Help with new cannabis seedlings in solocups?

[jokerlola]

I germinated and planted 7 cannabis seeds in solo cups a couple of days ago and today they have all popped up above the soil. I have the solo cups in a homemade humidity dome (an upside down plastic tote) and I have that in a south facing window that gets direct sunlight most of the day. These plants will be grown outside in 5 gallon Smart Pots.

Now that they've all popped up, should I still keep them in the humidity dome? And if so, for how long? Also, what is the best way to water them? How do I know when and how much?

I've been growing outside in Smart Pots for 4 years but from clones. Last year I tried seeds for the first time and had a lot of trouble with damp off and/or seedlings dying of not enough water from trying to avoid damp off. Is there a fool proof way of watering seedlings in solo cups to avoid these problems.

 

[Melville Hobbes]

Best to get the dome off of them when they're above the surface, don't want them damping off.
@Brewsterman has made his own device to water seedlings, maybe he'll post a pic here too. There are a lot of people starting seeds right now, and this subject has come up.

 

[Joe Brewster]

Best to get the dome off of them when they're above the surface, don't want them damping off.
@Brewsterman has made his own device to water seedlings, maybe he'll post a pic here too. There are a lot of people starting seeds right now, and this subject has come up.

Thanks Melville for the tag Yes get the dome off if the humidity diff is large remove it slowly by opening a corner first allowing it to adjust watch for wilting ( clones mostly )
water near the out side of cup to get the roots searching for water try to keep the stem dry
as the plant gets bigger you can give it more water each time let it dry in between watering

Here is a link to a post I started in DIY Precision Seedling Watering Bottle

 

[CrimsonEcho]

pull the dome off their stems will rot otherwise

 

[Azimuth]

Now that they've all popped up, should I still keep them in the humidity dome? And if so, for how long?

No, I agree with the others. While clones benefit from a dome for the first few days as they get established, seedlings don't need a dome. In fact, as you have stated a dome creates other problems.

However, it your plant is now used to the humid atmosphere of the dome, you might need to harden it off by gradually exposing it to ambient air.

Open the dome slots if it has them, or you could tilt the dome to allow fresh air in, gradually, over a period of a few days increasing the opening.

Or, just remove the dome for a few minutes a couple of times a day gradually increasing the amount of time.

If you see wilting that means it's not ready yet and should be immediately re-domed.

Also, what is the best way to water them? How do I know when and how much?

Here's a good thread on watering.

Last year I tried seeds for the first time and had a lot of trouble with damp off and/or seedlings dying of not enough water from trying to avoid damp off. Is there a fool proof way of watering seedlings in solo cups to avoid these problems.

I've had great success using worm castings to counteract damping off disease.

That is a fungus which rots the stem right at ground level and mostly in overly moist conditions.

A gentle breeze over the seedlings will go a long way in preventing this issue.

But the microbes in worm castings deal with it quite effectively. I soak the seed in a weak worm casting tea for 24 hours and then plant the seed in my mix and dribble the same soak water on the top of the mix where the seed went. Haven't had any issues since using this combination.

 

[jokerlola]

No, I agree with the others. While clones benefit from a dome for the first few days as they get established, seedlings don't need a dome. In fact, as you have stated a dome creates other problems.

However, it your plant is now used to the humid atmosphere of the dome, you might need to harden it off by gradually exposing it to ambient air.

Open the dome slots if it has them, or you could tilt the dome to allow fresh air in, gradually, over a period of a few days increasing the opening.

Or, just remove the dome for a few minutes a couple of times a day gradually increasing the amount of time.

If you see wilting that means it's not ready yet and should be immediately re-domed.


Here's a good thread on watering.


I've had great success using worm castings to counteract damping off disease.

That is a fungus which rots the stem right at ground level and mostly in overly moist conditions.

A gentle breeze over the seedlings will go a long way in preventing this issue.

But the microbes in worm castings deal with it quite effectively. I soak the seed in a weak worm casting tea for 24 hours and then plant the seed in my mix and dribble the same soak water on the top of the mix where the seed went. Haven't had any issues since using this combination.

I soaked the seeds for 36 hours in cups of water and was going to germinate them in paper towels but they had already cracked open and produced tap roots. So I planted them in soil in solo cups Thursday evening and put them in my DIY humidity dome and they all had already popped up above the soil by this afternoon (some this morning). So they've only been under the humidity dome (after popping up) for about 12 to 15 hours. So I should take them right out of the dome or gradually over the next couple of days? I am in Denver Colorado so the ambient humidity is pretty low.

 

[Azimuth]

Take off the dome, but watch for drooping. Shouldn't have an issue with that short of a time but your ambient conditions could affect them.

If they droop, just use the hardening off process.

And I soak my seeds generally for 24 hours like you did. Most of them will pop open and get planted. The ones that don't go into paper towels inside a plastic bag.

 

[jokerlola]

Thanks Melville for the tag Yes get the dome off if the humidity diff is large remove it slowly by opening a corner first allowing it to adjust watch for wilting ( clones mostly )
water near the out side of cup to get the roots searching for water try to keep the stem dry
as the plant gets bigger you can give it more water each time let it dry in between watering

Here is a link to a post I started in DIY Precision Seedling Watering Bottle

What is the best way to know if they need water?

 

[Joe Brewster]

What is the best way to know if they need water?

The soil should be visibly dry on top , use your finger 1-2" down & get to know the feel of your container when dry . You can fill a similar container with dry media for compassion
water when it feels lite but don't let it dry so much that it is drooping
As it gets bigger about 4- 5 leaves you can water to the point that you get a bit of water coming out the bottom
Always give time to dry before watering Don't water every day
It is best to water when lights come on or soon after
looks like you are in something like promix ? Looks damp enough now

 

[Azimuth]

This is the toughest stage to water properly since the seedling doesn't have enough roots to start the wet/dry cycle. Like Brewster says, your mix looks OK now. I like to bottom water at this stage since it will provide some moisture down low for when the roots get to the bottom of the cup which they probably are already.

I stand the cup in another slightly wider container with maybe 1/2" of water in it. You don't want to soak the medium but rather just provide a little something for the roots to find when they get down there.

Leave that setup just long enough for the soil at the bottom of the cup to soak up a small amount of moisture and then take it out. Once you get the first set of true leaves you'll be on your way.

Also, it's hard to tell from your pictures, but those cups need drainage holes or slits in them at the very bottom and bottom sides.

 

[jokerlola]

This is the toughest stage to water properly since the seedling doesn't have enough roots to start the wet/dry cycle. Like Brewster says, your mix looks OK now. I like to bottom water at this stage since it will provide some moisture down low for when the roots get to the bottom of the cup which they probably are already.

I stand the cup in another slightly wider container with maybe 1/2" of water in it. You don't want to soak the medium but rather just provide a little something for the roots to find when they get down there.

Leave that setup just long enough for the soil at the bottom of the cup to soak up a small amount of moisture and then take it out. Once you get the first set of true leaves you'll be on your way.

Also, it's hard to tell from your pictures, but those cups need drainage holes or slits in them at the very bottom and bottom sides.

Yes, I do have drainage holes at the bottom of the Solo cups.

When I put the cups in a tray with 1/2" of water, should I let them soak up all that water or just some of it? Is it best practice to water this way until they get their first true leaves?

 

[Azimuth]

I'd only leave it in until the bottom 1/2" was wet then take it out. It's really more to provide a prize for the roots for reaching the bottom rather than a good watering. After they get their first couple of sets of true leaves you can start the wet/dry cycle and thoroughly wet the soil.

Just not yet. You basically just want to provide enough moisture to see the seedling through the next few days. And you shouldn't need to do this more than a couple of times before you get those true leaves and can start watering normally.

Others suggest dribbling water near the seedling to get its roots to follow the water down. That's too complicated for me and this way works just as well to my eyes, and so much simpler.

 

[skirk]

When I used solo cups I would get the dry weight and wet weight. As you can see the difference is a bit over 60 grams or two ounces of water. I would add water when i got within 10 grams of dry weight and keep it 5 grams below wet weight.

 

[jokerlola]

I'd only leave it in until the bottom 1/2" was wet then take it out. It's really more to provide a prize for the roots for reaching the bottom rather than a good watering. After they get their first couple of sets of true leaves you can start the wet/dry cycle and thoroughly wet the soil.

Just not yet. You basically just want to provide enough moisture to see the seedling through the next few days. And you shouldn't need to do this more than a couple of times before you get those true leaves and can start watering normally.

Others suggest dribbling water near the seedling to get its roots to follow the water down. That's too complicated for me and this way works just as well to my eyes, and so much simpler.

Thanks so much. Yeah, water from the bottom seems to be the simplest and should keep me out of trouble.

 

[jokerlola]

When I used solo cups I would get the dry weight and wet weight. As you can see the difference is a bit over 60 grams or two ounces of water. I would add water when i got within 10 grams of dry weight and keep it 5 grams below wet weight.

I forgot about using this weighing method. That was one of the things I did last year when I was finally successful with a couple of seedlings. Thanks.

 

[TorturedSoul]

While clones benefit from a dome for the first few days as they get established, seedlings don't need a dome. In fact, as you have stated a dome creates other problems.

I don't even like using them to root cuttings. I've had too many wilted cuttings (especially if I've tossed a few extras, wrapped in damp paper towels, into the refrigerator to deal with later, or... thought I miscounted by one until the next morning when I discovered an escapee between the couch and end table ) stand at attention within an hour of sticking them into some kind of media (or a glass of water) to think I actually need one. I suppose it's very much a "YMMV" kind of thing, and people who have dessert humidity or high heat - and some people do - might find that their unrooted clones are transpiring moisture at a greater rate than they are able to uptake it. But, for me, simply ensuring a good (fresh) angled cut on the end has always been sufficient.

 

[Azimuth]

When I used solo cups I would get the dry weight and wet weight. As you can see the difference is a bit over 60 grams or two ounces of water. I would add water when i got within 10 grams of dry weight and keep it 5 grams below wet weight.

That's good too. I use that method after the seedlings get a bit more established. Before they have their true leaves you really shouldn't put all that much water in the cups or you could drown them. Or at least stunt them early.

 

[Azimuth]

I don't even like using them to root cuttings. I've had too many wilted cuttings (especially if I've tossed a few extras, wrapped in damp paper towels, into the refrigerator to deal with later, or... thought I miscounted by one until the next morning when I discovered an escapee between the couch and end table ) stand at attention within an hour of sticking them into some kind of media (or a glass of water) to think I actually need one. I suppose it's very much a "YMMV" kind of thing, and people who have dessert humidity or high heat - and some people do - might find that their unrooted clones are transpiring moisture at a greater rate than they are able to uptake it. But, for me, simply ensuring a good (fresh) angled cut on the end has always been sufficient.

That depends a lot on your conditions (ambient temperature and humidity). I have better success using a heat pad and covering them for the first few days. Some methods, like water based ones, have enough humidity that they don't need them at all. Methods like your glass of water, or the water based cloners.

 

[TorturedSoul]

dessert humidity

Oops .

Some methods, like water based ones, have enough humidity that they don't need them at all. Methods like your glass of water, or the water based cloners.

I use a glass of water when I'm not in a hurry. Learned it from Mom (who learned it from her mother), who has been using the method for ~70 years. Not with cannabis, but it's one of those "a plant is a plant" situations. She rarely even bothers to change the water.

"Fancy" version - bucket, using a $1 Styrofoam(?) circular float from the craft store with some holes in it, and an aquarium air pump/stones setup seems to work a little faster, and is what I'd use if I was doing >dozen at a time, probably.

When working with Mom's houseplants, where I'm not greatly concerned (just cut another one if it fails), I sometimes just cut, recut under running water when ready to use, make a hole in some kind of pot full of media, stick, and lightly tamp down to ensure soil-to-stem contact, and tell her to water it far more frequently than the established plants (which she tortures to the point of a Geneva Accords violation, lol) she has. Most of those are fine, too.

Most (meaning the vast, overwhelming majority) of every method I and her have used to root cuttings have worked. I used to pass out lots of ones that I did by mixing 1/3 soil, 1/3 perlite, and 1/3 vermiculite (simple reason: had equal amounts of each ), stuck a cutting into a transparent water bottle, and waited until there were roots showing all around the bottle. Not exactly a way that I'd recommend, due to "<YELL!!!> LIGHT REACHING ROOTS!" but it worked. The plant world survived for 500,000,000 years, almost entirely without our help(?), and through more than one Level 5 Extinction Event. Unsurprisingly, they seem to survive being left alone to get on with it.

Er... Apologies for the digression from main subject of thread.

 

[jokerlola]

Oops .



I use a glass of water when I'm not in a hurry. Learned it from Mom (who learned it from her mother), who has been using the method for ~70 years. Not with cannabis, but it's one of those "a plant is a plant" situations. She rarely even bothers to change the water.

"Fancy" version - bucket, using a $1 Styrofoam(?) circular float from the craft store with some holes in it, and an aquarium air pump/stones setup seems to work a little faster, and is what I'd use if I was doing >dozen at a time, probably.

When working with Mom's houseplants, where I'm not greatly concerned (just cut another one if it fails), I sometimes just cut, recut under running water when ready to use, make a hole in some kind of pot full of media, stick, and lightly tamp down to ensure soil-to-stem contact, and tell her to water it far more frequently than the established plants (which she tortures to the point of a Geneva Accords violation, lol) she has. Most of those are fine, too.

Most (meaning the vast, overwhelming majority) of every method I and her have used to root cuttings have worked. I used to pass out lots of ones that I did by mixing 1/3 soil, 1/3 perlite, and 1/3 vermiculite (simple reason: had equal amounts of each ), stuck a cutting in, and waited until there were roots showing all around the bottle. Not exactly a way that I'd recommend, due to "<YELL!!!> LIGHT REACHING ROOTS!" but it worked. The plant world survived for 500,000,000 years, almost entirely without our help(?), and through more than one Level 5 Extinction Event. Unsurprisingly, they seem to survive being left alone to get on with it.

Er... Apologies for the digression from main subject of thread.

That's the one thing I've never been successful with is rooting a cannabis cutting in just plain water. I have no problems using peat pods or rock wool cubes or soil but I have always needed some kind of humidity dome or plastic bags to hold in the humidity, maybe because I'm in Colorado and it's so dry. But If I try to root in the open, they quickly wilt and die.

As far as rooting in plain water, I've had cannabis cuttings live for weeks and weeks out in the open but never develop roots. But I've rooted plenty of other things in plain water like basil, snake plants, tomato plant cuttings. pothos. But for some reason not cannabis. The few times I did finally get some roots in water, the roots were so fragile that the cutting didn't survive the transfer to soil.