit of the outer shell. Some gardeners choose to use a knife to nick seeds. Somehow, the tiny size of many seeds and the sharp blade of a knife has me thinking of a bloodbath waiting to happen, so I choose the sandpaper.
You can also soak seeds overnight in a bowl of warm water to soften the outer shell. Don’t forget about them though, or you’ll be left with waterlogged seeds. Don’t soak seeds longer than overnight.
Soil and Moisture for Starting Seeds
Choose a bag of seed starting medium to germinate seeds (lightweight soil mix specifically for seed starting). We carry these mixes in bags for around $6 – $7 dollars at the nursery. This mix is full of perlite, vermiculite, and/or peat, which are much lighter weight materials than a regular bag of potting soil or garden soil.
The growing roots of your seeds need to be able to penetrate through the soil medium, which this seed starting mixture allows for. Lighter soil mediums also provide sufficient aeration and easier drainage, which help to prevent root rot, a sure cause of death to your seeds planted in heavy soil.
Make sure to dampen the soil medium prior to planting your seeds. Place the soil medium in a bowl with some water and then allow it to drain for a while in a strainer before putting it in your pots. The soil should be damp enough to get germination kicked off, but not so wet it will cause the seeds to rot. Clear as mud?
Your pots of seeds and soil will be covered with plastic soon and that will help keep moisture in until you need take the plastic off (more about that later).
Containers for seeds
You can grow seeds in pretty much any type of container, provided the container has drainage holes and that the container starts out small enough to not be overwhelmed by an excess of soil mix and moisture.
2” peat pots are great for starting seeds. Recycled 4” nursery pots work well too, provided you sanitize them with a 9:1 ratio of water-to- bleach, or you can buy a tray designed for starting seeds that has little 2” cells in rows.
(A side story about planting peat pots in the garden once your transplants are ready: While peat pots are purported to be able to go straight into the ground without removing the plant from them, we have found that it is better to gently remove at least the bottom of the peat pot to allow for the roots to definitely make contact with the soil in your garden. We usually try to pull off more of the peat pot surrounding the roots…GENTLY! There have been times when folks brought in an obviously struggling plant and once we investigated and the plant was unearthed, we saw that the roots were wrapped around and bound in the peat pot and had never been able to stretch out and touch the rich potting soil prepared for them to live in. Very sad. We usually advise gently peeling off the peat pots.)
Plant more seeds than needed
Poke about three tiny holes into the growing medium with a pencil and place a seed in each hole. There are many variables when growing seeds that decide if your seed will germinate successfully; by planting more seeds than you need, you will increase the probability that one of your seeds will grow successfully. (Generally, finer seeds are planted closer to the top, and larger seeds can be pushed a bit further down.)
Cover your seeds for warmth
Cover your containers with some type of plastic film to keep seeds moist and warm. Some seed trays include a plastic top, but you can slide a seed tray into a clear plastic bag and tie it closed too.
While covering your seeds with plastic wrap will keep in the warmth needed for seed germination, you can also give your seeds a little more warmth with the use of a heating mat, or incandescent Christmas lights placed around or under the bottoms of your pots. The lights give off just enough heat through the night to speed up the germination process.
Those are the basic needs for starting the germination process of seeds. That gets the seeds going, and then you need to move on to the next step of the seed growing process, which is indoor seedling maintenance. Intrigued? I hope so. Read more about Indoor Seedling Maintenance here. 2021 can be the year of new beginnings in more ways than one! Grow some seeds and learn a new life skill!
The Happy Gardener, Lisa Mulroy