Seed starting mix

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karstopography
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Re: Seed starting mix

#21

Post: # 89419Unread post karstopography
Sun Feb 19, 2023 8:00 am

I never cover the seed starting cells with plastic or plastic domes or humidity tents. The Baccto premium soil is moist to begin with, I might add a little water to the potting soil before placing the seeds if the soil isn’t quite moist enough. I press the thin layer of jiffy starting mix onto the top of baccto potting soil and that will generally moisten the jiffy mix enough. The seeds get placed and gently pressed into that now barely moist jiffy mix, then a top layer of jiffy is added to cover the seed and that too gets pressed into the seed starting cell. I’ve also prewetted the jiffy mix and then squeezed most all the water out. I want the jiffy to be barely moist at any rate and definitely not sopping wet.

I’ll use a misting sprayer if the top layer of jiffy starting mix appears to be a little too dry or completely drying out. I won’t do anything but mist the top layer periodically as needed until the seeds are well sprouted and growing. Seems like I won’t need to water until the true leaves are showing. When I then water I water thoroughly and let it soak in from the bottom for a bit, then drain the pan completely and let everything air out in some place with moving air.

A little diluted fish emulsion might get added to the water in the late stages, although the Baccto premium feeds the seedlings enough for the most part.

But, I can’t see the need for plastic covering or domes to hold in moisture. Seems like it’s asking for trouble or dampening off.
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JayneR13
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Re: Seed starting mix

#22

Post: # 89427Unread post JayneR13
Sun Feb 19, 2023 8:55 am

Cranraspberry wrote: Sat Feb 18, 2023 10:12 am @JayneR13 thank you! I’ve actually read lots of good about the MG mix, but isn’t it also a peat and perlite combo like Espoma? Jiffy had vermiculite and peat, which caused even more issues. I also tried a “fancy” Organic Mechanics peat-free mix last year and it was the worst of the bunch - pine fines, rice hulls and coco coir were the base.

<snip>
Yes, it's a mixture of sphagnum moss, perlite, fertilizer, and a wetting agent they don't specify. It's not designed to grow plants long-term but it does help them develop a nice root system. As I've said, I've used it for years with good results. The Espoma might have been a bad batch but given the problems I had, never again in my garden! I'm sticking with what works well for me. As for you, are you sure it isn't user error that's causing the problems? Perhaps you're over-watering? That's an easy thing to do, especially since peat moss holds water and never really dries out once it's soaked. Or watering unevenly, so the plants don't get enough water? I've done that recently, growing dwarf tomatoes in this mix. My Tiny Tim is doing well in it, whereas my Dancing with Smurfs doesn't seem happy at all. Have you considered making your own mix?

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Cranraspberry
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Re: Seed starting mix

#23

Post: # 89431Unread post Cranraspberry
Sun Feb 19, 2023 9:25 am

@JayneR13 oh I am certain it’s user error! But since I can’t quite seem to dial in on the watering, maybe I need a more forgiving mix.
I have found that things do better once I raise the lights and put a fan on, although certain cells just seem to struggle. Just potted up my chives since they kept getting moldy in the little 1x1” cells, and need to do the same with my thyme.
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Cranraspberry
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Re: Seed starting mix

#24

Post: # 89434Unread post Cranraspberry
Sun Feb 19, 2023 9:33 am

@karstopography I do tend to keep mine covered with plastic wrap before the seeds germinate, but interestingly enough I have so far (knock on wood) had no issues at that stage. All my problems arise after the plastic is gone. It doesn’t appear to be damping off - I’ve seen that with our direct sowed seedlings outside, it’s more like the seeds germinate, the cotyledons start unfurling and then the whole thing just stalls and eventually dries out. The stem is fully intact and the seedling is upright, but the roots never progress. I just lost 3 out of 4 cells of chard which prompted me to try something different this time.

If anyone wants to play seedling autopsy, here’s a baby cabbage that didn’t make it.
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GoDawgs
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Re: Seed starting mix

#25

Post: # 89435Unread post GoDawgs
Sun Feb 19, 2023 9:41 am

To each their own....whatever works! :D

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Re: Seed starting mix

#26

Post: # 89442Unread post Seven Bends
Sun Feb 19, 2023 10:36 am

Cranraspberry wrote: Sun Feb 19, 2023 9:33 am It doesn’t appear to be damping off - I’ve seen that with our direct sowed seedlings outside, it’s more like the seeds germinate, the cotyledons start unfurling and then the whole thing just stalls and eventually dries out. The stem is fully intact and the seedling is upright, but the roots never progress. I just lost 3 out of 4 cells of chard which prompted me to try something different this time.
From your posts about your seedling troubles, I'd say your problem is 95% likely to be overwatering (possibly in combination with room conditions or something you're adding to your soil, but focus on the watering first). Your photos show seedlings that didn't grow any normal, deep roots, just some surface roots. That's a diagnostic sign of overwatering.

My advice: stop bottom-watering. It can work fine, but it's not working for you at this point, so try a different approach.

Water from the top. Water infrequently and not very much. If your growing conditions are cool and your mix is peaty, you may only have to water once a week or even less when the seedlings are tiny. And each cell may only need a teaspoon or two of water when the seedlings are tiny. Before you water, test whether they NEED water, not by looking at the top of the soil, but by picking up the pot or pack to feel how light it is.

Try to water your little seedlings in a way that doesn't pack down the mix. You can make yourself a mini sprinkling can with a water bottle, or hold your fingers over the mouth of the water bottle so just a little water dribbles out, or pour some water into your hand and let it dribble off your fingers. Avoid dumping a flow of water into the pots/cells when the seedlings are little.

Different cells/pots will need different amounts of water. If you have some cells that are dry and crusty, and others that are green and moldy, don't give the green and moldy cells any more water until that problem is solved. For green/moldy cells, your best bet probably would be to repot them right away, in fresh, drier mix.

For your next seed starting attempt, use a new bag of prepackaged seed starting mix and don't add anything else to it. Moisten the mix in a bowl or basin until it is moist/crumbly, not soggy. Fill your cells/pots with the mix and don't pack it down -- tamp it very gently or bang the containers on the counter to remove air pockets, but don't pack it down.

Plant your seeds, don't water any more, and cover the containers with plastic wrap. Put them on a heating mat if you have one, or in a warm place. As soon as the first seedlings sprout, remove/turn off the heating mat and remove the plastic wrap. Resist your urge to water.

Maybe as a test, plant an extra pot of seedlings, let the seeds sprout, and then don't water that pot at all until the seedlings exhibit some drought stress. That will give you an idea how long it takes for the mix to dry out, and how light the pot feels at that point. (You don't want to drought-stress the rest of your seedlings, though -- that's a ticket to edema).

Another good way to learn how much to water is to plant some seedlings in a clear container, so you can see the soil moisture/texture and the progress of the roots.

If you're growing your seedlings in a cold or damp basement, that could be contributing to your problem. Move them upstairs somewhere (at least some of them, as a test).

Don't fertilize your seedlings when they're still small; it's easy to stunt or kill them then. Don't add anything like Epsom salts or lime to your seedling mix; don't water with anything except plain water when the seedlings are small.

I think with all the information available on the internet, it's easy to overthink and over-complicate this. Keep it simple, don't overwater, and you'll have good results.

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Re: Seed starting mix

#27

Post: # 89448Unread post Cranraspberry
Sun Feb 19, 2023 11:04 am

@Seven Bends thank you so much for trying to help me troubleshoot! Full disclosure: the bottom watering this year is an attempt to fix things, because I was top watering my fall seedlings and that did even worse 😂. But top watering at the early stages seems like the best solution here. I’m using the Burpee seed cells with silicone bottoms which are fairly see through, so you think it would make it idiot-proof, and yet here I am.

That being said things aren’t hopeless, I just feel like they could be better, and the chard loss (3 out of 4) was definitely the worst out of anything I’ve experienced so far!
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brownrexx
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Re: Seed starting mix

#28

Post: # 89455Unread post brownrexx
Sun Feb 19, 2023 11:55 am

@Cranraspberry I totally agree with the advice given by @Seven Bends I think that you may have drowned your little cabbage seedling.

I am not in favor of seed starting trays like the one pictured above because the bottom is enclosed and it will tend to keep things overly moist and even soggy.

I have a very small seed starting set up and I use cells that can be cut apart if the plants have different watering preferences. I do not always water every cell in the tray, just the ones that are dry. As you can see they cells sit on an open tray so that the cells can drain completely and they never sit in standing water.

All of that being said, I think that your seedlings look really nice. I would just get them out of that deep tray and they can have more air flow.

As I was looking through pictures to attach to this thread, I found one that shows the Espoma potting mix that I used 2 years ago and you can also see how I have separate little cells that can be cut apart if necessary. I do use a plastic dome over the tray until the seeds start to germinate and then I remove the cover to avoid excess moisture.


ImageLettuce & Bok Choy by Brownrexx, on Flickr


Image20200315_155518 by Brownrexx, on Flickr

JayneR13
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Re: Seed starting mix

#29

Post: # 89457Unread post JayneR13
Sun Feb 19, 2023 12:14 pm

FWIW I agree with @brownrexx on the trays. I also use larger 3"x3" plastic pots and water them very carefully, especially once the potting mix becomes saturated. I give just a little water a few times per day while the roots are tiny. Then when true leaves develop, I give a bit more only less times per day, and only when the pot is light. It's like feeding a baby, if that makes sense. Babies eat small meals several times per day. When they're older, they eat larger meals but only a few times per day. Plants are like this too. Bigger pots will also help root development, and the roots have room to grow in. Those small pots are like too tight shoes. Bigger pots and refining your watering schedule will help, I think. And be sure to either put up a small desk fan or shake your seedlings every day, so they develop good stems. A gentle breeze does wonders. And you do know about hardening them out before transplanting, right?

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Re: Seed starting mix

#30

Post: # 89469Unread post Seven Bends
Sun Feb 19, 2023 1:43 pm

brownrexx wrote: Sun Feb 19, 2023 11:55 am
Image20200315_155518 by Brownrexx, on Flickr
@Cranraspberry -- It's hard to beat the 1020 trays and inserts (shown in @brownrexx's photo) for starting and growing your own seedlings. These are what growers have been using to produce "market packs" for ages.

I believe what's shown in the picture is a 606 insert (6 packs, 6 cells per pack). I mostly use 804 inserts (8 packs, 4 cells per pack), which have the same size cells as the 606 inserts, just grouped differently. I use 804 4-packs for cabbage, broccoli, eggplant, peppers and tomatoes. The brassicas I plant directly from the market packs to the ground without potting up. Eggplant and peppers sometimes get potted up once, not always. Tomatoes usually get potted up once into 4" pots or big plastic cups. I use 806 and 1206 inserts for lettuce & flowers.

You can see the different sizes and arrangements here: https://www.greenhousemegastore.com/pro ... 1884118215. I found 1020 trays and several sizes of inserts this week at Merrifield Garden Center, sold individually ($1.99 per insert sheet, can't remember the 1020 tray price). You can use the inserts without the 1020 trays if you put something like styrofoam trays under them to catch drainage. The benefit of the 1020 trays is that they're sized to fit and make it easy to carry things around.

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Re: Seed starting mix

#31

Post: # 89480Unread post brownrexx
Sun Feb 19, 2023 3:35 pm

Once my tomato and pepper seedlings get bigger they get "potted up" into larger pots but I use the same trays. I pot them in potting soil at this point, not seed starting mix.

Last year I discovered a really easy way to put them out during the day and bring them in at night. I use my John Deere Gator. I back it out onto the driveway during the day and drive into the garage for the night when it is too cold for them to stay outside. Eventually I drive the trays to the garden and plant the plants.


Image20220503_164650 by Brownrexx, on Flickr

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Re: Seed starting mix

#32

Post: # 89484Unread post Cranraspberry
Sun Feb 19, 2023 3:50 pm

@JayneR13 I have some of the deep 3.5” pots (they are 3.5” square, but 5” tall, so a good amount of volume) from Greenhouse Megastore that I was planning to use for potting up peppers and tomatoes. It’s a long story, but I had purchased those pots and the corresponding liners and then had to get separate pricey Garland trays because the dimensions are a hair too big for the standard 1020 trays. For some reason I got very confused with all the smaller flat options they offered and just gave up. Not sure I’m going to pot the cabbages up though, it’s been so warm here that the cabbages might be ready to go out into the garden fairly soon, so I might take a chance on leaving them in the small cells (they are 2x2x2”).
I do have some spinach and arugula starts hardening off as we speak! I’m probably a little more cavalier with the cold winter plants (tatsoi and komatsuna went in after 3 days) than I should be, but I’ll be more careful with nightshades. We’re in a city condo, so hardening off is a logistical challenge and I’m always nervous to leave things unattended for long.

@Seven Bends those look great. I’ve also seen youtubers use similar cells, but made out of sturdier than average plastic (I believe they are sold branded under Charles Dowding and Epic Gardening and probably something else), but I suspect that if I buy anything else this season my husband will serve me with divorce papers. Grow lights and rack were my big battle for this year, not going to push my luck further ha.
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Re: Seed starting mix

#33

Post: # 89529Unread post svalli
Mon Feb 20, 2023 8:43 am

I have used moler clay granules, which is a type of diatomaceous earth, for many years to start my tomatoes, but this year I am wondering, if I should buy a new bag of it or try something else. I ordered rock wool cubes to be used in my indoor gardening systems and same time ordered some peat based cubes too. I have now sown micro tomatoes to those cubes and germination was quick and roots looked nice. I have now sown pepper and dahlia seeds to those and I am waiting for germination.

Rosy Finch in Root Riot.jpg



I do not have enough of these cubes for all of the tomatoes, and now I am contemplating if I could use the rock wool for starting tomatoes, even those will be planted to peat based mixture later.

Sowing in moler has the advantage, that I can put multiple seeds in one cell, because transplanting the ones, which have germinated is easy. That is good specially for the older seeds, which have lower germination rate.

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JayneR13
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Re: Seed starting mix

#34

Post: # 89539Unread post JayneR13
Mon Feb 20, 2023 11:10 am

@svalli I don't see any reason you couldn't start seedlings in rock wool. It's done for hydroponics, as you may well know. Have you tried Jiffy pellets?

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Re: Seed starting mix

#35

Post: # 89548Unread post svalli
Mon Feb 20, 2023 2:50 pm

JayneR13 wrote: Mon Feb 20, 2023 11:10 am @svalli I don't see any reason you couldn't start seedlings in rock wool. It's done for hydroponics, as you may well know. Have you tried Jiffy pellets?
I have two hydroponic indoor gardens and I purchased the rock wool cubes for them, but I have so many that I could use some for seed starting.
I have used jiffy pellets and my first peppers this year I started in them. Real Jiffy pellets are quite expensive here, but work better than some of the cheap copies.
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Re: Seed starting mix

#36

Post: # 89557Unread post pepperhead212
Mon Feb 20, 2023 4:42 pm

I use Jiffy Pellets for things that I don't grow long before transplanting - mostly squash, cucumbers, melons, and okra. But last season I planted some eggplants in some, only because the usual trays with pots were almost filled, but a lot of space in the one tray of JPs, so I planted a dozen in those, on 3-27, and on 4-23 all of them had roots on the outside, so I transplanted all of them to the larger pots - 18/tray, space available once my cold weather crops were outside - and in just a week they were huge! I've never had eggplants grow this quickly! Tomatoes and peppers did ok in JPs when I tried them, years ago, but nothing like this. I will use them for eggplants again this season, and see if the same happens.

My usual seed starting mix is whatever I get a buy on, plus some extra perlite and peat, plus a little worm castings. I sterilize a good amount of it in my oven, @ 200°f, and once cool, mix some myco, plus some Bt israelensis into it, for the fungus gnats. Pepper seeds I start in shallow strip trays of vermiculite, transferring the rooted seeds to the pots.
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Re: Seed starting mix

#37

Post: # 89603Unread post rossomendblot
Tue Feb 21, 2023 6:11 am

Cranraspberry wrote: Sun Feb 19, 2023 3:50 pm @Seven Bends those look great. I’ve also seen youtubers use similar cells, but made out of sturdier than average plastic (I believe they are sold branded under Charles Dowding and Epic Gardening and probably something else), but I suspect that if I buy anything else this season my husband will serve me with divorce papers. Grow lights and rack were my big battle for this year, not going to push my luck further ha.
The Charles Dowding ones are manufactured by a UK company called ContainerWise - https://containerwise.co.uk/

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Re: Seed starting mix

#38

Post: # 89658Unread post Cranraspberry
Tue Feb 21, 2023 1:42 pm

@rossomendblot after taking a closer look I noticed that they were different, but I think they are made out of a similar heavy duty plastic to the Bootstrap Farmer/Epic Gardening ones.
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JayneR13
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Re: Seed starting mix

#39

Post: # 89659Unread post JayneR13
Tue Feb 21, 2023 2:11 pm

pepperhead212 wrote: Mon Feb 20, 2023 4:42 pm <snip>

My usual seed starting mix is whatever I get a buy on, plus some extra perlite and peat, plus a little worm castings. I sterilize a good amount of it in my oven, @ 200°f, and once cool, mix some myco, plus some Bt israelensis into it, for the fungus gnats. Pepper seeds I start in shallow strip trays of vermiculite, transferring the rooted seeds to the pots.
Do you have good luck with oven sterilization? I've tried it for my mushroom mycelia and it's molded every tine. 300F for 3 hours too. Ugh.

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Re: Seed starting mix

#40

Post: # 89663Unread post pepperhead212
Tue Feb 21, 2023 2:38 pm

@JayneR13 I have never had a problem after that sterilization, as far as damping off, or anything else that fungus or bacteria might cause. That's strange that you have problems after using an even higher temp, for longer.
Woodbury, NJ zone 7a/7b

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