Seedlings look hungry for N but EC of run off says different

[SweetSkunk]

Hi all,

Getting towards the end of week 2 growing in Coco.

• Gave the 1L (1 quart) starting pots a pre water with feed 0.5ml/L A+B,EC 0.6 (100ml feed; 1/10th of the pot volume)
• Planted seeds.
• 4 days later, gave another feed of same nutrients but 200ml (2/10ths the pot volume)
• 1 day into week 2, I gave a water with just pH adjusted water (pH 6-6.1, EC 0.4) till run off, 400ml. EC run off was the same as the initial two feeds, 0.6-0.7 EC
• I've just given them another water (4 days since last water with just pH adjusted water) and the run off is reading the a bit higher 0.8 EC.

With the above information, does this sound like the beginning of salt build up?

I am noticing my plants looking hungry for N with a lighter green on the first set of leaves.

I had also noticed that after the first time I had watered with just pH adjusted water, the plants dropped for a couple of days. I assumed this was just the hefty water they had had and was perhaps over water slightly. Now i'm inclined to think that salt build up is happening with the above observations, looking hungry, EC of run off higher than feed and the drooping is perhaps "under watering" as the salt is preventing them drinking?

Any thoughts?
Many thanks
Ss

 

[Mañ'O'Green]

Well you could very well have a salt build up because you are not fertigating properly. Coco is hydro not soil. You need to fertigate to 15 to 20% run-off every day. Do not let the plant sit in the run-off it needs to be removed. Fertigate the entire pot.

Oh yeah, what is the red tube? does that have a slit to allow expansion because if not you will girdle that plant and reduce its vigor substantially.

 

[SweetSkunk]

Well you could very well have a salt build up because you are not fertigating properly. Coco is hydro not soil. You need to fertigate to 15 to 20% run-off every day. Do not let the plant sit in the run-off it needs to be removed. Fertigate the entire pot.

Oh yeah, what is the red tube? does that have a slit to allow expansion because if not you will girdle that plant and reduce its vigor substantially.

Thanks for your reply mate!

So this is something I have been unsure of. From the reading I've done, it's still not clear how much water to give them a seedlings/ from the beginning. If I was to water the pot till run of whilst the seeds have just a tap root, would they not drown?
I've read to treat the plant like soil whilst they are young.

If then also read to wait till the pot is starting to dry on top before watering again, which certainley isn't everyday at their current size.
I'm all ears as to what your opinions are in this!

Furthering to that, would you recommend watering till run off again tomorrow, (done today) even with the size of the plants?
Run off is always removed.

The red tube is a straw with a slit in it. Is removed later.

Cheers!
SS

 

[Mañ'O'Green]

Thanks for your reply mate!

So this is something I have been unsure of. From the reading I've done, it's still not clear how much water to give them a seedlings/ from the beginning. If I was to water the pot till run of whilst the seeds have just a tap root, would they not drown?
I've read to treat the plant like soil whilst they are young.

If then also read to wait till the pot is starting to dry on top before watering again, which certainly isn't everyday at their current size.
I'm all ears as to what your opinions are in this!

Furthering to that, would you recommend watering till run off again tomorrow, (done today) even with the size of the plants?
Run off is always removed.

The red tube is a straw with a slit in it. Is removed later.

Cheers!
SS

A tap root can grow 9 inches in 3 days. The idea behind coco as a substrate is you cannot over-water it. It is true that when a plant is a seedling - the first few days. You do not want the surface of the coco to remain too wet this will promote "damping off". If you have good air circulation in the space this is unlikely as the surface will dry reasonably fast. As the water easily drains from coco it pulls air into the pot for the roots. Your roots will not drown. Soil does not behave like this as water stays tight to clay. Air is much slower to get to the roots and must be given time to dry down some. Coco has no nutrients to speak of on its own so the plant needs to be fed from day one. 1/4 strength for germination and the first week. Then 50% strength for the next week then add 10% each week until you see a little bit of tip burn. Then back off 10%.

What you need to learn about watering will come with practice. Here are the basic rules: Never let the soil dry out. Soil and or coco can become hydrophobic if allowed to dry. This means it repels water. This in turn will create dry pockets in the soil and roots there will die. If your soil - coco have accidentally dried out use a surfactant to help re-wet it. I like yucca powder. Don't let soil remain soggy by watering too much too often. Root rot, damping off, molds, fungus gnats and other problems start in soggy soil. When you do water water the entire pot. How to learn when to water starts before you plant the seed. Fill your container with fresh soil/coco and weigh it (heft it) this is the lightest weight and consider it a dry pot. Now slowly water until the soil/coco will no longer absorb the water and run-off begins; weigh the pot (heft it) this is the maximum water, the wettest the pot can get. The difference between wettest and driest is the maximum water weight, for ease of explanation lets just say the water weighs 20 pounds. When the pot loses 10 pounds (half of the water weight) it is time to water again. There is an art to watering. Now with coco that will be sufficient but growers wanting to push the envelope can fertigate many times a day to really attempt to push the plant by having fresh in balance nutrients in the root zone all day. The watering window (time frame) is from 2 hours after lights on to 2 hours before lights out.

I don't think the straw is a good idea. It will foster too much moisture and open the plant to attack from molds and rot. That stem needs air flow to remain healthy. If the stem is too long lower your lights and be sure the fan is stirring the air gently. The small movement of the plant strengthens it.

 

[SweetSkunk]

A tap root can grow 9 inches in 3 days. The idea behind coco as a substrate is you cannot over-water it. It is true that when a plant is a seedling - the first few days. You do not want the surface of the coco to remain too wet this will promote "damping off". If you have good air circulation in the space this is unlikely as the surface will dry reasonably fast. As the water easily drains from coco it pulls air into the pot for the roots. Your roots will not drown. Soil does not behave like this as water stays tight to clay. Air is much slower to get to the roots and must be given time to dry down some. Coco has no nutrients to speak of on its own so the plant needs to be fed from day one. 1/4 strength for germination and the first week. Then 50% strength for the next week then add 10% each week until you see a little bit of tip burn. Then back off 10%.

What you need to learn about watering will come with practice. Here are the basic rules: Never let the soil dry out. Soil and or coco can become hydrophobic if allowed to dry. This means it repels water. This in turn will create dry pockets in the soil and roots there will die. If your soil - coco have accidentally dried out use a surfactant to help re-wet it. I like yucca powder. Don't let soil remain soggy by watering too much too often. Root rot, damping off, molds, fungus gnats and other problems start in soggy soil. When you do water water the entire pot. How to learn when to water starts before you plant the seed. Fill your container with fresh soil/coco and weigh it (heft it) this is the lightest weight and consider it a dry pot. Now slowly water until the soil/coco will no longer absorb the water and run-off begins; weigh the pot (heft it) this is the maximum water, the wettest the pot can get. The difference between wettest and driest is the maximum water weight, for ease of explanation lets just say the water weighs 20 pounds. When the pot loses 10 pounds (half of the water weight) it is time to water again. There is an art to watering. Now with coco that will be sufficient but growers wanting to push the envelope can fertigate many times a day to really attempt to push the plant by having fresh in balance nutrients in the root zone all day. The watering window (time frame) is from 2 hours after lights on to 2 hours before lights out.

I don't think the straw is a good idea. It will foster too much moisture and open the plant to attack from molds and rot. That stem needs air flow to remain healthy. If the stem is too long lower your lights and be sure the fan is stirring the air gently. The small movement of the plant strengthens it.

Mate I really appreciate your advice!
So to clarify, your advice would be to pre water till run off before planting and then to water as required once the pot weight is approx half of a saturated pot.

How important is it to water at the specific time you have proposed? I can always get into my space everyday but getting in at set times isn't always easy due to work.

The straws where used as I had a bit of stretching and lowering the lights caused a spike in temps
Straws are removed now and temps good.

One more question for your in relation to watering, when I pot up to my 10L pots, would you also give these a water till run off. I think it will take a considerable amount of time for the pots to lose enough weight to be ready for another water/feed.

Again thanks for you're help and advice!

 

[Mañ'O'Green]

Mate I really appreciate your advice!
So to clarify, your advice would be to pre water till run off before planting and then to water as required once the pot weight is approx half of a saturated pot.

How important is it to water at the specific time you have proposed? I can always get into my space everyday but getting in at set times isn't always easy due to work.

The straws where used as I had a bit of stretching and lowering the lights caused a spike in temps
Straws are removed now and temps good.

One more question for your in relation to watering, when I pot up to my 10L pots, would you also give these a water till run off. I think it will take a considerable amount of time for the pots to lose enough weight to be ready for another water/feed.

Again thanks for you're help and advice!

Yes, The minimum fertigation in coco is at 50% water remaining in the pot. You can fertigate more often if you wish just do not let the pot dry out.

You do not want to water before the lights have been on for 2 hours because during the night the roots have been exuding substances that encourage the microbes to produce elements the plant needs. If you water before the plant has a chance to absorb them it is a waste and the plant gets less of what it needs. Fertigating washes these away from the roots.

I cannot remember the scientific reasons for not watering after 2 hours prior to lights out - there are some. I just remember an old farmer telling me plants do not like to go to bed with wet feet .

With coco you do not have to wait for 50% water wight - it does not matter. With soil it is important.