Growing from seed is a numbers game. For every seed you sow, only a certain number of them are likely to sprout. And because seed starting space is often very limited, gardeners want extra insurance to know that they will have the right number of baby plants to grow on. What do we do? Multi-sow!
Seeds are abundant in nature and also in seed packets you buy. So, instead of planting one seed per cell, you plant 2-3 seeds in one spot. Your goal is that one of them will sprout. And you do a happy dance when that happens. However, more often than not, you'll have more than one of those seeds pop out of the soil, which brings us to today's discussion: thinning.
It's incredibly important to thin those tiny sprouts so that they can grow up into healthy plants. As those clustered seedlings grow, their roots will compete for water, leaves for light, and soon instead of a cluster of healthy plants; you'll end up with weak, leggy, and unable to thrive starts. When this happens in nature, the strongest seedlings prevail, and I guess you could take that approach, but really, this task is simple, and we're after the strongest plants possible.
Now that you understand the why, let's talk about the how. How do you thin your seedlings? There are two ways to do it. You can either snip out the extra plants or "prick" them out.
Snipping is exactly as it sounds. You take a pair of scissors, choose the strongest seedling in the bunch, and cut out the rest. This method is perfect for those who grew multiple seeds per tray, knowing they only have room for so many plants in the garden. It's quick, easy, and in the case of greens, you suddenly have a bowl full of microgreens to munch on. Early harvest! Another reason to choose snipping extra seedlings has to do with roots. Some plants, like sweet peas, do not like their roots disturbed, and trying to separate them can result in stunted growth and weak plants. It's just not worth it. I would definitely recommend snipping most of the time, but pricking out has its place.
Pricking out is the process of gently removing the seedlings from their pot and ever so gently teasing apart their roots. This method is definitely more labor-intensive and time-consuming, but it has upsides too. For example, sometimes you have spotty germination, and instead of having empty cells in your trays, you can tease apart a clump and spread them out to fill in all empty spots. Or maybe you have a very limited supply of a certain seed, so every sprout is worth saving.
This winter, I sat down with Karen Hollingshead of Hilltop Hygge Homestead from Ontario, Canada, to chat about her Grandfather's precious tomato seeds. He had a favorite variety of sauce tomato called Bonnie Best that he grew year after year from the 1940s until his passing in the '80s. Those treasured family heirloom tomatoes were gone as far as the family knew. But then a small bag of seeds was found a few years ago in a junk drawer, and Karen decided to plant them. Those decades-old seeds sprouted! And now Henry's legacy lives on through his Granddaughter's green thumb. Karen shared a small packet of those Bonnie Best tomato seeds with me, and I can't wait to bite into the first one this summer. It's a great story, so grab some tea and a cozy blanket. You can watch our conversation here. So, there will be no snips allowed near my tomato seedlings!!! Every Bonnie Best is going to be given a chance. You can catch that interview on Instagram: https://www.instagram.com/p/CXR4_yrpYc4/
When it comes to thinning, my personal preference is really a combination of many methods. This year, I am moving to use soil blocks and have invested in a 2" blocker and a 3/4" mini blocker. The goal is not to do any thinning for the mini blocked trays, and most of those seeds are sown one per block. But then microgreens are a must, and I do sow multiple seeds for brassicas and edible greens. Those I happily thin by snipping. I'm also trying to germinate Statice seeds I was given that are dated from 2010. Since those seeds are quite old and unlikely to sprout, I planted 4-5 seeds per mini block and would be super excited if even one germinated. If I get a few clustered, I'll divide them. But if I see good germination by some miracle, I'll snip out the extras. Statice, also known as Sea Lavender, is a favorite cut flower I use in bouquets. Fingers crossed they sprout! I had a mouse get into my seed starts, and it ate all of the Statice and lettuce seedlings I had already growing. Sigh. Round two.
Have I pricked out plants this season? Yup. I started a bunch of Johnny Jump ups, and since it was a new to me seed, I multi-sowed the cells. Some came up in clusters, and some did nothing. I think I only divided two cells and was able to fill in all of the gaps. The rest I snipped out. In that case, I had a clear number of starts I was aiming for, and that was it.
It's really easy to see all of those baby plants and feel like you need to save every single one. They grew and deserve a chance to live, right?! Bring on all of the plant-loving feels! I have absolutely been there. But what can happen? A few years ago, I sowed an open tray of basil and ended up with over 100 seedlings. I was so excited that they grew (new seed starter kind of wonder) that I pricked out every one of them. Did I have room for 100 basil plants? No. And what happened was I devoted my energy to growing that one abundant crop instead of starting other seeds that I did want to grow that year. I didn't have a plan.
Here are my parting tips for you, garden friend. When you are sitting with your beautiful tray of sprouts and trying to decide whether to snip or separate, keep your garden goals in mind and grow with confidence. You'll figure it out. Or, if you've never tried one of these thinning methods, I encourage you to give it a go this spring. These are garden skills that are good to have and worth mastering. You might discover you have a knack for growing and pricking out kale and are suddenly able to donate starts to a food bank or help fill a friend's raised beds. You never know how or when you'll be able to use your garden to bless your community. I hope you do!