Seedlings - calmag, curling leaves, grow medium

I have two marijuana plants that I started from seed. I currently have each plant in a small plastic cup and they are still in the seedling stage. I am attaching a photo of them (with some tomato seedlings)

Yesterday I put the plants in my grow tent. I have CFL bulbs combined with LED bulbs for a total wattage of 1,300 equivalent.

As you can see, one of the plants still has its initial leaves and has not grown anymore. The other plan has a second set of leaves that were growing nicely until I put them in the tent.

I had my lights about 13 or 14 inches from the canopy. After one day of being in the grow tent with those lights, the plant with the additional leaves started to curl at the leaf tips. I raised my lights 6 inches.
I should add that yesterday I gave each plan a dose of Cal mag. The strength was one teaspoon to 1 gallon of water. I am using distilled water.

I plan on putting the plants in Coco coir when they are ready.

Does anybody have any suggestions as to why the leaves are curling and what I should do about it? Does anybody have any suggestions as to whether I should reset my grow tent and if so how? Any comments on the lights? Should I be using calmag on either seedling while still in soil?

Please help.I provide you with the following additional information to help you make suggestions and formulated diagnosis:

What strain, Seed bank, or bag seed: feminized seed from seed bank - strain unknown

Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF - potting soil then coco coir

Vessels: Pots, Grow beds, Buckets, Troths -
plastic cups then fabric pots

PH of Water, Solution, runoff (if Applicable) -
water has PH of about 6.

PPM/TDS or EC of nutrient solution if applicable -

Indoor or Outdoor -

Light system -
cfl (600 watts EQ) led (700 watts EQ)

Temps; Day, Night:
72 degrees Fahrenheit

Humidity; Day, Night -
50 to 60

Ventilation system;
negative pressure for intake; desk fan for exhaust

AC, Humidifier, De-humidifier, Co2 -

Thanks for your help.

Edit: I removed personal contact info, please make sure not to post emails, phone numbers, etc.

im no pro so youll have to wait for others, but do wanna point out that when you are figuring your light wattage, you dont go by equivalent, you go by the actual wattage used from wall

i will also say, when i had leaves curling like that, it was a ph issue

One other thing don’t no if you have them in it or no but should put the clear cups in something so the roots can grow more I made something out of cardboard just form it into a circle around the cup and good to go that’s just me happy growing :v:.

I have a question, do your cups have drain holes in the bottom? They look wet to me, but could be the way my phone shows. I would make sure you have drainage, and put clear cups into a red cup. Roots and light not good combo. Clear cups are typically used so grower can observe the root growth and determine transplant.

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So if I understand they looked ok till they went into the tent then the leaves curled.
You raised the light…which was the right thing to do…so whats next?
The leaves damaged by heat or intense light will not get better. So watch for new growth and see how it looks. I assume the plants stretched before you placed them in the tent because stretch is a product of too little light. You dont get stretch and curl together unless you mess up the feeding and it seems all you have done is add cal/mag after it curled.
It would help to know what lights you actually have. Brand and model. You can take a photo of the model tag if its easier.
Welcome to the forum , we will certainly help you sort this out.

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Thanks to all of you for your comments and suggestions. The following are the bulbs I have in the canopy:

Two Shinestar 23w led 5000K 2500 lm

Three PBL 40w cfl 5500K 2400 lm

One Ecobulb 40w cfl 6500K 2800 lm

Four Ecosmart 14w led 3000K 1600 lm

I am going to put my clear cups in red solo cups to shade the roots. I also put a wet towel in the tent. The humidity has increased to almost 60.

Do you think I should continue using calmag while the seedlings are in soil?

Thanks for your help!


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No. Just plain water for now.
Do you use tap water or bottled/distilled or ?

Are you planning on buying a grow light?
You can certainly grow with enough bulbs but its going to be a pain in the long run.

To answer your questions, I do have holes in the bottom of the cups. I have been using distilled water.I do have a grow light with one MH for vegetative and one MH for flowering. They are 600w each. I decided to go with the cfls and leds to save money on electricity.

Should I be concerned about how small the plants are even though I planted the seeds three weeks ago?

They are small for that amount of time. Usually a bit bigger at two weeks from sprouting.
But they can recover fine.
If they turn out to be autoflowers they may be on the small side. But its good experience no matter what.

Similar thing happened to me. I lifted the light like you did (I think mine is up at 60cm now - or around tgat) and I reduced the light to 75%. Seems to be working for me so far.

Might be a good idea to not use clear cups and expose roots to constant light. Light exposure increases the likelihood of algae growth onto the surface of the roots, which will inhibit their ability to do their job, which is to uptake nutrients.

I agree with the other members you have a ph issue but ur plants are getting to lanky they need more light something that draws 240-300 watts from the wall depending on the size of ur tent

Exactly @Jungianstrain

I adjusted the ph of my distilled water before the last watering. Thanks
Does anyone else think my lighting is deficient? I am drawing 256 watts for a grow tent that is 2.5’ by 2.5’. I am putting out 21400 lumens. From my reading, this is sufficient for two lights
The light canopy I am using has the same bulbs on the right side as the left side and two in the middle. Yet, the plants on the right side are growing slanted. The plants on the left side are growing straight up towards the lights. The cups on the right side are in the same position relative to the lights as the left side. Any explanation? Any suggestions. I know from my reading that slanted growth could be a sign of insufficient lighting.