Why start seeds indoors
Starting seeds indoors is a matter of choice as well as a matter of where you live and what you want to grow. If you live in Zone 6 like I do then we don't have a very long growing season. So starting seeds indoors lets you cut down on the time to harvest and allows you to grow things that may not be possible given where you live.
Step 1 - Identify last frost dates and hardiness zone
This is very important, knowing what zone you are in can impact what perennials you plant as well it defines the length of your growing season. As with all things gardening, there are exceptions to every rule and rules are at least in part meant to be broken. So once you know your hardiness zone use it as a guide rather than a hard and set fact. Zone can change over time and they inherently average so mother nature may have her own idea about things.
Step 2 - Picking the right seeds
I use the term "right" very loosely here, by right I mean right for you. I personally choose to only use heirloom seeds as they are open-pollinated (so I can save them year over year), they have so many varieties, rich stories and taste amazing! But right for you may mean hybrids and that's fine too. Or "right" could mean only peppers or only tomatoes or whatever you eat the most! So choose what speaks to you and you can always grow something different next year!
Step 3 - Pick your growing medium
This is another choice you will have to make. There are many different growing mediums available and people have very specific ones they like. So if you are a total newb at this you will have to try a few and see what is your favourite. The one thing that is a no-no is using soil from outside. It can have pests in it and also soil-borne diseases which can wreak havoc on your new seedlings. So a good starting point is to use a seedling starting mix. Personally, I like Promix, but you can choose whichever one you like. Other options include peat pellets (like Jiffy), coco coir, vermiculite or even potting soil.
Step 4 - Choose your containers
It may seem like the choices are endless, but here is one more, the last one for now. You will have to decide what you want to grow your seeds in. There are many options again, so the choice is yours. If you chose peat pellets in step 3 then your choice of container is already made for you. If not then you will need to make sure that whatever container you choose has good drainage. You could make your own paper pots, use toilet rolls, solo cups, little plastic pots, peat pots, grow bags or seedling trays. I would not recommend eggshells or eggshell cartons as they are quite small (and very hard in the case of eggshells) and don't allow for a lot of root growth.
Step 5 - Watering
You may be wondering why watering is the next step before actually planting the seeds and I wouldn't blame you. But I assure you there is a reason and I'm just about to reveal it to you. It is best to completely wet down your growing medium before you add your seeds. In the case of coconut coir or peat pellets they will have to rehydrate. For seedlings starting mix or potting soil your seeds will stand the best chance of staying where you plant them if the mix is wet and a bit compacted. After this initial wetting of your chosen growing medium, your seedlings will be best served if you wanted them from below. So having a tray to keep them in where you can pour water is helpful. As an added bonus this tray will come in handy when we get to step 8.
Step 6 - Sow your seeds
When sowing seeds, depth is everything! Most seed packages will tell you how deep to plant your seeds and it is important to pay attention to this. If you plant your seeds too deep then they may not sprout as they could use up all their energy before they are able to get above the soil. A rule of thumb is to plant the seeds twice as deep as they are wide. So a pea seed is going to need to be planted much deeper than say a basil seed. Once they are planted cover them lightly and carefully wet the top, you can use a mister or spray bottle but I would not recommend using it after this one time. As I mentioned above bottom watering is best.
Step 7 - Warmth & Light
There are many ways to achieve this and they range in price. The cheapest way is to put your seedlings on a south-facing windowsill. This may lead to your seedlings getting a bit leggy (tall and skinny as they stretch for light) but it can work in a pinch. The more expensive and some would argue "better" way is to invest in a grow light and heat mat. If you have to choose one of the two I would always pick the grow light. You want to keep the light 4-6" from the top of the seedlings. If it is too far away they can start to get leggy. A heat mat is a definite bonus to help speed germination but it is not a must-have.
Step 8 - Harden them off
This may be the most crucial of all steps. Skip this one and all your hard work may end up being in vain. Why? Well, your wee plant babies will not be well equipped for the outside world after being started indoors. They need to be gradually introduced to the outdoor elements so that they may learn to thrive in them. This introduction needs to be slow so that they can adjust. Hardening off your seedling is not a hard process, except in terms of discipline. So it is crucial to rein in your enthusiasm and take the 8 days to fully allow this process to be completed.
I find it best to keep them on a tray so it is easy to move them in and out each day. I Can't emphasize enough how important it is to set an alarm each time you move them outside. There would be nothing worse than to get sidetracked and forget to bring them back in on time! I have outlined my process below which has worked for me for years.
Day 1 - On the first day, you are going to want to keep them in the shade and protected from the wind. Bring them back inside after 3 hours.
Day 2 - Today they can have a bit more light, but most of their time outside should still be in the shade. Bring them back inside after 6 hours.
Day 3 - Today is the first time they can have a bit of direct sun but only a bit. Bring them back inside after 9 hours.
Day 4 - They can now be less sheltered and have access to a bit more sun. Bring them back in after 9 hours.
Day 5 - This is basically a repeat of day 4 except that it can include 1-2 hours of direct sunlight. Bring them back in after 9 hours.
Day 6 - During the day they can have even more sun and as long as the temperature is not projected to drop too low then this can be their first sleepover outside.
Day 7 - Today they should get sun most of the day and can stay out all night again.
Day 8 - Today is the big day! It is FINALLY time to plant your seedlings outside. Make sure to water them well once they are planted.
Go forth and grow many happy, healthy and strong plant, babies. It is so rewarding to grow your own food. You won't get any fresher than freshly picked from your backyard! It is amazing to taste the difference between the grocery store and homegrown vegetables!
