Learn all about seed starting! We're serving up some listener questions around soil, grow lights and the best seeds for fast germination. You’ll also learn when to transplant your veggies and if you should start growing them indoors or outdoors.
Learn all about seed starting! We're serving up some listener questions around soil, grow lights and the best seeds for fast germination. You’ll also learn when to transplant your veggies and if you should start growing them indoors or outdoors.
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Find episode transcript here: https://dig-it.simplecast.com/episodes/seed-starting
[MUSIC PLAYING] KELLY SMITH-TRIMBLE: Hi. This is Dig It! I'm Kelly Smith-Trimble. I'm a master gardener and the author of Vegetable Gardening Wisdom. I'm also the senior editorial director at hgtv.com. In this episode, it's all about seed starting. We've got some listener questions about soil, grow lights, and the best seeds for fast germination. Let's dig in.
Rebecca says, "I'm growing veggies from seeds. When do you plant them in a raised bed?" So what you need to figure out, Rebecca, is your last frost date. That's when you can move seeds that you've started inside, outside. And that's usually warm season plants, like these tomatoes here. So look for your last frost date in your area. It differs depending on where you live. And that's when you can start moving those seedlings from inside to outside.
Megan asks, "Is it advisable to start root vegetables, specifically carrots and potatoes, from seed indoors? I feel like transplanting them will disturb the root." So I think you should trust your instincts there. You can start root vegetables indoors and then transplant them outside, but I find it's really just easier to seed them in place where you're going to be growing them outdoors.
You may end up needing to thin them, particularly carrots, radishes, and beets, after you seed them because they seed really closely together. And that basically just means picking out a few of them so that the rest of them can grow.
Cindy said, "I keep buying seeds for herbs, but the only ones that grow are parsley, basil and dill." So it may seem cheaper and easier to grow herbs from seeds, but many of them don't grow that easily from seed. So I usually buy transplants instead, and that's what I recommend, like basil and thyme.
Some exceptions are cilantro and dill. Those grow really easily from seed. But for things like sage, rosemary, those are woodier plants. Definitely start with transplants for those.
Now my co-worker, Marianne, has a question about saving seeds.
MARRIANE: Hey Kelly. Say you have a fruit or vegetable you are particularly obsessed with, like this King of the West Honeydew.
SPEAKER 1: Yum, yum, yum.
MARRIANE: What's stopping me from--
SPEAKER 1: [INAUDIBLE]
MARRIANE: What's stopping me from saving the seeds and trying to grow them myself next year?
KELLY SMITH-TRIMBLE: There are a few reasons not to save seeds from grocery store produce. One is that even though it sounds crazy, some seeds are intellectual property. And so you're not legally supposed to replant them. But the bigger reasons are botanical, not legal.
Mature seed for saving is best taken from over-mature plants or fruit. Another reason is that a lot of grocery store varieties are hybrids, which means that when you plant the seed the following year, you may not get exactly what you had originally. All that being said, though, you could always plan it and try it.
Josh is starting his summer plants from seed indoors and asked, "Do you have a favorite mix for re-potting? My seedlings are ready to move up from their starter pods." I've recently been using this seed starting potting mix and I like it a lot. I wasn't sure at first, because it does have larger chunks of organic material than I'm used to in a seed starting mix. But it seems to hold water really well and not dry out as quickly as other mixes.
I'm stepping up some of my seedlings into larger pots too. I've been saving plastic containers to reuse for potting so I'm not wasting so much plastic. If you try this too, just be sure to poke lots of holes in the bottom for good drainage.
Leanne says, "I have some seed packets that I got for free, but they say 2019 on them. Will they grow?" And my answer is, probably. You might as well plant them and see. These seeds are probably fine. If they were a couple of years older than that, maybe not, but I would tell you to plant those too and just try it.
I've seen a few questions about growing indoors. Most of us don't have greenhouses, so there are some good tabletop or kitchen counter-top kits that you can try. I really like Aerogarden, which is a hydroponic growing kit. It grows really well. It's good for anyone, but it's especially fun to grow with kids. My nephews, Henry and Pete, are actually growing herbs and they want to tell you how it works.
SPEAKER 2: In the Aerogarden, we are currently growing thyme and curling parsley, a little bit of mint, two different kinds of basil, and the dill that is currently taking it over. You might not see it, but there are actually a ton of roots. There is some plant food and water.
And these plants go in there and collect all that. And then this light will be on for like 12 hours a day and off for 12 hours a day to make it so that it's like it's actually growing in the sunlight. So that's how our Aerogarden works.
KELLY SMITH-TRIMBLE: Thanks guys. The Aerogarden really is great for growing herbs like you guys are doing. But I've also tried some tiny varieties of tomatoes and peppers and those do pretty well too.
Deanna asked, "What kind of dirt should I use?" So when you're starting seeds indoors, you want to use something called seed starting mix rather than regular soil. It's really fine textured, which is good for new roots. It's also free of mold or fungus, which could damage baby plants. Seed starting mix is made out of peat moss, vermiculite, perlite, and a little bit of compost. As the seedlings grow, the compost provides nutrition.
Kim asked, "Should I start anything from seed indoors or wait until March?" And she's in zone seven. Starting seeds indoors is not a necessity. You can certainly wait until spring and start outdoors. But it can be a fun project to do indoors during the winter. It's especially important in colder climates where you have a shorter growing season. So it gives you a jump start on spring. In zone seven, you have a longer growing season, so you can certainly wait.
Michelle asked, "Do I really need grow lights and heating mats to start my seed?" If you're starting seeds indoors, I highly recommend using grow lights and heating mats. Unless you have a really warm home and a spot with tons of direct sunlight, you're not going to have as much success without using these items.
When you're starting seeds, it's usually recommended to keep lights on for 16 hours a day and off for just eight hours a day. You can ensure this by putting your lights on a timer.
Mike asked, "Which seeds are best for fast germination?" Germination is the process of a seed becoming a plant. And the term sprouting is basically the same thing. Germination time depends on many factors, including temperature. But there are a few plants that typically germinate in one to two weeks, which is pretty fast, including beans and peas, radishes, melons, and squash, corn, and some greens like lettuces, and arugula, and mustard greens.
Kristen has a good question. She says, "What do I do when seedlings get leggy?" The term leggy describes seedlings that have a long, thin stem and they sometimes will flop over. And that's because they're stretching, literally stretching to try to find light. It's more likely that your light source isn't bright enough or not on long enough.
If your seedlings are leggy it could also be that you seeded them too closely and you have too many plants in one cell. You want to go in and remove some of the plants to make sure that they're not competing for sunlight. That's called thinning. And you can do that with small scissors to help remove the plants without disturbing the roots of the ones that you keep.
Now you can always wait and start your garden from transplants that you buy at the garden center. But if you do plan on using seed, I really recommend going ahead and ordering your seed soon. Last year a lot of seed companies sold out really quickly and it'll probably be the same this year.
I get my seed from a variety of companies. One important tip is to look for seed that is labeled either widely adapted, which means it grows well in any region, or seed that is specifically known to grow well in your region.
Another tip is to use the information provided to you on the seed packets. It's there to help you. One thing you can really look for is information about timing. For example, it says to plant these shishito pepper seeds indoors six to eight weeks before the planting date outdoors, which is the last frost day. It also gives the optimal temperature for germination, which is 75 to 85 degrees.
Tammany said, "What is the best way to transition seedlings to the outdoors?" So if you're starting seeds indoors, you're working in a very controlled environment. You're controlling the heat and the light, and you're moving your seedlings outdoors to an environment that you can't control. So you need to do this really gently and you need to acclimate the seedlings to the outdoor conditions. And this is called hardening off.
After your seedlings are a good size, large enough to transplant, take them outside a little bit at a time, starting with an hour a day and gradually moving up to all day. You can just move a whole tray out and back daily. Just be mindful of heavy winds or rains in the forecast, because you want to ease your seedlings into the outdoors. After your seedlings are hardened off you can transplant them outside.
Laura asked, "When should I start my seeds for fall plants, like cabbage, broccoli, cauliflower, and brussel sprouts?" You can start those indoors and then transition them outdoors when the temperatures start to drop to the 60s and 70s. You can wait a few weeks to start crops that don't take as long to mature and sew those directly outside. These include root crops like beets, turnips, radishes, and carrots, as well as greens, like kale, collards, lettuce, and arugula.
For more gardening info tips, and hacks, check out hgtv.com/digit. I'm Kelly Smith-Trimble. Happy gardening.
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