Starting your own seeds indoors allows for more variety in your garden and is cheaper than buying plants. Following a few easy guidelines makes it simple enough for a beginner to succeed.
All the supplies that we use in seed starting are listed in Seed Starting Supplies. How important we feel our indoor greenhouse is to our success with starting seeds indoors we talk about here. How to start seeds indoors is what we want to focus on right now. Lets start with seed starting day.
Seed Starting Day
I pile all my clean and sanitized seed starting supplies on the kitchen table. Yes, we aren’t eating until this is all done. Or on the flip side, I clear the table for all my seed starting supplies so we CAN eat at the table when this is all done.
Pour about an inch or so of water in the bottom of an empty, clean tray. Fill pots or cell packs with seed starting medium and set them in the water in the tray. The water will be quickly absorbed by the soil through the holes in the bottom of the pots. You might need to add more water later in the day. The soil should be moist but not soggy. The top of the soil probably won’t be moist. No worries, we will take care of that later.
Tomatoes grow huge root systems rather quickly. We always plant them in 4-inch pots. Most of the herbs and flowers can go in cell packs.
Drop 1 or 2 seeds into the soil in each pot or cell. The tiny seeds make it difficult to tell how many you are dropping but fewer is better. As the plants grow, strong stems and roots will develop on plants that have enough room. Too many plants vying for the same space will make them all spindly.
Use a spray bottle to mist water on the top of each pot to moisten (not drowned) the top of the soil. Larger seeds like tomato and cabbage need a tiny amount of soil pushed over them. Tiny seeds like basil just want to be “watered in” by the mist.
Be sure each variety has a label. You need to know what you planted. Parsley takes 2 weeks to show any green, basil takes 2-3 days. You will never remember what it was or how long you need to wait to replant if you don’t label it. Try to put plants with similar growth habits in the same tray.
Repeat the process with each pot in the tray. When the tray is full, cover with the plastic cover or wrap the entire tray in plastic wrap. This turns each tray into a miniature greenhouse. Even though our indoor greenhouse has clear plastic sides, we still cover the trays. Trapping the moisture and keeping the soil and seeds warm adds to your success rate.
We turn the lights on in our indoor greenhouse right away. They add just a little warmth and some seeds need the light to germinate.
Check for dried out or overly wet soil. Trays should be in a warm place for seeds to germinate. We check our seedlings daily, watching for green to appear. Try to do this without removing the plastic cover. As was pointed out earlier, some seeds only take 3 days to sprout. The seed packets have this information on them. It helps a lot to pay attention to that information.
When the sprouts are tall enough to start bumping into their plastic cover, it needs to come off!
By now almost everything that we have planted has sprouted, except probably the parsley. There will be some pots that are still empty no matter how experienced you are at starting seeds. Not all seeds sprout.
Its not too late to replant those empty pots if others of that variety are up. The new plants will catch up in no time.
The plants need to be about 3-4 inches below the grow lights. Our lights don’t move so we use boxes to boost the trays to the right height. Seedlings need about 16 hours of daylight every day. They also need dark every day. We just turn on the lights when we get up and turn them off as we go to bed.
Only water seedlings from the bottom. Sometimes even misting from the top can wash out tender roots or break new stems. At this point, if the stem breaks off, the plant won’t come back. The seedlings don’t have very deep roots, however so if the soil at the top of the pot is dry, mist it. Just do it carefully, making sure there is a mist spraying. Use care in handling trays and plants.
The new seedlings need checking daily. It only takes a few minutes every day. Luckily, they don’t need as much care as chicks or puppies. You’re looking everyday to see that the soil isn’t too wet or too dry. Are the top leaves to close to the lights so they’re growing crooked or too far away so they’re spindly?
The water in the tray under the pots should get a chance to dry out between waterings but the plants should NEVER look wilted. For a long time, this is where my seedlings dried up and died. Making sure the plastic cover stayed on long enough (but not too long) and that the seedlings had adequate water made a big difference.
During these first 3 weeks, some plants will grow tall quickly. Watching everyday means that you can lower the tray (or raise the lights) as needed. Remember, the top leaves need to be about 3-4 inches from the grow lights.
Also during this time, the leaves on the seedlings will begin to change. The first sprouts are called “first leaves”. As the seedlings grow, they will develop the leaves characteristic of their species called “true leaves”. The stems will (hopefully) start to thicken and grow straight.
Somewhere around week 3 or 4, the seedlings will need to have a fan blowing on them for part of each day. There are several reasons that this is beneficial. The air movement keeps the soil from staying soggy. Soggy soil creates mildew on the top of the soil and diseases that can kill the seedlings such as damping off and root rot. The fan also helps produce the straight strong stems that will help the plants flourish and produce all season long.
If too many seeds ended up in one pot, you will need to thin the forest about this time. I use a small pair of scissors to cut the weakest smallest stems off. There should not be more than 2 plants in a 4-inch pot.
If you have any seedlings that are outgrowing their cell pack, they need to be moved to a larger pot. The stems and root systems are not very strong at this point so carefully use a spoon to lift the entire soil ball out of the cell. Try not to handle the plant or roots at all in this process.
The seedlings are growing every day. Our little shelves look like a jungle at this point. The trays need water more often now but we are still bottom watering. The root systems are so fragile.
It is now time to get the seedlings ready to live outdoors. This is called “hardening off” and it takes at least a week maybe 2 depending on the weather conditions. Be patient. Plan in advance for a sheltered spot outdoors where the sun isn’t too direct, the wind isn’t too harsh, and the temperatures don’t get below freezing. Since weather conditions change quickly, it might not work to leave your plants out while you are at work if you don’t have a sheltered spot. This is where a cold frame would come in handy. Here is a great place to learn a little more about those.
This process can take a while. For the first several days, I make sure I will be around to take trays outside and then quickly bring them inside when needed. I leave the plants in the trays for the entire process. It makes them easier to transport and keeps them watered, which is very important.
I take my trays out to the sheltered place in my back yard. Keep in mind this sheltered place also has to be sheltered from nosy animals and wagging tails. Wagging tails have broken off more of my tomato stems than I can count.
For the first couple of days, these trips outside usually only last about 2 hours. If the plants have recovered well, the weather is nice, and I have the time, the seedlings might get 2 trips in one day. Its not a big deal if its only 2 hours a day for the first couple though. I usually choose days that I am not working away from home. It’s easy to tell when it is time to bring them in because the leaves get a little wilted. As soon as they come in, they go back under the lights however.
On ferocious days, the seedlings just stay inside under the lights. That is why this process takes so long. Gradually they can spend longer outside until they are out all day. When the nighttime temps are nice, I start leaving them out overnight but not if there is a storm predicted.
When the seedlings are doing well outside, they can be planted outside. Make sure they have experienced the intensity of sunlight that is in the garden where they will be planted. After transplanting, keep an eye on them to make sure they don’t dry out until their roots start growing again.
There is a companion video on my YouTube channel here. I’d love some feedback.
This is all there is to starting seeds indoors. Good Luck and Happy Gardening!