This week I wanted to discuss some of the basic elements of seed starting indoors and how over the years I have refined my system to have consistently great results. Things around here have come a long way from the cookie sheets and shop lights in the spare bedroom when I first started gardening, and I thought sharing that information might help you get started if you're thinking about it.
I am going to attempt to speak in generalities throughout this post and discuss the elements that you need to consider, and then I will share with you where I am currently in my ever evolving seed starting system. We start seeds in all kinds of places, both indoors and out, but this post is going to focus on the indoor aspect since around here it's still far too early to be using our greenhouse spaces just yet. Everything outside is still very frozen.
I would also add before we dive in that while there may be some start up costs to consider, the system that you will be developing has wide ranging implications. I have used the systems I will be describing here to grow salad greens indoors throughout the winter. I have yet to try it, but microgreens could also be grown in this type of a system so you can surely expand on your usage of the system should you desire too. Let’s dive into the elements of the system.
The first thing you need to consider is space. Where will all this activity be happening? Many folks gravitate towards a south facing spare room or some other space with good light, but just as many if not more choose their basement or even a heated shed. Keep in mind that there will be water present for the maintenance of plants, maybe even some light fertilizer so carpet might not be the best choice if you have options without it. And don’t think that it has to be a room, last year our indoor space was in the dining area of our kitchen behind the table. We were obviously limited on how many starts we could maintain, but it worked out great.
Don’t underestimate the value of vertical space when seed starting as well. We’ve started using wire shelving units from big box stores. The really large ones can easily hold four starting trays per shelf, which means in a four foot by two foot amount of space I am able to start 12-16 trays full of plants. Which is my current go to for this section. I highly recommend these large wire shelving units. You can find them at places like Costco, Home Depot, or Lowes. They offer a lot of benefits that we will discuss later.
TRAYS AND MEDIA
You are going to need something to hold your seedlings and it needs to be watertight. There are lots of DIY options here, like the baking tray I mentioned starting with years ago, but save yourself the hassle and find some 1020 seed starting trays. You can find these at the big box stores, or hit up a nursery supply store and buy them in bulk. If you take care of them, they last for years and are so convenient to store when not in use. They also make great trays for doing microgreens. A word to the wise, there are shorter and taller versions of these trays. Depending upon how you're doing things, the shorter ones might meet your needs better.
What to put in those trays is a huge debate among growers, and they all have their pros and cons. I will
dive deeper into this in a later post, but for now know that I have used standard cells, soil blocks, and the peat pucks from Jiffy and love them all for different reasons. I did a video on seed starting mixes and how to make your own, so don’t waste money buying the ready made stuff, especially if you are going to be starting lots of seeds. It’s so easy to make. Just be sure to keep it neutral and feed the seedlings with liquid based fertilizers.
To be clear, that means don’t make the mistake I did and mix in worm castings or compost with your seed starting mixes unless you know for sure that it is free of germinating seeds. Last year my tomato starts had some surprising results since the composted tomatoes from the previous season didn’t get killed out and random tomatoes began sprouting up. This year I will be sticking with neutral starting media and will pot up seedlings into compost when necessary so I can be sure I am getting what I want when I drop those plants in the ground. Peat moss, coco coir, and some vermiculite is all you need to get seeds off to a good start. Thank me later.
This one probably goes without saying, but it is really nice to have a long spouted watering can. I have one that I am sure was intended for house plants and it works perfectly. I don’t generally water seedlings from the top when starting them indoors once they have sprouted, rather I keep some water in the 1020 tray and allow it to wick up to the plants from below. This is also a great way to get them a bit of a feed if you need to keep them growing inside by adding some compost tea or other dilute liquid fertilizer.
I am by no means an expert here, but I do know that you are going to need lights. Now I have started plenty of seedlings using standard fluorescent shop lights. I have used the fancy plant grow bulbs and regular bright white bulbs all with success. What is nice about these is they throw off some heat, which is a benefit for sure. LED lights have sorta changed the game though, and now I use specific LED grow lights for my indoor seed starting. They are widely available online and I order most of mine from Amazon. They come in a wide range of sizes and options.
One thing that I have started doing which was a real game changer is using some foil covered bubble wrap to help reflect light and keep it available to the seedlings. You can buy rolls of this material at hardware stores or online. It is used as a reflective insulation, but for our purposes it's absolutely perfect to both trap some heat and reflect light in our seed starting system.
The last element to consider is heat. For years I underestimated how important this was, and then my wife bought a seed starting heat mat and it changed everything. Having some gentle heat under your plants is a massive benefit, especially for things like tomatoes and peppers who love the heat. So I now fully endorse the use of this tool as I think it will greatly increase your success. Again you will find lots of options online, I even ordered a double tray unit last year and I love them.
Final thought to consider is power. These systems are of course heavily reliant on electricity to run the lights and heat mats, so be sure to consider access to power, perhaps a good quality power strip, and some sort of a timer to control the on/off cycle of your lights. This way you won’t have to worry about turning on and off your lights if you happen to be away for the weekend or out late. I shoot for about 12-16 hours of light when setting the timer.
So, from start to finish, here is our current set up.
Start with a wire shelving unit, assembled with even spacing of the shelves. Somewhere around 16-20 inches of space between shelves. You can have some shelves deeper for taller seedlings if you want.
Under each shelf, hang your light system of choice. I am not going to get into the specifics of this as it will depend heavily on what lights you choose. You can use a light duty chain and S hooks to control the height of your light and hang them from the wire shelf above, which is why I love this system so much. So easy to mount lights.
On top of each shelf place your heat mats if using them. I have used this system without them and found great success, but that was indoors where the room was fully heated to around 70 degrees. If you're doing it in a basement or heated shed like we are now, the heat mat might be more important.
Place 2-4 1020 trays per shelf depending upon the size of your system and fill them with the seed starting media of your choice. I will have a more detailed post on options soon, but no matter what you choose it should work just fine. Plant your seeds and cover them with the clear humidity domes until the seedlings start growing.
Wrap the entire shelving unit in foil coated bubble wrap to reflect the light throughout the growing space. I use simple binder clips to clip the bubble wrap around the top shelf to hold it in place. It’s fine if it isn’t closed all the way, we just want it to reflect light so your plants are getting hit from all directions.
Plug everything into a power strip that is on a dedicated timer to control the amount of light and you're off to the races. At this point, your only job is to keep the seedlings watered, and maybe give them a feed or two before you are ready to plant them out or pot them up.
I have found this system to be highly effective and a good use of the limited space we have available for setting something like this up. In a very small footprint, I can start hundreds of seedlings and get them off to a good start so we hit the ground running once the spring weather breaks. Let me know in the comments how you start seeds indoors and any recommendations you have for specific lights, fertilizers for seedlings, or your favorite seed starting media. Questions are always welcome and we’ll do our best to get you an answer. That’s all for this post so get outside and get growing, because life is better when it’s lived Outdoorz!