A Beguinner's Guide to Seed Starting
Updated: Mar 9
Whether you’re interested in growing lettuce in a pot to save a few bucks, or turning your entire yard into a florist’s dream, there are bound to be some helpful hints here for you!
Step #1: Plan
This part of the process is either the most or least exciting, depending on your personality. Sitting down and making a solid planting plan will not only help you organize your upcoming growing season, but it will help to ensure you don’t buy too many – or worse, too few – seed packets. The first step is to measure your garden, or at least your garden beds. This doesn’t need to be accurate down to the last millimetre, but make it as close as you can. The same applies to those growing in pots or raised beds. It’s important to know how much space you really have. Make note of which area of your garden in the sunniest, and which is the shadiest. Your sunniest locations should be reserved for things like tomatoes, peppers, melons, zinnias, dahlias, sunflowers, Mediterranean herbs…anything that says full sun on the back of the seed packet. Any areas that would be considered partial sun or shade should be reserved for leafy crops, such as lettuce, spinach, any Asian greens such as bok choy or pak choi, and leafy herbs. Draw a simple blueprint of your garden on paper, making sure to write down the dimensions of your garden beds. Write the sun exposure on each garden bed, from full-sun to shade. If you’re in a new garden, or just aren’t sure how much sun you’re getting, assume that everything is partial-sun for now, but be sure to make notes about your light levels this coming season.
Step #2: Decide What You Want to Grow
Now that you have a general idea of your space and sun exposure, it’s time to think about what you can grow. This decision should be based solely on two factors; what you like, and what will thrive in your conditions. If you’re looking to grow fruit and vegetables, choose things that you like to eat. If you’re growing flowers, think about what you want them for. Cutting flowers to bring inside the house? Or wild ramblers that will spill over the side of your pots? I know this seems incredibly obvious, but you’d be amazed how many beginners reach for a packet of runner beans just because they’ve been told it’s an easy crop…yet they don’t like beans at all. So, come up with a wish list, organized by your growing zones. You don’t need to decide on any specific varieties at this point. The most important thing is that you keep your growing space in mind. Large plants, such as tomatoes, peppers, zucchinis, and head lettuce, need approximately a square foot of space around them in order to grow well. Flowers, root crops, and smaller leafy greens need less space. Getting the exact spacing right comes down to experience, so for your first few seasons just remind yourself – bigger fruit, bigger space.
Step #3: Choose Your Seeds
I think this is the part where a lot of beginners get overwhelmed, and for good reason. We are absolutely spoiled when it comes to seeds, as there is often considerably more choice than there would be if we were buying veggie starters or trays of annuals. But fear not! Arm yourself with your list, and read the seed packets carefully. All seed packets should have an indication of the light levels the plant requires, the amount of time it takes to be fully grown, the spacing it requires, and there is also usually an indication of whether to sow the seed directly outdoors, or if it can be started inside. If you’re growing in containers, look for varieties that have been specifically bred for container growing. This is typically either indicated in the name (Spacemaster cucumbers, for example), or by a symbol of a pot on the back of the packet. If you would like to try saving your own seeds, you should be looking for heritage and organic varieties. If you see “F1” or “F2” on the back of a seed packet, it means that the plant is a hybrid, so any seeds you save are unlikely to grow a plant exactly the same as the ones in the packet. However, hybridized varieties are often more resistant to common diseases and issues associated with the plant, so they are often a better choice for the true beginner. And feel free to ask for advice at this point, either from staff or from someone else who may be choosing their seeds with slightly more confidence than yourself.
Step #4: Choose the Right Starting Materials
The one thing I would strongly suggest all beginners get is a seed tray. This is a black plastic tray with a clear dome. These are useful for two reasons. One, the tray doesn’t have drainage holes, which is ideal for seed starting. Ideally, you should be bottom watering your seeds to prevent them from “rotting off”. And two, the clear plastic dome holds in heat and humidity, two things that your seedlings will require when they’re very small. Now, onto the actual containers your seeds will be in. Again, you will find an abundance of choice here. There are strips of dehydrated “pucks”, designed for a single seed; there are seed starting cells, which are reusable plastic trays, there are small individual pots, seed trays, and of course, containers pulled from your own recycling bin. If you want to use the latter, remember to make drainage holes and to thoroughly wash the containers. Disinfect with vinegar if possible. The containers you decide to use should be based on the seeds you’re growing. For example, any “hot-house” plants such as peppers, tomatoes, and dahlias need a longer time to grow before they’re ready to go outside into the garden. So rather than fussing around with repotting every month, I would suggest starting these seeds in 3-4 inch pots. Sew a few seeds in each, and once they start to develop their true leaves (these are the leaves that actually look the way they will look on the fully grown plants, seed leaves typically look like a bubbly cartoon heart or a simple tear drop), choose the strongest seedling and carefully remove the others. These will not fare well if you try and repot them, so throw them into the green bin. Flat seed trays with drainage holes are great for sewing herbs and leafy crops, while seed cells are ideal for most flowers, head lettuce, and basically anything other than trailing vine plants or root vegetables. The dehydrated pucks work well for large seeds, like beans or sunflowers, as it’s easy to make sure you’re only sewing one seed in each.
With your vessels chosen, it’s time to move on to soil. This is perhaps the most important step, as the quality of the soil determines the strength of your seedlings. Always check the ingredients on bags of soil, but most especially on those marketed for seed starting. If the first ingredient is top soil, or if there are any added nutrients or fertilizers, do not buy it. If there is a chemical smell coming from the soil, do not use it. Your seedlings do not require any additional nutrition or fertilizer when they start out, as they have everything they need to grow right there in the seed. When you start repotting your seedlings as they grow stronger, then normal potting soils can be used. But most regular potting or soil mixes are too heavy for seeds to germinate indoors.
As a final note, I will mention things like UV lights and heating mats. If you’re just starting out, these aren’t really necessary. Don’t be tempted to go down a rabbit hole of niche seed starting tools and spend a fortune – all you need is a sunny, warm window. If you’re concerned about the light levels available for plants that must be started very early, such as perennials, a grow light screwed into a directional desk lamp is enough to give them a little extra boost.
Step #5: Getting Started
With your bounty of supplies in hand, it’s super tempting to start right away. But it’s very important to get the timing right when it comes to seed starting. So, sit down with your seed packets, and organize them by the suggested starting date/method. All the seeds that should be sewn directly outside, like carrots and poppies, can be their own pile. Make another for your slow crops, which are any that should be started 6-8 weeks or more before the last frost, and yet another for the quicker ones, the 3-5 week crowd. Now, I know what you’re thinking at this point – how do I know when the last frost is? Well, the answer is that no one can know for sure, so we just have to make an educated guess. For the 6-8 week seeds, I typically start mine the week after Valentine’s Day. For any faster crops, the timing is less important, so you’ll be fine starting them anywhere from mid-March through April.
Pull out your planting plan. Decide at this point which seedlings will be going in which beds, and how many approximately you have room for. I typically add a few extra to this number, as there will always be seeds that don’t germinate, or seedlings that die. This is especially important for any of your seeds that must be started early. It’s far better to have too many healthy plants that can be given to friends, than to have too few.
So, let’s jump ahead to when we actually start sewing our seeds. I like to dump my seed soil into a large bowl and thoroughly moisten in first. This not only makes the soil much easier to handle (and makes cleanup easier for you, as good seed soils are often also pretty dusty), but it means you won’t have to water afterwards, which can sometimes dislodge the seeds. Fill your pots and seed trays almost to the top, pressing the soil down lightly to ensure there are no air pockets. Please note, you do not want to compress the soil at this point, as it will make it more difficult for the seedlings tiny, fibrous roots to get in there. The biggest mistake people make with seeds is sewing them far too deep. Light and moisture are what tells a seed it’s time to wake up, so if you sew it too deeply, it is less likely to germinate. For any seeds that are too tiny to handle individually, such as herbs, poppies, or lettuces, pour some out into the palm of your hand. From there, take a small pinch and sew them carefully and thinly on the top of the soil. Larger seeds, such as beans or nasturtiums, can be easily handled individually, so feel free to be more precise with your placement and push it into the soil slightly. Also worth noting, any seeds that appear “flat”, like cucumber, melon, or sunflower seeds, should be put into the soil vertically rather than laid flat, as excess moisture can pool on the top and rot the seed. With your seeds in their containers, the next step is to lightly cover them. This can be done with the rest of your soil, perlite, finely crushed pumice stone – the most important thing is to ensure that your seeds are thinly covered. Now, using your fingers or the back of a spoon, gently press down on the surface of the soil, to ensure your seeds are fully in contact with the soil. At this point, it is crucial that you label. Using either reusable plant labels or wooden popsicle sticks, write down the name, variety, and the date the seed was sewn. This is not just to ensure that you don’t plant things in the wrong place in the spring – it’s also to help you keep track of start dates, failures and successes in coming years. After that, it’s up to you to keep your seedlings evenly moist, not soggy, and to ensure they’re growing strongly by rotating them occasionally. And remember, whenever possible, avoid watering your young seedlings from above. Pour water into the tray they’re sitting in, and allow them to drink from the bottom. This will encourage stronger roots, and help to prevent the seedlings from rotting off. You may need to repot your seedlings as they mature.
Step #6: Hardening Off
In our climate, this step is an important one. Hardening off refers to the gradual act of acclimatizing your seedlings to the conditions outside. My tip as a long-time vegetable grower is to get your seedlings outside as soon as the daytime temperature is above 5 degrees. Yes, I know that seems far too cold, and yes, they will need protection at this point. But compared to outside, our houses are incredibly dark. Even with the aid of grow lights! So, get your baby plants outside as soon as the weather allows. If you’re crafty, and have the space, look into building a cold frame. Tutorials on how to build them can be found all over the internet and in gardening books, in a wide range of difficulties and price points. You could also invest in a small, greenhouse shelf that can easily be taken apart and stored over winter. If none of these options appeal, head to your nearest big-box store and pick up the largest clear storage container they have. With a drill, make a couple dozen holes in the lid for air flow and drainage, as this is going to be the floor of your tiny greenhouse. Then, all you have to do is choose a spot that is partially sunny, not full sun, bring your seedlings outside, and cover them. Please note, at this point it will be too cold to leave your seedlings outside overnight, even with protection. This step is really a labour of love, as your seedlings will need to be monitored to ensure they’re not drying out or being exposed to too much sun. I typically only put mine outside on days I’m not working at this point, so I can check on my seedlings throughout the day.
Continue this until springtime temperatures are at least 12 degrees during the day, and a few degrees above freezing every night. At this point, you want to uncover your seedlings, and leave them outside permanently, unless there is a frost risk. Being exposed to wind, rain, and anything else the spring can throw at them will make your plants stronger, and is the final step in hardening them off. If you’re unsure of when it’s time to plant, just remember – if it’s warm enough for weeds, it’s warm enough for seeds. When the weeds start popping up, you’ll know the soil is warm enough for germination, and you can finally sew all your seeds that need to be started directly outdoors. Take a look at the coming forecast at this point. If the weather is cooperating, plant out the rest of your hardened off seedlings, but be prepared to cover any sensitive vegetable like tomatoes and peppers for the coming weeks.
If you’ve been interested in growing from seed for a while, and have been looking at the internet for inspiration, you’ve probably encountered the concept of “succession planting”. If you’re a beginner, please don’t worry about this. It takes years of experience, and mistakes, to learn how to properly plan for something to be harvestable in your garden from the first frost to the last. For your first few years, you can “cheat” succession planting by simply sewing seeds alongside your seedlings when you plant them. For example, when you plant your head lettuce or runner beans, if you sew seeds alongside them, you will have a staggered crop. This will allow you to harvest for a longer period of time.
For anyone wanting to grow flowers for cutting, chicken wire, nets, or grids made of twine and bamboo stakes are your best friend. Secure one of these about a foot off the ground, and as your flowers grow, it will both ensure the stems are straight and act as a support, saving you a lot of staking for heavy flowers like dahlias and delphiniums.
There is a lot of misinformation out there about the shelf life of seeds. With very few exceptions, such as onions, most seeds will store for several years and still be viable. Store them in an airtight container, in a cool and dark place, and your seeds will keep for years. Just note, every year the rate of germination will slightly decrease, so you will have to sew more to get the number of plants you want. But hey, waste not want not!
If you find an old packet of seeds that you forgot in the shed, and want to know whether they’re viable or not before you go through the rigamarole of planting, try the paper towel trick. Thoroughly wet a paper towel, and lay it out flat on a plate. Lay a good sample size of your seeds, at least 3, on the paper towel. Put it somewhere bright and ensure the paper towel remains moist. If the seeds are still viable, you should see green within a couple weeks. If nothing happens, it’s safe to assume the seeds are dead, and the packet needs to be replaced.
My final note is that growing from seed, like all gardening, comes with a learning curve. When you first start out, you’re likely to have some failures – and that’s okay! By taking the time to plan properly and understand your growing space, you will already be avoiding many of the mistakes beginners make. Even if it’s a true disaster, you will have learned something, and will be a savvier gardener next year. And remember, the beauty of growing from seed is that it’s inexpensive, so you can try as many times as you need to get it right.