Monday, March 5, 2018

Seed Starting

It’s that time of year again! The seed catalogs have all been gone through and dog-eared, most seed orders have been placed, and the packages full of hope for a colorful and delicious growing season are starting to arrive. Now what to do with all those seeds?

In this post I will outline my seed-starting routine. I’ve developed it over the last few years and have honed it into a system that yields a high rate of germination success. I’ve made many, many mistakes over the years, so I’ve learned what works and what doesn’t. This is a bit of long post so I've split in into three parts so you can digest it all at your own rate. 

Part One: Pay Dirt

Let’s start with the tools of the trade. 

First of all, you need what I like to call my “seed starting infrastructure” (this infrastructure also includes heat mats and lights, but we’ll get to that later on). You’ll need a tray with cells (I don’t soil block, but you’re welcome to. Skip ahead to the next step if you are a soil blocker.) My favorite is the 128 tray, which means, simply, that it has 128 cells. That’s a lot. Unless you have a big space to fill or plan on giving away a lot of plants, one of the smaller trays from your garden center or online resource is just fine. 

Now you need some potting soil. Not dirt, but potting soil. Most garden soil is too dense for starting seeds. Also, potting soil has been sterilized, so you know there are no bad actors in your purchased mix. Make certain you get the “seed starting” or “germination” mix. It does make a difference. You can use it straight or you can mix in extra perlite, vermiculite, or even sterile compost. I use a ratio of 3:1 and add organic compost to mine, mostly because I like the texture better and feel like it holds moisture a little better.

I have this nice green potting soil holder that I make my mix in. I just use this old pimento cheese container to move the potting medium around. (I love to re-use items that would otherwise go into recycling). Once the potting medium and and compost are mixed, I push it to the back of the green potting box and place the cell tray in the front. Then I take that same plastic container and dump the mixture across the top of the cells. After I’ve covered the whole surface, I’ll give the tray a few gentle pats around the surface to make certain there are no air pockets in any of the cells. Then I carefully push away the excess. 

Voila! Your first tray filled with potting medium!

Then I pop this 128 tray into a holding tray, which is a 1020 tray. (I really have no idea why this is called a 1020 tray, but it is. If you’re using another size cell tray, you will use another holding tray other than the 1020. Be sure to use one that correctly fits your cell tray.) Then I move over to my seed starting table to begin placing seeds into the cells. 

Part Two: Tucking in the Babies

You’ll need your seed packets, a pair of scissors to open them with, and a small bowl to put them into. I know you’re excited, but take a breath! Don’t just tear open those seed packets. Seriously. I’ve done this — been so excited to get planting, I ripped the package open just to have the baby seeds fly across the room. Don’t do that! Cut open the package and dump them into the little bowl. Don’t use your hand as your seed receptacle unless they are really big seeds. They’ll literally slip between your fingers. And they are much harder to pick up out of your palm than they are out of a small bowl. 

Now, before we go any further, I want to talk about two things: documentation and seeding tools. 

Would you like to know how I’ve learned what works for me and what doesn’t? I document. Both failures and successes. There are some unusual varieties I’ve grown that I’ve found conflicting seed starting information for. So you know what I do? I had a wonderful helper who called it my “science fair experiments”. I try the various advice that I have gathered and document which techniques work the best. Some sources might say to bury a seed. Others might say it needs light to germinate (many seeds do), so to “surface sow” the seed. My advice: try both! Keep track of which way worked better and increased germination.

Here are some photos from my big seed-starting manual, importantly titled, “How to Grow Stuff.” You can see what facts I document. 

I’ll go back to these pages and document the date of germination and other important facts, even continuing once seedlings are planted out and start to mature. All this information is referred to as a plant’s “culture”. So if you hear the phrase “cultural information” about a specific variety, know that it means the best practices and circumstances with which to grow that plant and achieve the highest success. Does it like shade? Full sun? What kind of shade? Bright or dappled? Morning sun? Can it take afternoon sun? All of this information is important to the success of your plants. But you can also do experiments here. Try your seedlings in several locations and document the results. Don’t be afraid to be a citizen scientist! 

But I’m getting ahead of myself.

Okay. You’re sitting at your table with your seeds in a little bowl. Now let’s talk about how you get the seeds from the bowl into the cells. 

Here are some seeding tools. 

The two I find of any value at all are the dibber and the tweezers. The tweezers are actually for bead work, tiny intricate bead work — kinda like seeds (they're even called seed beads!) So they work really well. I know some people use the end of chopsticks and toothpicks, but the wood is porous and likes to hang onto the seed. Actually, fingertips are my favorite tools. With many seeds, you’ll want to seed out more than one seed per cell to increase your yield of viable seedlings. But there are some kinds of seeds that are so expensive, you’re not going to want to waste a single seed. That’s when the tweezers come in really handy. 

The other seeding tools are, IMHO, completely useless. The green bubble purports to work using suction, but I lose more seeds than I’m able to plant with it. The suction loosens on the way from the bowl to the cell, and you’ve lost that seed. The other two either don’t release any seeds or WAY too many. You can try them (and you probably will) but don’t let me say “I told you so!”

So now let’s put the dibber to work. In this photo, I’m seeding out some larger seeds. 

In this case, you’ll see I’ve marked the wooden dibber in quarters of an inch so I can tell the depth. These seeds are planted at one quarter of an inch. So I went through and made holes in every cell. Then I went back, one row at a time and dropped the seed in. My method is to place the seeds in one row only, then cover those seeds. That way if I get called away to do something else for a minute, I know exactly where to start again. And sometimes those seeds are hard to see.

Which brings me to another topic. I use a sunlight lamp when I’m working. It’s on a stand and it sits over my left shoulder. I could never see what I was doing without it.  And one more little side topic: labels. I’ve tried lots of different ways to label my trays. Popsicle sticks, masking tape…..nothing worked well and often labels got lost or names of things got washed off. And popsicle sticks can get really gunky and nasty! So I use these plastic labels that can be re-used each year. Don’t use a sharpie. They fade. Terribly. Use a grease pencil. Sometimes old school is the best school. (And I trim the bottom off a bit so they fit under the humidity dome you're going to use in a minute.)

Part Three: What do I do with this tray full of dirt and seeds?

So now your tray is seeded out. I have a germination station for the dozens upon dozens of flats that I seed out every year. We’ll get into making one of those stations in another post. But the procedure is still the same. What your seeds need to germinate now is water, warmth, and light. Let’s deal with each sub-topic, one at a time.

Water: Boy howdy, has this been the steepest learning curve for me. I heard once that the quality of a gardener is all in her watering technique. It’s really that important. I’ve watered from above and below, but have settled on above. Again, if you’re soil blocking, my watering technique will probably not work for you, so feel free to skip this section. Some people water from by the bottom by pouring an inch or so of water in the 1020 tray and then letting the cells soak it up by osmosis. I used to do this. But I found that it hindered germination by often keeping the soil too moist and rotting the seeds, and sometimes the roots. Algae growth was much more of a problem with bottom watering. In addition, whenever we're propagating plants, we want to mimic nature to get the highest germination possible. In nature, in the vast majority of instances, water comes from above in the form of rain. So I water from above. 

I've used lots of different misters and nozzles and spray cans, but now I use this Haws watering can. I love the size. I use anywhere from half a can to a full can for each flat. (Have a larger can on hand to refill this small one.) What is so wonderful about the Haws cans is the watering "rose", or the nozzle on the end of the spout. It is incredibly gentle and won't wash away the tiny seeds. 

Some people water before they seed out the tray. I water after because it’s like when you water-in seeds or seedlings in the field or in the garden. You are gently firming the soil around the seed and improving it’s contact with the soil. So I water after. 

The first few days, you’re going to need to check your trays at least twice a day to make certain they are well-watered. You don’t want all your hard work seeding out the tray to be for naught. I also place a humidity dome over my tray to hold in moisture. But it MUST be removed as soon as the seedlings begin to emerge. 

Warmth: So now you have your seeded-out tray. It’s been watered and you’ve placed a clear humidity dome over it. Now place it on a seedling heat mat. I know this may seem extreme, but you MUST have a thermostat on your heat mats, even if you just have one. I’ve learned from hard experience that they tend to run a little too hot. And if the day is sunny or the room is warm, the heat mat doesn’t know it UNLESS you have a thermostat. They’re not expensive and you will be SO glad you purchased one. As you can see in this photo, I can run all my heat mats off of one thermostat. 

And lastly, light: If your mats are in a sunny window, you’re golden. I live in a log house which means heavy, steep eaves to keep the rain off the logs as much as possible. It also means less sun. So I have a germination station. 

If you want to grow under lights, the cheapest way to do it is to use shop lights that carry two bulbs. For each light fixture you want one warm and one cool bulb. This way you are mimicking the full spectrum of sunlight. It’s not perfect, but it’s close. It’ll get those babies started in a safe and protected environment. 

At this point, you continue to check, water, and wait. I can’t tell you how exciting it is to see those first green shoots and those first little bending necks of seedlings! Be sure to document when germination begins for each variety you grow. When a significant number of seedlings are up, remove the humidity dome. You’ll also want to turn down the heat or have another area to move your growing seedlings to. I move mine to the greenhouse where they stay and grow until they are ready to either be potted up to a larger cell or pot, or are ready to be hardened off, which is another topic all in itself!

Happy growing!



  1. Wonderful article, Laura! It was very informative. Thank you for sharing all this information and for all your recommendations.

  2. Thanks, Linda! And thanks for your comment!