Plant problems and how to solve them

The Cannabis Grow Bible

by Greg Green

marijuana plant problems

Before we begin we should tell you what a chemical burn is. A chemical burn is what the plant suffers because of over-feeding. A chemical burn can be compared to a half-smoked joint. At the tip of the joint you have this shrivelled grey ash, in the middle you have the burn creeping towards new paper which leaves a pattern behind it, and then you have the part you have not smoked yet. A plant burn looks like this almost. The plant sucks up the water and the food. It distributes these elements to the leaves at the bottom first and then works it way up the plant. This process takes days to work as you know FROM WATERING and WHEN TO WATER! The damage starts at the tips of the leaf and slowly moves to the centre of the leaf, leaving behind it some crispy matter that flakes away between your fingers. This is what a chemical burn looks like. A nutrient problem does not look burnt. A nutrient problem looks like a cell collapse with discoloration. The part may wither and die, but it should not look burnt. That is major difference between a chemical burn and a nutrient problem. In time you should be able to tell the difference for yourself.

Also check your pH. If your pH is not right, then solve the pH problem before you go and do anything else.

A) Look at your problem and quickly search for any bugs. When you have completed this search, eliminate any bug problems by using the advice in the bug chapter. Also note the type of attack to make sure that it is not a bug problem AND is a nutrient problem, which can happen. Do your leaves look sucked and dry? Do you have any black dots on them like bugs? Try to tell the difference between a bug attack and a nutrient problem. Nutrient problems damage the plant on a somewhat consistent level. Bug attacks are less consistent in the damaged generated. They leave damaged patches everywhere on your plant.

If the problem seems to affects only the lower portion of your plant and or a bit of the middle then read B). If it is only effects the top of your plant and the tips then you should go to J). If the plant is covered with the problem then go to F).

marijuana plant problems

B) If your plant is in vegetative growth and the leaves are going very yellow, then you need more Nitrogen. If your plant is in flowering and you have stunted growth, yellow leaves and it looks to be dying then you need more Nitrogen. If your plant is in flowering and does not look like it is dying but looks red or dark green/yellow then you need to treat it with more P, which is Phosphorus. If these do not help then go to C.

C) If your plant has leaves that are curling up, twisting and are going yellow then check to see if your light is burning them or if the grow chamber has enough air circulation. If this is fine then you need to consider adding more Mg which is Magnesium to your plants. Epsom salts are good – 1/4 – 1/3 table spoon of Epsom salts to 3 gallons of water is fine. If you still have a problem go to D).

D) If the tips of the leaves turn brown and curl slightly then you are looking at a K problem which is Potassium problem. If not, move onto E.

E) Does your plant look wilted? Maybe you over- watered? If not, go to F.

F) The veins are green, but the leaves are yellow. This is an Iron problem, Fe. If not, move on to G:)

G) Leaves are not twisted but are yellow at the base. The tips are fine. This is a Manganese problem, which is (Mn). If not, move on to H).

H) Still haven’t solved it? Then flush your soil and find another type of plant food that has all of these. N, P, K, Ca, Mg and S. Get Epsom Salts and get a small canister of micronutrient. Iron, boron, chlorine, manganese, copper, zinc, and molybdenum. Try using a nutrient mixture that we have already mentioned before in the indoor feeding section.

Cannabis Grow Bible

41 comments to Plant problems and how to solve them

  • Anonymous

    I have a Bluedream problem. The new growth is bright, light green to yellow and all the new what would be terminal growth is shriveled and dying. The lower leaves have very prominent ridges. I flushed this morning, and treated with a bleach tea to rule out any easy fix problems. Can post pic if needed. It is in a veggie stage and the sibling has no signs of problem. 2nd generation plant

  • andrea parsee

    our buds our turning brown also starting to get seeds 3 weeks into flower not sure what is causing this or if anyone has any advice??? thank you in advance

  • Bluesmoke

    The whole top half of my plant is curling up and looks like it’s dying. The plants are still in their original sponge, but now in big pots. Still in the veg. State, but seem to just grow leaves and curl. Leaves are showing some yellow on the mature ones. Is this because the sponge? The soil, is not overly wet at all

  • Anonymous

    Poop your pants and then go into the grow room. The smell cures deficiencies instantly.

    • Anonymous

      This is true. Tried it before and it worked like a charm, just make sure you make a real mess in your pants you need a good strong odor. Corn is a bonus.

      • Anonymous

        Ive also had this work amazingly well. Took a huge dump in my pants and wandered around the grow room for a few hours, the plants seem to feed off the fumes from your shitty pants.

  • 2tone

    my plants are 1 week from cuming dawn and av just seen thay have got leaf beetle wa will hapen to my bud wen its drying?

  • Anonymous

    My fan leaves are drying up in crumbling during the third week of flowering stage is that normal?

  • beautiful

    ok well idk whats wrong with my plants this is not my first time growing or second but this is my first time with this system and i need help quick because this is killing my plants one by one

  • Dennis

    Hi;I Help. I had someone looking after my autoflowering plants. She quit. Now I do not know how long these plats have been growing. Some are tiny and do not look good, some yellowing leaves, some thin and tall, some look great and large buds forming. But I have no idea when I should harvest. How do I tell when they are ready??

  • confused

    okaykI have a plans it’s about a year and a half old when it first started was like 3 months old it started buding and then it stopped I moved it outside during the summer time and its not doing nothing now it’s not flowering but it’s grown really tall how do I fix that I want it too bud again

  • Gman

    under watering is better for your plant than over watering. the article states that any yellowing or discoloration of leaves can be a multitude of issues. I.e: nutrient Burn, High Temp in grow room, Lack of air circulation. A good flush once or twice during your grow will help to keep any residue build up in soil or substrate down so i would advise a flush for a day maybe 2 before carrying on with adding your feeds. After flushing try using half the amount of feed you were using before you flushed, this should help balance things out.

  • Anonymous

    I cut a new branch by accident while topping.. Should I cut the one across from it also? To even it out

    • pooopn

      yes and no, I too was once young and i accidrntly farted on my plant. So I took a dump on my pancakes…Now I drink some piss and wash down that turd!

  • Jayz

    Wow yall need to rethink growing.. If u can’t grow a olant without problems u shouldn’t grow at all.

  • Anonymous

    My 2 week old plant is wilting burnt at the tip what do I do

  • chrissy

    Ok i have a critical jack herer gping seedling working on its 4th or 5th node. But the things is all of jer new growth is gping crunchy. Tje leaves wjere its jard like that os still green bit crunchylike i said no discolorations except the ywllow tips on the first leaves that come out the aingle finger leaves. So can anyone help me out? I really cpuld use it email me and help me try to save my baybayuy iys a feminised seed by the way going on i think 3 weeks from soil to popping .

  • Anonymous

    What’s the best feed to use as am starting to change 12 to 12 to flower but my leaves are looking yellow at the tips so want a good all rounder to sort the problem out plus think av been over watering so av slacked of abit any help would be good

  • concerned

    My plant is 1 1/2 month and about 2 foot tall. Well here recently the top leaves look like they are having problems fanning out properly.. Also the bottom leaves have few yellow spots around the edging n a few holes like a bug has gotten a hold of it with yellowing around the holes. What do I need to do to fix this immediately.

  • GardenConnection

    All of you having curling leaves and browning buds need to get a 50x or higher scope and look and see if you have RUSSET MITES. These microscopic bugs have hit us hard the last 2 years in northern cali…..Treatments seem to be sulfur fungicides, and mycotrol-o. Hope this helps.

  • janr

    Wow e got leaves that are turning yellow w/ black dots like overnight. Is it too much water? My soil is organic and Jude purified water and once a week trace minerals from a well. The plant is 32 days old and I have also been topping it. Is topping a good thing? It sure grew fast t except for the leaves it is moving right along. Thanx for the help:)

  • wes

    Hey I’m growing for the first time so I’m not real sure what I’m doing. My bottom leaves are wilting and everything up top is turning kind of a light green color through the middle. Any thoughts or suggeztions?

  • rich

    Plant- blue mystic, indica dom. 1 1/2 old using potting soil for medium with very low nutes in it. have not supplemented yet cause plant looks very healthy overall but the secondary shoots sprouting r very droopy. ive been watering once a week so I don’t believe its due to overwatering. could this be a nute def. or something else

  • jason

    My leaves are turn in red at the tips then yellowing and dying also the stems are red as well what the problem and what do I do helppp??????

  • Jc

    Hi I have a ? For you pros out there I have autos going and the bottoms seem to be full and ripe while the middle and top don’t seem even close what could this be any help would be awesome

  • teddy

    Will my girls recover if they have root rot? They are very small for there 6 weeks alive.some wilt badly some seam ok someday and some are very strangely curling up but not like claw more long ways. What can i do?

  • Anonymous

    Reduce the hours and they will begin to sex… Water the whole plant not just roots .. And allow to dry

  • Miss London

    Hi there,

    I am almost losing a couple of plants from wilting. They are on vegetative state, no bigger than 30cm tall. The soil felt parched dry, even crumbling but the plants were just fine, but still I decided to water them. I’ve added a teaspoon of water straight into the roots of each plant, and they all wilted.
    Before that I haven’t watered them for over two weeks. I decided to water them as they weren’t growing as fast as I expected.
    It’s my first grow, so one more rookie question:
    How long before I can start watching for the plant’s sex? I planted those plants 60 days ago more or less, but I cannot find anything that can identify their sexes yet? Is it too early?

  • Debbie

    my girls were doing so good tell about couple weeks ago the lower branches are getting long and but leaves are tiny and curly.

  • lbezphil2005

    Look, most of you are overwatering – a cannabis plant has to dry between waterings, so when you stick a finger into the soil and pull it out the dirt doesn’t stick to it – if it does its still too wet!! in a 3 gal smart pot I might water every 2 or 3 days during flower, that’s it. cannabis needs good drainage – if the medium stays too moist too long you will get root rot. you guys whose plants are turning brown and crap, that’s the reason. too much moisture and too much feed, you’ve burnt your plants to a crisp. keep it simple, less is more – if the bottle says 5ml per gal make it 1 to 2ml at first until you see how your plants react – not all plants are heavy feeders, the more sativa the less they like nitrogen. do some reading, join a cannabis grow forum like grasscity or icmag or skunkmag, I don’t care – just educate yourself on what you are doing. growing cannabis is fun, challenging, and when its finishing pretty damn awesome – I have seen some of the most beautiful plants, turning from green to copper to a brilliant reddish purple, deep dark almost black purple, to a light almost lemony red with pink trichomes. when you learn what you are doing and give the plant love – not sit and think money money money but love the plant for what it does, and it will give back 10 fold. I have yet to have a bad plant.

  • robert wilson

    Will a neighbors security light effect the flowering stag? The bottom of my plant looks verygood and the litte bit of the plant that is gettig the light isgreen and no pistils?!

  • Derek

    I’ve been using Ph perfect it works awesome. I had someone water my plants they didn’t get the concept and added Ph down anyways. Now all my plants are curled in badly they had a few weeks till they would go in to flower. Now I’m not sure if they make it. Please help!!

  • Janedoe

    HELP! My auto flower is 6 weeks old and all of a sudden the leaves started to droop. The next day they were way worse, curled and dry. All over. There hasn’t been any changes. It’s as if it’s dried right out but it shouldn’t be. I watered it last night, then again today. What could be the problem?

  • A.C.

    I have the leaves problem on some plants, (not all)BUT…I am 6 weeks into the flowering stage and some of my buds are turning brown in the middle…what am I doing wrong ?? Any thoughts or help ??

  • tim c

    what should the high and low for ppm be ?

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