New Grower - Seedling Issues

[Frostage]

Hello all, just joined the forum as I have just started my first grow, but am running into a small issue that I want to fix before it turns into a bigger issue.

I have read the stickies, and here is the required information (with non-relevant lines removed):

What Strain is it? - Dynafem "Big Kush"
Is it Indica, Sativa or Hybrid? What percentages? - 50% indica, 50% sativa
How Many Plants? - 2
Is it in Vegetative or Flowering Stage? - Seedling
Indoor or Outdoor? - Indoor (grow tent)
Soil or Hydro? - 70% Coco coir and 30% perlite
If Soil... What is in your Mix? - As above
If Soil... What Size Pot? - 5 gallon
Size (Wattage) of Light? How Many? 250W HPS with barn reflector
Is it Air Cooled? - Hood/light is not, but tent is cooled with 4" exhaust fan & 3" inlet fan from cool air source
Temperature of Room/Cabinet? - ~26 during light period, ~20 during dark
RH of Room/Cabinet? - Not currently measured, hygrometer in the post
PH of Medium or Reservoir? - ~6 (controlled after adding nutrients)
Any Pests? - None as far as I am aware
How Often are you Watering? - Once every day or two, depending on top inch of medium
Type and Strength of Fertilizers used? - nothing for first week, started adding FloraMicro, FloraGro, FloraBloom, and CalMag in doses according to this guide - i.e. 1/4, 1/8, 1/8, 1tsp respectively per gallon of water
Size or Square Footage of Room? - Grow tent is 50cm wide x 50cm deep x 1m tall

To give a little more information on the grow room; it is a grow tent called "HydroBox Light", which is 50cmx50cmx1m. The light is a 250W HPS bulb with barn reflector (not directly cooled), which is suspended with adjustable ratchet hangers about 60cm from the tops of the seedlings. Cooling and ventilation is done with a 4" carbon filter placed inside the top of the tent, ducted out of the tent to a 4" inline fan, then ducted away. Inlet air is ducted from a cool place into the bottom of the tent, where there is a 3" fan pulling in air. Another 3" fan is on the inside of the tent mounted to the side, blowing air up towards the light to cool it and circulate air.

Now, onto my problem. The seedlings have been growing well (they are now 9 days old) and they have their first set of serrated leaves with the second set well on the way. This morning however I noticed the tips of the leaves were turning slightly yellow.

I noticed that the temperature was rather high, just under 30C (which caused me to add the 3" inlet fan to pull in more cool air), so this is my first suspect.

My other suspect (from reading forums etc) would be overdoing the nutrients. I'm following the guide above exactly, but I'm wondering if I may have started a little early and therefore given them nutrient burn.

My final suspect is the light, which last night I moved closer to the seedlings (~40cm from tops). This obviously contributed to the high heat at plant level, so I moved this back to ~55cm. Could I have light burned the seedlings?

I will get some photos of the setup and plants up later tonight, my phone is playing up at the moment.

Any advice would be greatly appreciated gents, I want to make sure everything goes smooth for my first grow!

 

[dick23rk]

Hey there frostage and welcome to the community! Hoping you can get some pictures up soon so we can get right down to the problem with your plants. From what I have read in your post is that your are going directly by the feed schedule provided with your nutrients. With such a young plant you need to start out with a much weaker strength of nutrients. Always start at 1/4 strength of the recommended dosage and work your way up over multiple feedings. By the sounds of it you may have nutrient burn, but I wouldn't rule out your light being to close just yet. Once you get some pictures up I will try to get back to you with a solution as quick as I can.

 

[Frostage]

Hey there frostage and welcome to the community! Hoping you can get some pictures up soon so we can get right down to the problem with your plants. From what I have read in your post is that your are going directly by the feed schedule provided with your nutrients. With such a young plant you need to start out with a much weaker strength of nutrients. Always start at 1/4 strength of the recommended dosage and work your way up over multiple feedings. By the sounds of it you may have nutrient burn, but I wouldn't rule out your light being to close just yet. Once you get some pictures up I will try to get back to you with a solution as quick as I can.

Thanks for the kind welcome and the advice!

As far as I understand, the nutrient schedule which I'm working to (link in first post) is actually already the correct strength, as suggested by the guys at GWE, it is much less than is recommended on the actual bottles of nutrients.

Perhaps I have misunderstood this!

I am currently uploading photos, they should be up in a few minutes.

Thanks again

 

[Frostage]

PHOTOS!

Grow Tent Setup

This shows my tent setup from the outside, to give an idea of the size.

Grow Tent Setup 2

This shows the tent setup in more detail. You can see the 250W HPS with barn reflector hanging from the top of the tent, then to the right of it is the 4" carbon filter which is ducted out the top to the exhaust fan. To the bottom right is the inlet vent (ducted from cool air source) with the 3" PC fan pulling in air. Finally to the left in the rear corner you can just make out the other PC fan, which is aimed at the HPS bulb to cool it.

Seedling 1 with burnt tips

Seedling 2 with burnt tips

It's not that easy to make out, but you can just about see the yellowing of the tips on the larger leaves.

 

[Vestrimatrik]

My first instinct is nutrient burn, and from what everyone else says, you don't need to add any nutrients for the first couple weeks because the very first little round leaves provide enough to grow for a short period of time. Wait till they yellow up, then start a weak nutrient mix.

I have some seedlings going now and I haven't added anything. They are still growing and are just starting to deplete their tiny leaves.

Use your choice of plain water for a couple days and let us know what happens.

Hope this helps

 

[zacmac]

looks like nute burn. Been there, done that, what works for me is starting out with 1/4 strength no matter what the label says. You can always go up but you cant repair the damage from to much. I like that lil tent too. looks pretty low key.

 

[Frostage]

Thanks a lot for the suggestions guys, it's looking like the consensus is nutrient burn.

This morning I gave a full watering with pure tap water pH'd to ~6. I will continue to do this for the next week or so and see if they start to recover.

My hygrometer arrived last night, and I've noticed that when the light is on the humidity drops to around 35-40% RH (temp ~27.5C). Is this something I should be concerned about? From what I hear the best environment is a little higher humidity in the early stages. If it is too low, what can I do to up the RH? I thought about a saucer of water sat in the tent, which should be evaporated by the light/heat therefore raising humidity, does this sound like a good idea?

 

[Vestrimatrik]

My hygrometer arrived last night, and I've noticed that when the light is on the humidity drops to around 35-40% RH (temp ~27.5C). Is this something I should be concerned about? From what I hear the best environment is a little higher humidity in the early stages. If it is too low, what can I do to up the RH? I thought about a saucer of water sat in the tent, which should be evaporated by the light/heat therefore raising humidity, does this sound like a good idea?

Humidity is a funny thing. Having too low humidity probably won't do anything other than possibly slow growth down. Just the right amount will aid in quick growth, too much and chances for mold go up drastically(trust me, I'm fighting it right now with 70%).

That being said... I've tried the saucer "trick" and you only gat about 5% increase. I have heard of people hanging a towel or washcloth in there so the air circulation wicks away the moisture. The only problem I find with that is having to wet the towel every day.

What you could do is get yourself a hand towel to hang just above a pure water container with the end of the towel in contact with said water. The water will travel up the towel and be taken away by any air circulation.
You might also be able to adjust the amount of humidity simply by controlling how much surface area of the towel is outside the water being used.

Keep in mind, as the towel is moist for long periods of time and mold loves moisture, you should probably consider washing or changing the towel every week or so.

 

[Frostage]

Some very interesting suggestions there!

I like the idea of a small towel hanging with the bottom in a bowl of water. It would seem to me that this would also serve to lower the overall temperature in the tent because of the evaporation, which may allow me to move the light slightly closer without risking the higher temps (I can only get it to ~45-50cm from the tops of the plants at the moment before the temp rises to ~29-30C, though I might be able to get it closer now I've improved my ventilation with the inlet fan).

I'm quite interested in the subject of growing (obviously otherwise I wouldn't be doing it!). I'm a bit of a perfectionist and I do enjoy talking about scientific reasons and solutions, so I want to learn as many lessons as possible as early as possible!

 

[Vestrimatrik]

Some very interesting suggestions there!

I like the idea of a small towel hanging with the bottom in a bowl of water. It would seem to me that this would also serve to lower the overall temperature in the tent because of the evaporation, which may allow me to move the light slightly closer without risking the higher temps (I can only get it to ~45-50cm from the tops of the plants at the moment before the temp rises to ~29-30C, though I might be able to get it closer now I've improved my ventilation with the inlet fan).

I'm quite interested in the subject of growing (obviously otherwise I wouldn't be doing it!). I'm a bit of a perfectionist and I do enjoy talking about scientific reasons and solutions, so I want to learn as many lessons as possible as early as possible!

is the right place to start. So many growers here with so much experience that can and ARE willing to help.

Im a bit of a perfectionist myself so I know what your talking about.
Research and learn from your mistakes, I made my fair share on my first grow but that's before I knew about the 420 community and what they had to offer!

You should go check out the grow journals forums and start one(if you haven't already), I'd love to see how they turn out.

 

[TheGanjaMon]

Great post. Will keep an eye out on your grow as I started my own recently too. Good job so far!

Sent from my SM-G925W8 using 420 Magazine Mobile App

 

[dick23rk]

Well frostage, looks like you got everything under control here now. I wasn't on here early enough to catch all the conversation, was getting things done in the garden for my journal update today. You seem to have gotten the help you need for now, lots of good information from people on this site. Another thing to remember is to water until you get some run off, especially once they start getting fed nutrients. This will wash out any unused nutrients and salt build up which will reduce later issues. Coco and perlite is very easy to flush as well if you end up feeding to strong of a mix any time in the future so this is a good thing! Keep up the good work and enjoy your time here at 420 Mag!

 

[Frostage]

Thanks for all the responses, much appreciated.

I do intend to start a grow journal at some point, I have plenty of photos right from seed but unfortunately not a lot of time to put everything together at the moment!

dick23rk - No worries, I've been well looked after! As you say, plenty of good information from some very experienced guys.

I haven't actually been watering with runoff, only enough to moisten the soil when the top starts to look dry (if you look at the seedling 2 picture above, I'd probably water shortly after that as there are dry spots appearing). Do you think I should switch to watering less often (I've heard some people say when the top inch of soil is dry), and with some runoff?

Took a look at your grow journal by the way, looking very nice! Also very exciting to see where I'll be in a few weeks time!

 

[dick23rk]

I would say keep watering how you are til about 2 weeks old. When you start feeding nutrients be sure to get at least 10% run off but without making the coco super saturated. This will help wash out the old and bring in the new without nute build up or lockouts.