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How do you turn that packet of tiny basil seeds into pots of lovely herbs for your garden? Starting plants from seed seems like a magical process, but there’s no great mystery to it. A few tips and pointers will help you on your way…
You've set up light shelves and heat mats. You've sterilized your seed starting mix and considered other tips to prevent damping-off. You've ordered seeds for more plants than your yard and your neighbors' yards together can possibly hold. You are more than ready to start turning your seeds into rows and pots of healthy seedlings!
Although it's possible to sow seeds one by one into little pots on your light shelf, many plants seem to do better when transplanted once between sowing and being planted out in the garden. I usually start seeds in rows in shallow, domed seed starting trays. After the seedlings have their first true leaves (the first pair of leaves are cotyledons, or "nurse leaves"), they are potted up into individual pots or cell packs. For plants with a naturally branching or clumping habit such as basil or lobelia, I use a method that herb guru Tom DeBaggio calls "clump transplanting."
You can purchase official "seed starting trays," often with vented domes to hold a little extra humidity around the seedlings. Or you can create your own, using any container that will hold a good inch or so of potting mix. Take-out containers work great! Poke a bunch of holes in the bottom for drainage and in the top for ventilation. A hot metal skewer works well to make holes in a dozen nested containers at once. Separate containers after each jab so they don't "weld" together. Be careful, and work in a well ventilated area.
Basil seedlings in closed vented container. Note little puff of condensation in lower left corner.
Use a good soil-less potting mix. If it's not a "seed starting mix" as such, you may want to lighten it with a little extra perlite. I also add a pinch of polymer moisture crystals to my mix, so I don't have to water as often. Fill your seed starting container with moist, preferably sterile mix. [1]
Petunia seedling tray, aka salad container. Droplets of condensation inside lid indicate too much moisture in potting mix.
Sow seeds in rows at least an inch apart, so that a row of well rooted little seedlings will be easy to break away. I sow seed quite thickly for clump transplanting. There's generally no need to cover seeds; just press them gently into the surface of the potting mix. Don't forget to label the container using a permanent marker or paint pen. Jot down the date also, to keep track of germination times.
When the container is closed, there should be enough humidity to make a little puff of mist on the inside of the lid. If large droplets of condensation form, then your mix is too wet -- prop the lid open for a few hours to let it dry out a bit. The container can be easily watered from the bottom as needed. Place it in a tray of water for a few minutes, until it no longer feels lightweight.
At the first sign of germination, I make sure my seedling tray is as close as possible to the fluorescent light tube.[2] When seedlings have their first true leaves, and for sure by the time they have their second set of true leaves, they are ready to be transplanted. Looking at the seedling tray from the bottom, you can see vigorous roots searching for more growing room.
Tom DeBaggio's clump transplanting method [3] makes for healthy, sturdy seedlings. It's very simple. You don't tease away a solitary seedling from the massed rootlets in the seedling tray. Instead, you gently separate a clump of seedlings and plant them together.
Having a larger clump of roots in the pot means it's harder to drown the little seedlings. Damping off issues of root and stem rot are less likely when there are more roots to take up more water. With plants like basil, seedlings clumps give you a nice, full appearance before you even start pinching back the stems.
Tom recommends 3 or more plants in a clump. I've had young friends who enthusiastically potted up huge clumps of basil seedlings, and others who carefully selected a perfect pair. It's all good. In Tom's words, "I don't count them, but take what comes apart most easily with the least root damage. It would defeat the beneficial effects... to prick out individual seedlings and gather them in clumps... the larger the leaves, the fewer seedlings [should be] in the clump."
I like transplanting to pots no smaller than 48 cell inserts for standard nursery flats. Most of my seeds are started 6 to 8 weeks before planting out. Seedlings that will be started sooner (like wave petunias) or grow larger (like tomatoes) get a 2 inch pot. Fill pots or cell packs ("sheet pots") with moist potting mix, and poke a hole in the mix with a stick or with your finger.
Handle seedlings by their leaves, and gently massage their roots to separate them into clumps. The tender stems should be touched as little as possible. Here's Tom's other piece of invaluable advice: "Set the seedlings into the pot lower than they were growing in the seedling flat," preferably with the true leaves level with the growing medium and the cotyledons (nurse leaves) covered.
Gently pat the potting mix around the seedling clump. Water carefully around the seedlings to settle the potting mix around the roots. Your newly transplanted seedlings are ready to go back on the shelf, very close to the lights for best growth. After several more weeks, they will be ready for hardening off and planting out in your garden.
Sowing and transplanting is a straightforward, two-step process. There's no "one true way" to go about it, but using covered seed starting trays and transplanting with Tom DeBaggio's clump method definitely works for me. Before you know it, you will have turned a few seed packets into flats of beautiful seedlings for your garden!
[3] I owe a great debt to Tom DeBaggio and his "little book" that made me believe I could succeed in starting basil and other plants from seed. See my review in Garden Bookworm.
DeBaggio, Tom. Growing Herbs from Seed, Cutting & Root: An adventure in small miracles. Interweave Press, 2000. ISBN #: 1883010780
About Jill M. Nicolaus
Better known as "Critter" on DG, Jill gardens in Frederick, MD. The weather is heating up, and I'm trying to catch up on planting and transplanting. Between the plants enjoying the protection of the deck canopy and those on the patio waiting to be planted out, it looks a little like a nursery right in our own back yard! I love it, and DH is patient with it as long as he can get to the grill... (Images in my articles are from my own photos, unless otherwise credited.)
Posted by ivesco (from Monterey, MA) on March 23, 2008 at 5:31 PM:
By mail order, I've received cells crowded with foxglove seedlings, but there is still snow on the ground in my zone 4a woods. Should I transplant the seedlings in clumps into pots till the ground is workable?
Thanks for advice.
Colta Ives
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Posted by ivesco (from Monterey, MA) on March 23, 2008 at 5:34 PM:
P.S. The foxgloves are going into the woods of SW Massachusetts (Berkshires).
C.Ives
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Posted by critterologist (from Frederick, MD) on March 23, 2008 at 5:59 PM:
Foxglove is pretty hardy... but I'm not sure if those little seedlings would be quite *that* hardy, LOL. I think transplanting into pots (under lights if possible) is a good idea. Foxglove seems to me like something that would look good growing in a clump, so the only reason I can think of to not clump transplant is if they are mixed color seedlings... mixed colors growing in a clump might look pretty cute, but they wouldn't look quite "natural," so I guess it depends on the look you're going for. Even if you clump transplanted and thinned later on, you'd get the benefits of clumped seedlings (moisture management, mutual stimulation for better seedling growth), and it sounds like you'd still have plenty of little foxgloves to plant out.
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Subject: Excellent Article very useful info.
Posted by Baxter_Md (from Chevy Chase, MD) on March 17, 2008 at 11:39 PM:
I have started seeds under lights for the first time. I seem to be having excellent success (took advice from my in-laws and set up the lights close to the hot water tank and furnace for warmth). This leads to my question. I am using a tray with 24 two inch cells and a clear plastic cover. It has only been a little over a week, but many of the seedlings have grown to a size that they are hitting the top of the plastic cover. After germination, is it s good idea to leave the top off?
Thanks.
Baxter
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Posted by critterologist (from Frederick, MD) on March 17, 2008 at 11:47 PM:
Many people do removed the cover at the first sign of germination. Too much humidity can promote damping-off. I keep my humidity dome on a little longer, but I've got a few little holes poked in it for ventilation.
If your seedlings are leggy (tall without having many leaves yet), you might want to move them closer to the lights. Having the top leaves within an inch or two of the bulb will make for nice, sturdy seedlings. Check my other articles on setting up light shelves and preventing damping-off for more details.
Sounds like you got great germination with your setup. Good growing! :-)
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Posted by sesitz (from Fort Worth, TX) on April 15, 2008 at 11:40 AM:
I followed your instructions for setting up a set of lighted shelves. My shelves are composed of wire, so I tied the flourescent fixture to the bottom of one shelf to illuminate the shelf beneath it. I used a chain and "S" hooks to lower or raise the light from the plants. I kept the shelf set in front of a window and used ordinary flourescent fixtures (not full spectrum bulbs). I have successfully grown tomatoes, canterberry bells, wave petunias, impatiens, and datura.
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Posted by critterologist (from Frederick, MD) on April 15, 2008 at 11:55 AM:
Congratulations! It sounds like you're off to a great start for spring planting. I predict that next year, you'll add another light or two... :-)
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Subject: Thanks!!
Posted by rvnsbrk (from Leesburg, VA) on March 13, 2008 at 3:47 PM:
Jill as always you are coming to my rescue at just the right time. Have a bunch of nicotiana and portulaca that I was trying to figure out how to transplant. The clump idea is going to be terrific! So far so good!!
Thanks again,
Juanita
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Posted by critterologist (from Frederick, MD) on March 13, 2008 at 6:30 PM:
I'm glad I could help!
Happy transplanting! Your garden is going to smell wonderful if you've got "a bunch" of nicotiana started... mmmm...
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Posted by KaperC (from No. San Diego Co., CA) on March 13, 2008 at 7:41 PM:
Just in time here, too, Jill! The pictures help a lot, too.
One question: at what point can the little guys be put out in a greenhouse? Ours gets pretty warm, but I open it all up early in the a.m. and we get lots of breezes through there.
Thanks,
Kathleen
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Posted by critterologist (from Frederick, MD) on March 13, 2008 at 7:45 PM:
A lot of the stuff I grow can't take a frost and will pout if night temps are much below 45 or 50 degrees... so I set things out accordingly. I don't have a greenhouse, though, and you're in such a different zone that I hesitate to even try to advise you on timing! You might ask over in the greenhouse forum or in your regional forum. Sorry I can't be more helpful, but I'd rather not give you bad advice by guessing.
:-)
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Posted by KaperC (from No. San Diego Co., CA) on March 13, 2008 at 7:58 PM:
Thanks, Jill. There is a DGer close by who does a lot of propagating - I will check with her.
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Posted by goofybulb (from El Paso, TX) on March 14, 2008 at 1:41 AM:
Great article, as always, Critter!
Pics are really good, suggestive and helpful. Perfectly timed after the friendship basil offer, so we can practice further. You are very clever, the homework that leads to homework, but always exciting and pleasant!!!
I will definitely try your method. Being afraid of clumping, I kept sowing in very small cups, with a few seeds per "cell". It worked for me so far, since I was only trying to get ONE lavender (my nemesis), ONE Stephanotis floribunda, ONE...
but now I have many seeds from somebody very nice and generous (!) and I think I need to expand! I really need a garden though...
I'm looking forward to my "Critter's Pretty Purple Lemon Gemper", I'll send you pics!
Hugs,
Alexandra
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Posted by critterologist (from Frederick, MD) on March 14, 2008 at 2:22 AM:
I'm looking forward to the photos! Happy Sowing!
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Posted by Dea (from Frederick, MD) on March 14, 2008 at 6:23 PM:
Really nice article Jill, the transplanting of seedlings is such a great feeling !!
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Posted by critterologist (from Frederick, MD) on March 14, 2008 at 7:13 PM:
Yes, indeed! It's very satisfying to slide a flat of happy little transplants under the lights... a few days to recover and grow some more roots, and then they take off! :-)
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Subject: Nice Article
Posted by MistyPetals (from North Augusta, SC) on March 13, 2008 at 8:10 AM:
I especially appreciated the tips about getting the nurse leaves under the soil and pulling clumps instead of individual seedlings.
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Posted by pixie62560 (from South China, ME) on March 13, 2008 at 9:48 AM:
Me too, can't tell you how many little seedlings i've lost. Thanks for the great tips and instructions!
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Posted by critterologist (from Frederick, MD) on March 13, 2008 at 11:31 AM:
I know I lost a lot of those delicate little lobelia seedlings when I was potting them up recently... but I sowed seeds heavily and was using pretty thick little clumps, so I know several in each clump will make it despite my handling! That's part of the beauty of this method, I think. (To give you an idea of how thickly I sowed... I had two 6 inch rows of seedlings and filled a 48 cell flat... I'm sure I had about a dozen seedlings in each clump, at least!)
I hope you have good luck using these methods! There are lots of different ways to start seeds, but this is what seems to work well for me. :-)
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Posted by Seandor (from Springfield, MA) on March 13, 2008 at 12:01 PM:
Thanks, critter! This is just the info I need for my 500 plus lobelia! I am very happy - 'cause now I know how to take care of them properly :-) And having lots of lobelia is a good thing, right?
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Posted by critterologist (from Frederick, MD) on March 13, 2008 at 12:04 PM:
Yes! I love having a whole flat of lobelia and another whole flat of alyssum... I get so cheap if I have to pay for them, and I end up buying 2 six-packs when I really want 4... what a great thing to have as many as you could want to tuck here and there in your containers and along your flower borders!
Last year, I put some lobelia in a container that gets shade most of the day, and it kept blooming all summer! Usually, it "melts down" part way through... which is all right as it's often overgrown by other plants in the container by then anyway.
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Posted by Gymgirl (from Houston, TX) on March 13, 2008 at 1:12 PM:
Is this just for certain types of seedlings? If so, what types of seedlings work best with this method? These are the seedlings I started for this spring. Please tell me which would have worked better with this method, than the agonizing one-by-one thing I did....
Marigolds
Zinnias
Sunflowers
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Posted by critterologist (from Frederick, MD) on March 13, 2008 at 1:30 PM:
Anything that naturally grows with a clumping or branching habit will make a nice, full plant sooner with this method. I've used it with Marigolds and been pleased, but I think sunflowers would do better as singles since they make such big stalks. Zinnias -- I guess it depends on the effect you're looking for, whether you want to end up with single plants or clumps, especially if you've got a mix of colors.
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Posted by grampapa (from Wheatfield, NY) on March 14, 2008 at 10:40 PM:
Jill, great stuff! I tend to 'oversow' (big surprise lol). What do you think about snapdragons?
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Posted by critterologist (from Frederick, MD) on March 15, 2008 at 11:31 AM:
I think I haven't had much luck with snapdragons! LOL I don't see any reason not to clump transplant them, though. Just think about the "look" that a mature plant would have if it were a cluster of several plants rather than being a single stem or crown... works for many plants, but might look a little odd for others.
Speaking of crowns, for any seedling that had a distinct crown (leaves radiating out from a point), I wouldn't set it so deeply that the crown is covered by the potting mix -- you want a crown to stay above the soil. Alpine strawberries, for example, I clump transplant but can't really set much deeper than they were growing in their seed starting tray, because I'd cover the crown. You need to have a bit of stem as well as leaves sticking up above the surface of the mix. I hope that makes sense without a photo!
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Posted by Candyce (from The Monadnock Region, NH) on March 16, 2008 at 1:15 PM:
What a great topic!
Thanks for sharing all of your knowledge with us.
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Posted by Peckhaus (from Long Island, NY) on March 17, 2008 at 9:46 AM:
Critter,
Thanks for another great article! Have you ever tried it with lettuce?
Thanks for all your gracious contributions to DG!
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Posted by critterologist (from Frederick, MD) on March 17, 2008 at 9:53 AM:
You're welcome, Peck!
I haven't tried it with lettuce, but I don't see any reason why it wouldn't work. For some reason, I tend to sow tiny pinches of lettuce seed directly into plug trays, and plant the plugs out in the garden. (Between slugs, bunnies, and occasional use of Preen on some beds, I don't generally have much luck direct sowing lettuce or chard, although I have managed to direct sow beets.)
I had an edging of burgundy leaf lettuce along my front landscape bed one year and got a lot of compliments on it. Most people had no idea it was lettuce... :-)
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Posted by Peckhaus (from Long Island, NY) on March 17, 2008 at 10:58 AM:
Thanks! That's a great idea with the burgandy lettuce. Might copy you on that one. Did you begin those seeds indoors as well? I was able to direct sow chard last year, but somebody munched my snap peas to the ground :( This is only my 2nd summer growing veggies, so it's all pretty new. Some of my peppers are emerging! Do you happen to know roughly how long pepper seeds are viable? I noticed those emerging first are the fresher seeds, but it may also be due to the fact that they are different varities than my older seeds...
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Posted by critterologist (from Frederick, MD) on March 17, 2008 at 11:01 AM:
Like tomato seeds, I think pepper seeds are generally good for about 5 years if they're stored at controlled room temp (eg, not in a hot attic)... after that, their germination percentage seems to drop quite a bit. As you noted, it might take a little longer for older seeds to sprout (soaking helps), and germination percentage might be a little lower with older seeds.
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Posted by critterologist (from Frederick, MD) on March 17, 2008 at 11:02 AM:
Oh, and yes I did start the lettuce seeds inside that year... but I've also started plug trays on the back deck for things like that.
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Posted by Peckhaus (from Long Island, NY) on March 17, 2008 at 12:05 PM:
Thanks, Critter!
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Posted by Fitsy (from Hayesville, NC) on March 21, 2008 at 7:24 PM:
Oooops! I didn't know about water drops and
too much moisture! I took the plastic cover off
quick! I see that cupid's dart and carnations and
mace have forgiven me, and are struggling to
sprout anyway.
Thanks for the info! Ain't this fun!
Fitsy
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Posted by critterologist (from Frederick, MD) on March 21, 2008 at 9:54 PM:
Oh, seeds will generally germinate just fine even if your soil is a little wet... but it invites trouble in the form of damping off.
When you're moistening potting mix, scoop up a handful of it... if you can squeeze it into a ball, it's moist enough. If the ball doesn't fall apart easily when you open your hand, the mix is a little wetter than it needs to be. I think I got that tip from Tom DeBaggio, too!
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Posted by Fitsy (from Hayesville, NC) on March 22, 2008 at 7:52 PM:
Thanks! and its misty plastic and planting mix
ball for me from now on!
Fitsy
1
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Posted by critterologist (from Frederick, MD) on March 22, 2008 at 11:55 PM:
As I've said, I think everybody ends up working out a slightly different system that works for them... so if you've got something that works for you, there's probably no need to mess with it... but it can be useful to know exactly what works for somebody else, and that's why my directions were so precise. You may find that something a little different works for you, but this is what works for me.
I sure hope it works well for you, too!
:-)
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Posted by MistyPetals (from North Augusta, SC) on March 29, 2008 at 4:50 PM:
I'm going to be honest and tell you I reread this again today and will probably refer to it several times to glean more from it as I move forward with my seedlings.
This here is a Hall of Famer for beginners.
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Posted by critterologist (from Frederick, MD) on March 29, 2008 at 6:01 PM:
You've set up 
and pots of healthy seedlings!
At the first sign of germination, I make sure my seedling tray is as close as possible to the fluorescent light tube.[2] When seedlings have their first true leaves, and for sure by the time they have their second set of true leaves, they are ready to be transplanted. Looking at the seedling tray from the bottom, you can see vigorous roots searching for more growing room. 
