Water wieght

Ok so I got my scale and here's the results

Dry weight with only bone dry soil in one of those pots is 119g
The weight of each plant is as follows:
WW1: 155 / 36
WW2: 197 / 78
WW3: 177 / 58
WW4: 152 / 33
WW5: 205 / 86
MM1: 196 / 77
MM2: 190 / 71
MM3: 188 / 69
MM4: 180 / 61
MM5: 225 / 106

So as you can tell I really suck at watering by eye, lol.
The measurements are all in grams and the numbers on the right is the approx water in each plant with the dry measurement subtracted from the plant weight.

With the above numbers factored in and assuming that all the plants are now dry, how many grams of water should I be adding per plant?

PS: in-case anyone is wondering, WW = White widow and MM is mix n' match.

Grams of water?

Xephier said:

Ok so I got my scale and here's the results

Dry weight with only bone dry soil in one of those pots is 119g
The weight of each plant is as follows:
WW1: 155 / 36
WW2: 197 / 78
WW3: 177 / 58
WW4: 152 / 33
WW5: 205 / 86
MM1: 196 / 77
MM2: 190 / 71
MM3: 188 / 69
MM4: 180 / 61
MM5: 225 / 106

So as you can tell I really suck at watering by eye, lol.
The measurements are all in grams and the numbers on the right is the approx water in each plant with the dry measurement subtracted from the plant weight.

With the above numbers factored in and assuming that all the plants are now dry, how many grams of water should I be adding per plant?

PS: in-case anyone is wondering, WW = White widow and MM is mix n' match.

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water until you get 10-15% runoff from the bottom of the pots. Over watering is NOT caused by giving too much water when the plants need watering. Rather its caused by watering too frequently.

Alex ^ is right, it's not the amount, it's the frequency of watering

I would think the plants near 150 grams are getting close to needing water, as you wouldn't want to wait until they are 119 ....the others may need to wait a bit more time

so you should be able to feel the weight difference between the plants near 150 grams and the plants over 200....you soon will get the feel for this and will be able to tell just from lifting the plants

For me this would be so much easier if I could just go by the numbers. I've had some random pains in my arms lately(prob due to lack of exercise/healthy eating) and there's times that a cup of water will feel like it weighs as much as a litre. So I don't really trust my judgement when it comes to lifting the plants to test weight. How do I measure % runoff anyways? Sorry if I come off like a moron but this is my first shot at growing anything and I've put a large(for my budget) investment into this and don't wanna mess it up.

When I grow in soil, I use a screen so lifting the pots is not really an option. What I do then is just sick my finger into the soil about 2.5" and if it feels dry all the way down to the tip of my finger, I water.

obvious maybe, but make sure also that the soil that you are watering drain easily. I always like to put a layer of lava rocks in the bottom of the pot before adding dirt. Also add plenty of perlite to air out the mix. I never liked vermiculite because it turns to a globby mess that ends up in the bottom of the pot clogging holes. Good luck

Overwatering is one of the new growers most common mistakes. Overwatering ( meaning frequency ) can smother the roots , by restricting oxygen. The lift the pot method takes time. You can also use a moisture meter , most frown on these but it works. Make sure that your plants can runoff adequately , see how long it takes before it drains. You should see runoff within a minute or two. If your plants are small you can infuse more perlite into your transplant containers if you are upsizing the pots.

Xephier said:

How do I measure % runoff anyways? Sorry if I come off like a moron but this is my first shot at growing anything and I've put a large(for my budget) investment into this and don't wanna mess it up.

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Measure how much water comes out the bottom. Divide by the total you watered with. If you water with 1 gallon and get 1 cup of runoff, you only have 6.25% runoff. (16 cups/1 gallon in, 1 gallon of runoff 1/16 = 6.25% )

Xephier said:

Ok so I got my scale and here's the results

Dry weight with only bone dry soil in one of those pots is 119g
The weight of each plant is as follows:
WW1: 155 / 36
WW2: 197 / 78
WW3: 177 / 58
WW4: 152 / 33
WW5: 205 / 86
MM1: 196 / 77
MM2: 190 / 71
MM3: 188 / 69
MM4: 180 / 61
MM5: 225 / 106

So as you can tell I really suck at watering by eye, lol.
The measurements are all in grams and the numbers on the right is the approx water in each plant with the dry measurement subtracted from the plant weight.

With the above numbers factored in and assuming that all the plants are now dry, how many grams of water should I be adding per plant?

PS: in-case anyone is wondering, WW = White widow and MM is mix n' match.

Click to expand...

Not even sure why this is a concern .
Don't over think things . YOU ARE GROWING A WEED !

dadio161 said:

Not even sure why this is a concern .
Don't over think things . YOU ARE GROWING A WEED !

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In another thread someone told this person to weigh their plants with a scale. (I think they meant it sarcastically.).

To the OP, if you have impaired motor skills a moisture meter may be your best bet. But, you want the containers to feel paper light. You can let them dry until the leaves droop. Then assess the weight of the container (or, what the soil meter says). They'll recover within 30 minutes after watering. You don't want to do this all the time because it is a stress. But, it doesn't hurt to do it occasionally to remind yourself what too dry feels like, and then shoot for getting close to that.

If you're going to err in either direction, err on the side of too dry. Water with enough volume to get 20% runoff. Water in stages over 30 minutes to get the soil saturated before runoff occurs. Be sure to use plenty of perlite in your soil so it drains well and dries quickly. I think it's ideal to water every 2-3 days (if I were in a truly organic, composted soil where I don't supply the nutes with my water, maybe I'd let it dry slower.).

az2000 said:

In another thread someone told this person to weigh their plants with a scale. (I think they meant it sarcastically.).

To the OP, if you have impaired motor skills a moisture meter may be your best bet. But, you want the containers to feel paper light. You can let them dry until the leaves droop. Then assess the weight of the container (or, what the soil meter says). They'll recover within 30 minutes after watering. You don't want to do this all the time because it is a stress. But, it doesn't hurt to do it occasionally to remind yourself what too dry feels like, and then shoot for getting close to that.

If you're going to err in either direction, err on the side of too dry. Water with enough volume to get 20% runoff. Water in stages over 30 minutes to get the soil saturated before runoff occurs. Be sure to use plenty of perlite in your soil so it drains well and dries quickly. I think it's ideal to water every 2-3 days (if I were in a truly organic, composted soil where I don't supply the nutes with my water, maybe I'd let it dry slower.).

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Currently watering daily as per my friend's advice. The plants are just seeds atm so he says they need more moisture for now. I have actually heard that during vegetation it's a good idea to let the plant run completely dry a couple times as it forces the roots to grow out more in search of water.

*Disclaimer* The following advice is NOT for seedlings!


The biggest problem for many new growers, in terms of watering, is that they LOOK at the soil and it looks dry for about the first few inches, so they assume it's watering time and then proceed to water too much. Or, they just go by a set schedule of watering, regardless.

It's a MUCH better idea to weigh the containers when they are drying to give you a sense of how much water is remaining in the soil. It's almost foolproof, in fact!

Various types of soils and mediums will hold water differently so there is no "one" dry weight for all of them. You will have to determine that for yourself by trial.

NEVER go by the number of days to determine when to water because, for one thing, as the plants get bigger, they will drink more water and they will do it faster when they are in very active growth. They will get repotted into larger containers which will negate any previous watering "schedule". As plants near the end of flowering, they will drink much more slowly. The amount of relative humidity in the air will also create different drying times. Going by the weight is a MUCH safer bet. Blindly going by a set schedule of days is about the stupidest thing you could do, really. It just doesn't work that way with plants. Without knowing the size of the containers, the type of medium, the air movement, etc., you can't just assume that every 2-3 days is the way to go.

Moisture meters don't really work that well, either. Don't rely on them.

It's also not ideal to wait until the leaves droop, either. Err on the side of too dry, yes, but don't allow the plants to become desiccated.

Xephier said:

Currently watering daily as per my friend's advice. The plants are just seeds atm so he says they need more moisture for now. I have actually heard that during vegetation it's a good idea to let the plant run completely dry a couple times as it forces the roots to grow out more in search of water.

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if you are watering daily you are likely watering too often, unless in a very hot and/or windy environment

you don't want to let the plant get so dry that it droops, as that's stress but it will recover quickly once watered......on the other hand, it's way worst to over water as that will permanently damage the plant

show us some pics of your plants

Xephier said:

Currently watering daily as per my friend's advice. The plants are just seeds atm so he says they need more moisture for now. I have actually heard that during vegetation it's a good idea to let the plant run completely dry a couple times as it forces the roots to grow out more in search of water.

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I wouldn't let seedlings dry out as much as I wrote in previous post. But, you can definitely overwater seedlings. They can "damp off."

Keep an empty pot filled with dry soil.

Eben on days your arms feel uncomfortable, your plants should almost feel the same as your empty pot.

that way no matter how your arms feel, you can compare your plants to a dry pot.

I ended up mixing up on the methods, water till drops come out the bottom then I weighed them, they all came to 300ish grams each and dry is 119, is 2X the dry weight in water ok for the seeds? Also I just read that compacting the soil too much can be bad for the seeds cuz then they can't get out. the soil is about an inch lower than what it was when I first put it in the pots, is that compacted too much?

Xephier said:

I ended up mixing up on the methods, water till drops come out the bottom then I weighed them, they all came to 300ish grams each and dry is 119, is 2X the dry weight in water ok for the seeds? Also I just read that compacting the soil too much can be bad for the seeds cuz then they can't get out. the soil is about an inch lower than what it was when I first put it in the pots, is that compacted too much?

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Dawg, you are WAY over thinking this. Stop weighing your plants. It will do nothing for you. Just keep the soil moist (not wet) for the seedlings. A solo cup and a turkey baster will make it easier to know what you are doing. In a solo cup, you can give them a drink daily with the baster (2 oz. of water per fill). Go around the outside of the cup with the water to encourage root growth.

Your soil will settle regardless of what is in it. This is totally normal. Just don't "pack" the dirt into the pots when you transplant them. Just relax and let them grow.

Op: the only time I packed a small pot like a bowl, the seedling did die.
That's probably what they mean.
When watering it will naturaly compact over time.