Starting Your Own Seeds 101


December 11, 2023

So you’re ready to try starting your own plants from seeds, congratulations! Seed starting is a rewarding skill to add to your garden portfolio. Perhaps the biggest advantage to starting your own seeds is that you now have the whole seed catalog to choose from when you plan your garden and pick your varieties! No longer are you dependent on the basics that your local greenhouses carry. Just know you should start to plan an expansion of your garden now, once you get the hang of it you’ll be addicted.

Choose the right seeds: 

Make sure to choose seeds that are appropriate for your climate and the time of year that you want to plant them. You can purchase seeds from a local nursery or online. For the best germination results you should purchase seeds that were packaged for the currently planting year. However, if kept dry and cool many types of seeds will stay viable for several years. You can check seed viability before you plant with a “paper towel test”.

Choose a container: 

There’s no end to the type of container that you can use to start seeds in. There are plenty of ideas out there for recycling and up-cycling old containers, folding newspaper pots, etc. Two pieces of advice if you choose to go this route: 

  1. Make sure your choice is non-toxic. I would stick to food grade containers or newspaper personally.
  2. Make sure your choice has drainage. Holes are much easier to make before its full of soil and plant matter.

If you choose not to recycle or up-cycle for your containers, there are a number of options on the market for seed starting kits. Of course if you’ve been purchasing your starts from a local greenhouse or nursery you may already have been saving those pots for future use – fantastic! When I began starting my own seeds I chose to invest in good quality cells and pots from Their pots are heavy duty, not the thin walled type you get from a nursery start, and they will last for years to come. I also chose to invest in their 1020 trays which fit all of their pots and have the same level of durability. I have to move my plants from my garage seed starting bench to my greenhouse, and sometimes back and forth depending on how cold it is getting at night. A durable traythat isn’t going to flex and buckle is a game changer!

Prepare the soil: 

Garden soil is not seed starting medium! It is generally too dense and heavy for fragile seedling roots. You want a medium that is light and well aerated for fragile roots. Commercial mixes are generally a peat moss or coco coir base, sometimes with the addition of vermiculite to hold water or perlite to keep it aerated. Homemade mix recipes may also have a compost or worm casting component to provide nutrients.

Plant the seeds: 

Fill your containers with seed starting medium and gently pack it. Create a hole in the medium to the depth indicated on the seed packet – I use a chopstick, a nail, a stick, whatever is handy! Drop the seed in and cover with soil, pressing lightly. You don’t want to compact the soil but good seed to soil contact is important for proper germination. 

Did you know? Some seeds need light to germinate! Lettuce is a great example. If the seed packed indicates planting at only 1/8” depth it’s a great indication that the seed may need some light to germinate.

Heat & humidity:

Seeds need warmth and moisture to germinate. If your seeding area is in a cooler place, such as mine in our garage, a heating mat may be a useful tool to promote germination. A humidity dome can also help keep the soil moist without overwatering – which can cause seeds to simply rot. If you don’t want to invest in a dome, you can use cling wrap and prop it up off the soil surface with toothpicks. Once you start to see germination it is important to remove the cling wrap or humidity dome. Too much moisture at this stage can promote fungal growth and an issue called “damping off”.

Provide Light:

Most seedlings started indoors are going to need some sort of supplemental light, either because the natural light they receive is not strong enough, or because it’s not present long enough. Simply starting seeds does not require any fancy “grow lights” that can not only be costly, but highlight the red and blue areas of the light spectrum – which are more important if you are trying to get a plant to flower and/or set fruit under artificial lighting. A quality “shop light” with a “color temperature” of between 4000k and 5000k (the range of natural sunlight) will do just fine.

What about lumens? Lumens is the rating that we use to describe how bright the light appears to the human eye. This isn’t as important a consideration as the spectrum that the light gives off – remember human eyes and plants see the color spectrum differently. I have lights that are 3,200-10,000 lumens and have had great results with both of them.

Another thing to consider when choosing lighting is the space you need to light – you may need to rotate trays frequently to make sure that seedlings at the edges of the light source are receiving adequate light or the could grow leggier than seedling in the middle of the tray.

Wind and water:

Seedlings are delicate and require the right conditions to grow into healthy plants. Maintaining the right temperature and humidity is essential, and a fan can play a crucial role in ensuring a conducive environment. A fan helps to circulate the air, preventing mold and mildew growth while also strengthening the stems of the seedlings and preparing them for their life outside. 

Proper watering could be the trickiest part of seed starting. Overwatering can lead to root rot, while under-watering can of course cause the seedlings to wilt and die. Prior to your seeds sprouting it is important to keep the soil surface moist, but not soaking. I accomplish this by using a handheld pump sprayer to gently moisten the surface without moving the seeds around from the pressure of the water. Once germination has occurred, switch to bottom watering but flooding the tray with water – drain away anything that hasn’t been absorbed in a few hours. 

How often should you water? This can be one of the trickiest things about starting seeds. You want to give your seedlings a chance to dry out a bit – by keeping soil too moist your roots will become water logged and unable to take up oxygen via air in the soil. Similarly this is why we start with small containers and pot up – if you have too much soil for a small root system it can stay waterlogged too long and drown the seedling. The environment in your seeding area will also play a roll – my seedlings in my garage and greenhouse dry out much faster than seedlings in my house where the humidity is kept higher for our comfort.

Potting up and Transplanting:

Potting up and transplanting could and probably will be a blog of its own. Before potting up a seedling the first time you want to make sure it has at least 1 set of “true leaves”. This is actually the 2nd set of leaves you will see on a seedling. The first set are the cotyledon leaves or “seed leaves” – these are actually formed within the seed! These leaves help nourish the plant through its early stages before the first set of true leaves are formed and take over the photosynthesis process. I also look for good root formation before I pot up my plants, but not being root bound. I personally want enough roots to hold together the soil the seedling is planted in.

We want to pot up to a larger, but not too large pot. Too much soil can lead to water logging and literally “drown” the plant if the roots cannot also access air within the soil. I move from a 6 pack cell to a 2.5-3” pot and then if I am potting up again in the case of tomatoes, to a 5” pot. Plants that will go out into the garden early, such as brassicas, only get potted up once. Plants like tomatoes that will not go out until mid to late May will be potted up again so the plant does not become stressed by being root bound and we can transplant the healthiest plant possible.

Hardening off:

Hardening off seedlings is a crucial step in the process of transplanting them from an indoor environment to an outdoor one, from a controlled environment to one with more variables. It involves gradually exposing the seedlings to the elements and toughening them up for the harsher conditions they will face outside. This is done by placing the seedlings outside for short periods of time each day, gradually increasing the amount of time they spend outside over the course of a week or two. It’s important to start this process at least a week before transplanting to allow the seedlings to adjust. Start with partial shade to avoid sun scald on your leaves and remember that pots may dry out faster so keep an eye on moisture levels. Hardening off seedlings helps to prevent transplant shock and gives them the best chance of thriving in their new environment.

Remember to be patient and consistent with your care for the seeds. With time and proper care, you can enjoy the fruits of your labor as your plants grow and flourish.

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