When to Pot-Up?

Lexington, KY(Zone 6b)

How do you know when to pot-up vegetable seedlings?

SE Houston (Hobby), TX(Zone 9a)

Tomato seedlings are usually potted up after they get their second set of TRUE leaves. The very first leaves you see are the cotyledons, or 'NURSE' leaves, from which the plant draws its initial nourishment. They'll eventually shrivel up and drop off. You are looking for two complete sets of leaves to come out past the nurse leaves. Then, away we go!

What did you start your seedlings in? What type of container/pot? And, are they under enough light to keep them from growing thin and straggly trying to reach some light? Plain old fluorescent shop lights from HD run approx. $10 for a two light set. I have two sets on each of my shelves, for a total of FOUR lights per shelf. Seedlings need adequate light!

I just started a 2nd batch of tomato seeds on February 14th, in 6 oz. yogurt cups. They're already showing the first true leaves, and by next weekend, I'll be potting them up to drinking water bottles, where they'll grow on until April 3rd. Then, they'll go outside for one week of acclimation to the outdoors (called "Hardening off"), and planting on April 10th.

I'm allowing 8 weeks from sowing to planting. Since it's getting warmer, they can speed the process up by one week, depending on how fast they grow, and how it is outside...


P.S. Water your seedlings from the top with a Turkey baster for about the 1st four waterings. Add 1 cap of Hydrogen Peroxide to a gallon of tepid water for your watering. After the 4th watering, start watering from the bottom of the trays only. Let em soak up what they want for about 10-15 minutes, then drain the excess out with the Turkey baster. Never let your seedlings soak in the water...


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Lexington, KY(Zone 6b)

Thanks for all the wonderful info. I wish I had your set-up, but unfortunately, I don't have the room to do all that, or a husband handy enough. I purchased a seedstarting set from Gardener's Supply. It has a mat that soaks up water from the bottom tray-seems to be working fine. All I've started so far are lettuces, brocolli, kale, spinach and rosemary. Its too early to start my tomatoes & peppers, which is KILLING me! Everything else I'm doing is direct-seeded, and I can't do that till mid-March. Back to my set-up, right now my lights are propped up on stacks of books. I have one grow light which my husband purchased and one regular desk lamp. I am going to get a shop light this weekend-which is what I asked him to get to begin with-and hopefully get him to hang it. I'm thinking now that I may not even have to pot-up the lettuces, etc. They're going into patio containers, so after hardening off, I may just go on & plant them in the pots. Do you think that would be okay? Then I can plant my tomatoes and peppers and go from there. Maybe by that time he'll have hung the light!-with any luck at all!

SE Houston (Hobby), TX(Zone 9a)

I did my shelf set-up all by myself. Are you smarter than a 5th grader? Then, you can do it too! The only tool you need is a handdrill with a tiny bit to start a pilot hole (a "starter" hole), so that when you HAND screw in the eyebolts, you don't split the wood. This would be an excellent project for you to learn how to drill holes, if you don't already know how!

The setup is just concrete blocks from HD ($1.50/ea.),with 1x12 boards sitting on top. The great part about the setup is you can have the boards cut to the length you have space for, long as it's at least 5-1/2 long (so the 48" shop lights have room). They'll cut them for you before you leave the store! How cool is that?? 4 blocks and 1 board cut in half will get you two shelves. Put two shop lights on each shelf for a total of 4 lights per shelf.

That's it!

P.S. I have that same APS Deep Root System from Gardener's Supply. I have the 15-cell setup. IT IS WONDERFUL!!! Use it for your peppers, which take a bit longer to germinate. The dome will help with the heat they like.

Start your tomato seeds off in 6 oz. yogurt cups with holes drilled in the bottoms. Then plant them up to 4" pots or drinking water bottles after the 2nd set of true leaves. The depth of the water bottles will help the tomatoes develop a good root system.

So, while you're waiting on the weather, start collecting yogurt cups from your friends, and drink a case of bottled water (24 bottles?). NOTE: Some water bottles have straighter sides than the Ozarka bottles. Some have a deep-curve section where you hold them. Look for the straightest sided water bottles. Makes it easier to get the root ball out of the bottle, without having to cut it open. Otherwise, you'll have to cut the bottle...


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Lexington, KY(Zone 6b)

The other problem is that the room I'm using for the plants is also home to my cat's litter box. I moved her box a couple of weeks ago in order to set my seedlings in front of the window. She freaked out!! Quit using the box altogether-so you know who won that battle! So my seedlings are on top of a microwave stand next to the window. We're going to hang the shop light over that. Best I can do right now. Thanks for the advice about the tomato seedlings. I had already started saving yogurt cups-guess I had seen some of your other postings! I'm just bored right now with nothing to plant.

SE Houston (Hobby), TX(Zone 9a)

There's no boredom in the garden! Start collecting the water bottles and poking holes in the bottoms. I heat up an old Philips screwdriver on the stove burner and burn five holes in the bottoms of the bottles. After you've got holes, cut the tops off. Then, grab a black Sharpie marker and start labeling all your containers with the name, date you sowed the seed, and the DTM date (e.g., 75 DTM, 54 DTM) so you'll know when to expect your harvest after you plant out.

That should keep you occupied for a minute!

Hugs! ^^_^^

Albuquerque, NM(Zone 7a)

By the way... not to toot my own horn or anything, but... OKAY, I'll admit it, I'd like to pause here for a moment to toot my own horn.

I see a lot of people mentioning yogurt cups as good starter containers. This became an especially popular idea several years ago, after Joey Green mentioned it in some of his "all the things you can do with Dannon yogurt" writings.

But do you know who gave Joey Green the idea in the first place?

I don't really mind that Joey never gave me credit. I wasn't expecting anything in return, and I'm not surprised I didn't get it.

As for one brand over another, well, the Dannon cups are still mostly the nice semi-rigid kind of plastic that creates your drainage slits in the bottom with a nail or sharp pencil + one light tap with a hammer. Making drainage holes in the soft plastic that, for example, Mountain High uses, takes a bit more work. Dannon used to sell yogurt in EIGHT ounce cups, which were nicer for gardeners for obvious reasons, but I'm pretty sure those days are gone forever.

SE Houston (Hobby), TX(Zone 9a)

Well, who knew I'd sit in the face of pure genius. THANK YOU, THANK YOU, THANK YOU!

And, you're right. The days of the 8oz. yogurt cups are gone forever!

I use the HEB brand cups, cause that's what I buy. I have about a gazillion of them, and find that it's making more sense on several levels to use and reuse these. I now have others saving their cups for me.

At least they won't end up in the landfill -- at least for awhile!


P.S. Keep those gardening ideas coming, ok? ^^_^^

Clover, SC

You are wise to wait to start your tomato plants until 6-8 weeks before you set them out in the garden ... tomatoes love heat. They struggle when set out too early in the garden. Hang in there. Spring is coming! http://www.tomatodirt.com/seed-starting-timetable.html

Lexington, KY(Zone 6b)

I guess I'm just such a novice. ..most all my seedlings have more than 2 leaves on them. Right now I'm growing several types of lettuces and brocolli (sp?-I'll never learn how to spell that veggie!). I don't know how to tell what the "true leaves" are. I planted 3-4 seeds in each cell and they ALL came up & ALL have several leaves on them. Should I just clip some of them down? They're too tiny to separate as well as too close together.

SE Houston (Hobby), TX(Zone 9a)

We were ALL such novices, in the beginning. That's the beauty of belonging to Dave's Garden. There are other, more experience growers here with TONS of information and YEARS of experience, and they're all willing to share the knowledge!

Ok. Did you reread my post above about how to identify the "true" leaves. Locate the very first two leaves you saw when the seedling came up. Those are NOT true leaves. They are the cotyledons, or nurse leaves. Look for at least 4-6 leaves that have come up after those first two. If you can count at least 4 new leaves, POT UP THE SEEDLING.

Now, regarding more than one seedling in the same pot. You have two options:

1. Simply snip out the stems of all but the STRONGEST looking seedling in that pot. You will still need to pot it up when it gets at least the 4 TRUE leaves... or,

2. Let all of them grow together, until the majority get 4 TRUE leaves, then, separate the seedlings. You can do it. That's how I managed to end up with 208 tomato seedlings last January -- I can't ever bear to just destroy a perfectly good seedling, no matter how many there are...

If you attempt to separate multiples in a pot, here's how I do it:

FIRST AND FOREMOST -- Avoid handling the seedling by the stem, as much as you can avoid doing so!!! You can damage it without knowing it. Handle the seedling by the leaves, to the extent you can do so....

►Withhold watering so the soil dries out just a little bit, but not totally, just before you start separating. If you water beforehand, the soil will stick together too much, and you'll have a harder time teasing the root balls apart.
►Since you're using the APS deep rooting system, your root balls should already be nicely developed, which puts you ahead with each seedling in the cell.
►There's a BIG HOLE in the bottom of each cell, right? That's the beauty of this system. The hole is so you can stick a finger in and push the entire plug out from the bottom! Do it.
►Once the plug is out, use a kitchen fork to gently tease the plug into sections/chunks with a seedling in each chunk. You might manage to get it right in half, you might not -- no matter, long as you work gently, and don't handle that stem more than you have to. Try to keep as much soil as you can on each root ball.
►Now, depending on what you're potting the plant into, drop a little potting mix into the bottom of your vessel. You don't need very much in the bottom, because the seedling will develop roots along all of the stem that is buried, so the more stem buried, the more roots developing. Try to expose only the leaves above the 2 nurse leaves, if you can. Plant the seedling deep.
►So, drop that seedling down as far down as you can (which is why I'm liking those drinking water bottles more and more for potting up...see the link below for a picture)
►Hold the seedling in the middle of the vessel with one hand and drop more potting mix down into the vessel with your other hand. Once the seedling is anchored about halfway with mix, you can stick your fingers in and gently press down the potting mix. Very gently. If you can't get your fingers in, just give the bottle a firm tap on the counter so the mix settles down. However, you don't want to PACK it down too tight....Keep filling the bottle, leaving about 1" before the rim. If you have to top water for a minute, you need this space to avoid your mix washing out.
►Once you have all your vessels potted up, set them into a drip tray and use your kitchen hose sprayer to GENTLY water in from the top, JUST until you see water coming out of the bottoms of the bottles (DON'T FORGET TO POKE DRAIN HOLES IN THE BOTTOM). Don't over-saturate. They'll suck up any remaining water as they need too. If you have more than about 2" of water that's dripped into the tray from all the bottles, suck it out with a turkey baster after about 10-15 minutes. This is excess water the plants have not sucked up.
►Never let your seedlings sit in the excess water, after they've been in it for a maximum of 15 minutes. By then, they've taken up what they want.
►All future watering should be from the bottom of the tray.
►When I water seedlings for about the first 4-5 waterings, I add 1 capful of Hydrogen Peroxide to one gallon of WARM water and pour it into the tray until it rises about 1-1/2" inches up the bottom of the bottles. The peroxide helps with damping off (in my experience). Damping off is that seedling malady that causes your seedling stem to turn black, pinch itself closed, and kill your seedling. It is believed that watering seedlings from the top contributes to damping off. Not sure why it happens, but it can. Since I've used the H2O2, I've not had an instance of damping off.
►If you notice your leaves turning purple, this is an indication your babies are too cold, and too wet at the same time. You know how a human baby turns blue when it's too cold? Same thing...So, adjust your watering and/or your room temperature. Check for DRAFTS!!! They are notorious for causing "blue baby" syndrome...
►Warm in the beginning is great for germination. However, after your babies have popped, it's best to turn down the heat, and grow them on in a cooler temperature. Too hot, and they'll grow long, leggy, and straggly. You want them to grow short, fat, and stocky. The cool will facilitate this, so adjust accordingly.
►Finally, not enough light will cause long, leggy and straggly seedling, as they stretch to find the nearest light source. I use two regular 48" fluorescent shop lights per shelf (side by side) for a total of 4 lights per shelf. Concrete blocks and wood board shelves...

►I'm generally potting up with used potting mix that I've sterilized in the microwave, so my potting mix is WARM to the touch when I pot up.
►I use WARM to the touch water from the tap when I'm watering the seedlings in.

I've learned that WARM is a recurring theme with tomato seedlings....

LMK how you make out, ok?



P.S. Go look at this thread. She's the fellow gardener I learned about the water bottles from...


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Lexington, KY(Zone 6b)

Thank you SO much, Linda! I will print this out and put the instructions near my "babies"! I guess I'm too anxious. I DID read your first post about the 1st two leaves, it's just that most of mine have four-all close together-kind of like clover. I noticed you were originally talking about tomatoes, so I wondered if lettuce & brocolli were different.
Also thanks to Kathy for the link! I'm just so impatient! I'm ready for Spring and gardening outside again!

Lexington, KY(Zone 6b)

BTW-my babies aren't blue-they're very healthy looking and LOVE their new shop light!They have a very cold room to grow in, the cat's happy and life is good!
P.S. I see your point about the water bottles. They'll make nice deep "pots" won't they?

SE Houston (Hobby), TX(Zone 9a)

Cold Human babies = blue
Cold tomato/seedling babies = Purple ^^_^^

If you go with the water bottles, buy/collect the brand with the straightest sides you can. Ozarka water bottles have a mean "waistline" and you HAVE to cut the bottle open to release the plant. Some of the straighter sided bottles will allow you to push from the bottom and the plant will slip out easier -- so you can reuse your bottles!

Albuquerque, NM(Zone 7a)

There's also a third alternative for two seedlings in the same cell: just plant them both together, even when you're transplanting into the open ground. Less transplant shock-- which can set some vegetables back by as much as a week or more if it's severe enough-- and the two plants will ultimately produce more foliage or fruit than one plant would in the same spot. Less harvest, however, than if they were separated with little or no transplant shock, and planted farther apart. (Or at least that's what some say who have more experience with this technique than I do; I've only tried it once or twice, not a proper scientific test.)

There's also a possibility that if one of the pair comes down with an especially debilitating disease, such as Early Blight maybe, you can remove it before the disease has spread to the other plant, and thus use your garden space more efficiently.

Vitamin B1 solution is available in concentrated form at most garden stores, and is quite inexpensive. Best solution to possible transplant shock is to add a little of the concentrate to the water you're using to "water in" your transplants. Works like a charm, even if you're as clumsy as I sometimes am in separating seedlings.

Lexington, KY(Zone 6b)

Thank you petronius for those last tips. I took today off from work to do all this, and I'm nervous about it, but I imagine the plants will do just fine. I'm going to quit fretting, just do it and let the chips fall where they may. If it doesn't work out, I've learned a lot, and there's always more seed!! Happy Spring!!

Charlotte, NC(Zone 7b)

I was going to say: "Never handle a seedling by it's stem," but I see Gymgirl already covered that.

SE Houston (Hobby), TX(Zone 9a)

I LEARNED that from you!!! LOL!!! ^^_^^

Lexington, KY(Zone 6b)

Well, all my different lettuces, kale and spinach are separated and planted in water bottles, yogurt cups, whatever I could find. Now I see why you said to save lots of them Linda! I potted mine up to patio containers, but am giving lots away to others. Question-looks like I should keep them in a shaded area for awhile to help them deal with transplant shock-is that correct??

SE Houston (Hobby), TX(Zone 9a)

Yes, Peggy!

Use the drinking water bottles for the giveaways! Actually, you end up putting more potting mix in those water bottles vs. a yogurt cup, but if you want a good-sized giveaway, with a nicely developed root system, and you don't mind spending the $ on the potting mix, go for it.

Otherwise, make your hobby pay for itself, and charge enough per plant/flat to at least cover your potting mix expense. Most people are more than willing to make a donation when you explain that you'll need to buy more potting mix, for NEXT time...

Just remember to collect bottles with the straightest side walls you can find. Easier to remove without that "girlie waistline" on the bottle!


Fort Worth, TX(Zone 8a)

This year, I used single-serve applesauce cups to start my seeds in. They worked great!

Lexington, KY(Zone 6b)

We don't eat applesauce @ our house!! Maybe we should start, lol!

SE Houston (Hobby), TX(Zone 9a)

The fruit and pudding cups are made of the same stuff!

Fort Worth, TX(Zone 8a)

I like them because they're small and you can write on them with a sharpie. I usually buy applesauce in the big glass jar because it's more economical, but because I wanted to use the cups for seed starting, I sacrificed and bought the single-serve 6-pack.

Lexington, KY(Zone 6b)

The things we do in the interest of gardening! I guess I'll just have to eat more pudding-that will work!! Thanks again!

Laingsburg, MI

Thank you, Gymgirl, for your wonderfully detailed explanation of potting up with tomatoes. Would this process also apply to other vegetables? What about lettuces?

I started all of my seeds in the Jiffy peat thingies that expand when watered. Do I remove the white netting before transplanting?

I realize that I waited too long before ordering tomato seeds. I planted them last week and have yet to sprout. (I changed to a flourescent light yesterday from an OTT light.) Could I replant them in the garden outdoors, say, after a month or so of growth indoors? How can I tell when they're ready to be hardened off and transplanted? Should I just chuck this season's tomatoes from seed and try again next year?

Thank you again for your willingness to help!

Laingsburg, MI

Forgot one question. Can you explain this APS Deep Root System?

Charlotte, NC(Zone 7b)

HopeSue - tomato seedlings should be ready to harden off 4 to 6 weeks after they sprout. They will be ready to set out in the garden about two to four weeks after your last expected spring frost.

SE Houston (Hobby), TX(Zone 9a)

The APS is a fine system of deep cells that allow your seedling to stay in longer and fill out the cell. You end up with a larger, deeper root system on the seedling without having to pot up.

I'd use it for cabbage, broccoli, and cauliflower seedlings that don't need to be potted up before you harden them off for the garden. The more developed these brassica seedlings are when you harden and transplant, the better chance your crop will have.

Charlotte, NC(Zone 7b)

Gymgirl - how deep are the cells in your APS system? I would like to compare the dimensions to the 3oz plastic Solo cups I've been using. The dimensions of the 3oz cups are two and a quarter inches deep. The top is two inches across tapering to a one and a half inch base.

I very rarely have to pot-up using these cups and I've been reusing them for at least nine years.

The soil mix I use is very porous, so I'm able to keep a very shallow layer of water in the trays so the seedling never get thirsty.

SE Houston (Hobby), TX(Zone 9a)

I believe my APS Deep Rooting System is 3.5" deep, tapering down to 2.5"? It's a pretty big cell, but perfect for rooting the brassicas. They take so long to grow, I can start 'em, and leave 'em alone and comfortable, til it's time to harden off. And the larger a brassica seedling is at transplanting, the better the chance of good plant development during the rest of the cool/cold season.

They don't sell the APS 15-cell system anymore. Only the refill dome and drip tray. I bought two before they discontinued this model, and glad I did. 30 is just about perfect for me!

CORRECTION: They DO still sell the 15-cell system!

Charlotte, NC(Zone 7b)

Gymgirl - thanks for checking the dimensions for me. That's a nice size for starting seedlings.

As to rooting brassicas - I prepare the bed for them, then sprinkle the seeds at one end. As the seedlings emerge and get to a nice size, I dig them up, (taking as much of the attached soil as possible) and carefully place them in a hole already prepared for them.

To prepare the hole, I dig down at least 6" and about as wide. I fill the hole with water and let it drain. If it drains real fast, I fill with water again. I fill a third time if it still drains fast. I then add fertilizer - brassicas are heavy feeders - then mix it well with the surrounding soil. Once each starts to grow, I place mulch around the base, but not touching the stalk.

I place each transplant slightly deeper than it grew originally.

I have found growing broccoli a good two feet apart gives them the space they need. The ones I grew last winter had heads that were eleven inches across. The stumps on those things were like tree trunks, and didn't break down in the compost. I had to run the mower over them this spring when I mulched the leaves!

Incidentally, I don't "heal-in" any plant. I've seen this demonstrated many times on TV gardening shows and it drives me crazy! Plants like air around their roots. Healing-in presses the air out! If there's an air-pocket down there, the rain will wash the soil into it in no time. I don't even "press firmly" around transplants for the same reason. I've also seen them twist plants into the soil! Goodness knows what that does to the roots!

I'll stop ranting now ^_^

SE Houston (Hobby), TX(Zone 9a)

That RANTING makes me wanna cancel the two additional 15-cell trays I just ordered...

ONLY because I have almost an entire 4x8' raised bed that only has 8 tomato plants growing at one end! The entire rest of the bed is covered by a thick layer of 6-mil plastic to keep the cats out...

It would make perfect sense for me to do just what you said you do. I can use the deep cell trays to start annuals/perennials/something ELSE!

PLEASE, keep on ranting!


SE Houston (Hobby), TX(Zone 9a)

What do you prepare your bed with for the brassicas? I've had success adding Black Kow composted manure in the past, and I know just how hungry those hippos can get!

Charlotte, NC(Zone 7b)

Gymgirl -

What do you prepare your bed with for the brassicas?

During the fall and spring I remove worm castings that earthworms have created from all the leaves added to the walkways, plus about an inch or so of compost. If the bed has shrunk somewhat, I'll also add coir.

Our backyard is a sea of brown leaves!

Everett, WA(Zone 8a)

One nice thing about cells in trays is that they don't tip over! And I've re-used those 72-cell "6-packs" at least three years. They only get brittle if I leave them out in the summe rsun (UV, I assume).

If you can't find yogurt cups, Dixie cups or Solo cups can be bought in almost any size. I find I can use one for 2-3 years before tjhey get brittle. I two of them crack, next year just nest them together so the cracks are on opposite sides and keep using them.

For p;otting up and seedling-untangling, I like a long-pronged cocktail fork I got from Goodwill for about 15 cents. It had three prongs, so I bent the middle one back a little. The increased spacing and "fore-and'aft" prongs just seem handier, somehow. And when I'm carrying a seedling from one tray to the pot in another tray, the cupping effect keeps it from falling off.

Like like plastic mustard or ketchup bottles for top-watering seedlings. You can find them with small openings, so that just a few drops at a time come out when you shake a mustard bottle. Ketyhcup bottles are better folr a steady stream.

I'm too clumsy to use a turkey batser folr watering - I use it for removing water from a tray.

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