Gardening season cannot come soon enough. We just got a fresh blanket of snow on the ground after some unseasonably warm days and I’m ready for it to melt. So many spring projects are in the works or need to be started. I need some dirt therapy. Thankfully, soon it will be time to start some of our vegetables indoors.
There are some vegetables that really thrive and transplant well when started indoors. Some… are a bit more particular when it comes to transplant time and I try to stick with direct sowing them.
Honestly, I love starting seeds indoors. I’d start them all in here if I could. It gives me the chance to work in some dirt and watch the garden begin to grow making me forget completely about the cold, wet, barren landscape outside.
8 Vegetables You Should Start Indoors
Lettuce is incredibly easy to grow. But, it doesn’t like it hot, which means starting it early indoors will help you get a good crop going before the temps soar in the summer heat.
This is a crop that can actually be grown indoors for a year round harvest, but that’s another story for another day. We typically succession plant lettuce every 2 weeks and wind up with 2 total crops a year.
Starting Lettuce Indoors
Lettuce grows quickly so I recommend using individual peat pots as opposed to the small cells in flats.
You’ll want to sow a few seeds in each container about 3-4 weeks before your last predicted frost. If you’re starting indoors, you should see sprouts in 2 to 10 days.
Lettuce seeds germinate best when the temp is about 70˚F. If the temp is 80˚F or above, they won’t germinate. And if the soil is too cold (say you’re starting in a garage or an unheated, cold greenhouse) it will take much longer for them to germinate, but they typically will within two weeks.
Place a few seeds in each peat pot filled with organic starter mix. You’ll want to sow them down about 1/4″. Water, cover them with a humidity dome and wait for them to sprout.
After a few days, check for sprouts. Remove the humidity dome once sprouts appear and provide your sprouts with plenty of light via the sun in a south-facing window or a grow light.
Thin to the best looking seedlings once they get two true leaves. Harden the plants off before you transplant them. Transplanting any start is best on an overcast day with calm winds.
Growing broccoli can be a little more difficult than lettuce, but not impossible.
This is another crop that you can get two nice harvests out of (autumn and spring), but growing it solely indoors is difficult.
It takes a decent amount of time to grow a head of broccoli, so starting it indoors while the temps are still cold and the risk of frost is still imminent is beneficial.
Starting Broccoli Indoors
Broccoli should be started about 7-9 weeks before your last predicted frost. If you’re growing a fall crop, you’ll start it indoors as well about 10 to 12 weeks before your first predicted frost.
Like lettuce, broccoli likes it cool so make sure you keep the sown seeds in an area where the temp is roughly 70°F. Leave them covered with a humidity dome until you see some sprouts. I do start my broccoli in flats and transplant them to larger pots once they develop their first true leaves before I plant them outside.
You’ll sow the seeds about 1/4″ down in organic starter mix two to a cell. You can separate the seedlings and keep them all when you pot up, if you prefer. Water and cover with a humidity dome.
Once you see sprouts, remove the dome and get them some light. Thin or pot up after all seedlings get two true leaves. Do not pull the seedlings you’re thinning. Just cut them off. Pulling them can disturb the seedlings you want to keep.
Spend a few days hardening off your plants before transplant. When you harvest, leave the plants in the ground so you can enjoy the side shoots the plants will produce in the fall.
Did you know that “days to maturity” information on your seed packet for plants pre-started indoors is indicative of how long it will take to see crop after you’ve transplanted 6 week old starts? True story. So that tomato variety you bought that says 65 days… that’s 65 days plus 6 to 8 weeks of indoor time.
Growing tomatoes is one of my favorite gardening passtimes. They can be finicky, though. They do not like it cold, at all. I typically use a heat mat to germinate the seeds because they like it hot.
Starting Tomatoes Indoors
Tomato seeds should be started indoors about 6 weeks before the last predicted frost. They love a warm environment, so while not necessary a seed starting mat or the warm top of a refrigerator can help aid in quicker germination.
I do start my seeds in flats. Tomatoes will do best if transplanted 2-3 times before they wind up outdoors, and you do not want to transplant them too early.
Sow 2 seeds in each cell about 1/4" down. Wet the starting mix, cover with a humidity dome and wait. If you have a heat mat, now is the perfect time to utilize it. They love it around 80˚F, but will germinate as low as 60˚F. I wouldn't start these guys next to your lettuce and broccoli, just FYI.
In about 5 days to two weeks, you should see some sprouts. Prop open that humdity dome, but keep it there until you see everything beginning to sprout. Once everything is sprouted, the mat can be removed, just make sure the temperature isn't going to fluctuate wherever you're growing them.
Once they have a couple of good, true leaves you can safely pot them up into larger pots. You can either cut off the seedlings you don't want to keep from the cell and transplant the whole cell or you can remove them, ever so gently, from the mixture and pot them into larger pots.
Make sure once you get sprouts that they are getting plenty of light. Leggy tomato seedlings are the bane of my existence, but they can be fixed by simply potting up deeper.
Tomatoes really benefit from hardening off, so don't skip this essential step. Like I said, make sure the soil is warm (you can prewarm your soil if you choose) and you don't want daytime temps below 70°F or nighttime temps below 50°F to make for the happiest tomatoes.
In most places, like tomatoes, peppers have to be started indoors. Their growing season is long, but most of us don't have the temps to support them.
We can prolong our growing season by beginning the seeds indoors which makes it possible for those of us in cooler gardening zones to grow hot weather crops before the temps fall back off in the late summer and early autumn.
Starting Pepper Seeds Indoors
Whether we are talking sweet bell peppers or hot peppers like jalapenos or chili peppers, it's all the same. I typically start my pepper seeds a week or so before I begin my tomato seeds.
The reason? Because peppers are notorious for taking for-ever to germinate, no matter how hot you've got that soil.
Generally, it is said to sow seeds about 6 weeks before your last predicted frost. I start mine roughly 7 weeks before, giving them an extra week to germinate. My tomatoes still typically germinate before my peppers do.
Like tomatoes, they like it hot. A heat mat or the top of your fridge is a great place to put them to make them happy. I also start these in flats and pot them up before they get transplanted outside.
Potting up plants has its advantages and generally results in stronger, more vigorous plants regardless of what it is you're growing.
Sow the seeds about 1/4" down, again. Gently tamp down that starter mix, water, put on the humidity dome and wait. It can take upwards of 2 weeks for some of the more finicky varieties to germinate. Don't be disappointed if you've started everything else and you don't see them. They're slow, but typically they will eventually sprout up.
I do have some chocolate bell peppers that I have never been able to get to germinate, no matter what I do. I've tested the germination and it's just not there like the cal wonder varieties.
Once you finally see sprouts, you can remove the humdity dome and the heat, placing a lamp over them (or putting them in a sunny window). You can pot them up once they get their first set of true leaves saving them all or removing the weaker seedlings.
Peppers also need hardened off and transplanted into warm soil. If the soil is too cold or the temps drop too much, don't plan on a very successful harvest. You'll get a few fruits, but not many. It's best to err on the side of caution and wait a bit to transplant these heat loving vegetables. Typically a couple of weeks after the last predicted frost just to be safe.
Another cool weather loving vegetable, cabbage can be helped to get amazing harvests by beginning them inside. Much like lettuce, it can be succession planted for continuous harvests until the hot weather takes over.
By starting the seeds indoors, you not only get a jump start before the soil is typically warm enough to get germination outdoors, but you can help combat cabbage worms because the larger plants are much easier to cover.
Starting Cabbage Indoors
This is another crop that does best when sown into larger, individual peat pots as opposed to cells. There again, though, anything can be potted up if you'd like to do things that way and can result in more vigorous plants.
Much like lettuce, germination rates are best when the soil is about 70˚F. You'll want to start your seeds around 4 weeks before your last expected frost.
Simply sow a couple of seeds 1/4" down in seed starting medium. Water, cover with a humdity dome, and wait. Once germination starts to occur, remove the dome, put it in some light and let it grow.
Once you start to see the true leaves form, you can thin your seedlings by cutting off the weaker plants.
Transplant the seedlings into workable soil after hardening off for a few days. It's best to transplant on an overcast, calm day.
Starting any squash indoors has its advantages. It helps with potentially devastating squash bugs when you start the seeds indoors.
Winter squash in particular can take a while to grow to maturity, so in most climates it's recommended to start them indoors. Zucchini and other summer squash grow so quickly and prolifically that you can direct sow if you want.
Starting Winter Squash Indoors
Another crop that will do best when planted in individual 2" to 4" pots, because they get fairly large fairly quickly.
You'll want to sow about two seeds in each individual pot around 4 weeks before your last predicted frost. The seeds will not germinate below 66˚F, which means by starting indoors you can help control that soil temperature and get good germination.
Squash seeds are larger, so sow them around 1/2" all the way to 1" down into the seed starting medium. Water. Cover with a humidity dome and wait for germination in about 4 to 10 days.
Once germination begins, remove the humidity dome and get some light on it. You can thin them once they begin to get their true leaves, picking the stronger seedling.
Harden off before transplanting. For best results transplant on an overcast, calm day.
If you've never started onions from seed and have always used sets, you're in for a treat. They're actually one of my favorite crops to start from seed. It allows me tons of different varieties this way.
Onions are actually really easy to grow from seed. You have to start them early, but I always have better luck with home grown seedlings than sets.
Starting Onions Indoors
Onions are usually the first crop we start inside every winter. Yes, winter, because you'll want to start these seeds about 10 weeks before the last expected frost.
Mid-February is typically when we begin them in our zone (zone 5b). Using a large container like a clamshell from berries or something similar with good drainage is best. A good 4"X6" container is the perfect size.
Fill the container almost all the way with seed starter mix. Sow two 1/2" deep lines all the way across the container. The seeds are teeny, so just sprinkle them into the lines you made and loosely cover with soil.
The onions can take a while to sprout, so like with peppers, you have to be patient. Keeping them under plenty of light and the soil moist is essential to get good germination and strong plants.
Once you begin to see germination, you can clip the greens when they're about 4 inches tall and enjoy them fresh.
You'll want to transplant the seedlings after the danger of frost has passed. Plant around four seedlings to a spot.
I know, peas are usually started outdoors, but they take quite a while to produce and I'm impatient. Also, every single time I've tried to start peas by directly sowing, I've wound up with not a single plant. Not even the slightest sign of life. So, I start my peas indoors.
We usually grow sugar snap peas, we're not big shell pea eaters, but either will be started the same way.
Starting Peas Indoors
I will preface this with this is what works extremely well for me. You do want to sow the seeds in individual peat pots or something else biodegradable because they won't take to transplant well otherwise.
Start the seeds in large, individual containers about 6 weeks before the last expected frost. You can presoak the seeds which can result in higher germination rates.
Sow two seeds in each pot about one inch down. Unlike a lot of plants, the soil temp for these should be kept around 60˚F. I don't cover my peas with a humidity dome, I just let them do their thing.
Once the peas have sprouted, you'll want to begin hardening them off and get them transplanted as soon as the soil is workable. They can handle a light frost, but you need to make sure you harden them off.
There are tons of seeds you can start indoors but these are 8 that I start inside every year. I often start others as well, but the more I can direct sow, the easier it is because I start running out of room to keep the starts under lights! Haha.
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