I saved this a long time ago, it helped me through some tough spots.

To use the Problem Solver, simply start at #1 below. When you think that you have found the problem, read the section and try to learn more about it. Diagnose carefully before making major changes.

1) If the problem affects only the bottom or middle of the plant go to #2
B) If it affects only the top of the plant or the growing tips skip to #10. If the problem seems to affect the entire plant equally skip to #6.

2) Leaves are a uniform yellow or light green, leaves die and drop, growth is slow. Leaf margins are not curled up noticeably>>> Nitrogen(N) deficiency. If not go to #3.

3) Margins of the leaves are turned up and the tips may be twisted. Leaves are yellowing (and may turn brown) but the viens remain somewhat green.>> Magnesium(Mg) deficiency. If not go to #4.

4) Leaves are browning or yellowing. Yellow, brown or necrotic patches, especially around the edges of the leaf, whick may be curled up. Plant may be too tall.>> Potassium(K) deficiency. If not keep reading.

5) Leaves are a dark green or red/purple. Stems and petioles may have purple/red on them. Leaves may yellow or turn under, leaf may drop easy. Growth may be slow and leaves small.>> Phosphorus(P) deficiency. If not go to #6.

6) Tips of leaves are brown, yellow or dead. Plant otherwise looks healthy and green. Stems may be soft.>> Over fertilization (especially N) Over-watering, damaged roots or insufficient aeration. Ocasionally due to not enough N P or K. If not go to #7

7) Leaves are curled under like a ram's horn and are dark green, gray or brown/gold.>> Over fertilization, too much N. If not go to #8

8) The plant is wilted even thought the soil is moist.>> Over fertilization, soggy soil, damaged roots, disease, copper deficiency(very unlikely) If not go to #9

9) Plants won't flower even though they get 12 hours of darkness for over 2 weeks.>> The night period is not completely dark. Too much Nitrogen. To much pruning or cloning. If not go to #10

10) Leaves are yellow or white but the veins are mostly green.>> Iron(Fe) deficiency. If not go to #11

11) Leaves are light green or yellow beggining at the base, while leaf margins remain green. Necrotic spots may be betwwn veins, leaves are not twisted.>> Maganese(Mn) deficiency. If not go to #12

12) Leaves are twisted, otherwise pretty much like #11.>> Zinc(Zn) deficiency. If not go to #13

13) Leaves twist then turn brown and die.>> The lights are too close to the plant. Rarely a Calcium(Ca) or a Boron(B) deficiency. If not you may just have a weak plant.

The Nutrients:

Nitrogen- plants need lots of N during Vegging, but it is easy to overdo it. Added too much? Flush the soil with plain water. Soluble nitrogen (especially nitrate) is the form that is most quickly available to the roots, while insoluble N, (like urea) first needs to be broken down by microbes in the soil before it becomes available to the plant. Avoid excessive ammonium nitrogen, which can iterfere with other nutes. Too much N delays flowering. Plants should be allowed to become N deficient late in flowering for best taste and flavor.

Potassium- Too much sodium (Na) displaces K causing a K deficiency. Sources of high salinity are baking soda, too much manure, and the use of water softening filters. If the problem is Na, flush the soil. K can also get locked up from too much Ca and possibly cold weather.

Phosphorous- Some deficiency during flowering is normal, but too much shouldn't be tolerated. red petioles and stems are a normal genetic characteristic for many varieties, plus it can be a co-symptom of N K and MG deficiencies, so red stems are not a fool proof sign of P deficiency. Too much P can lead to an iron deficiency.

Magnesium- Mg deficiency is pretty common since marijuana uses lots of it and many fertilizers don't have enough of it. It is easily fixed with teaspoon/gallon of epsom salts or foilar feed at teaspoon/quart. When mixing up soil use two teaspoons of dolomite lime per gallon of soil. Don't over do the Mg, you will lock out other nutes.

Iron- Fe is unavailable to plants when the pH of the water of soil is too high. If deficient, lower the pH to 6.5 (for rockwool about 5.7) and check that you are not adding too much P, which can lock up Fe. Use chelated Fe for maximum efficency. Chelated iron may read like this, iron EDTA. Too much Fe without adding enough P can cause a defieciency of that nute.(P)

Maganese- Mn gets locked out when the pH is too high and when theres too much Fe. Use chelated Mn.

Zinc- Also gets locked out due to high pH. Zn, Fe, and Mn deficiencies often occur together and are usually from a high pH. Don't over-do the micro-nutes. Lower the pH if that's the problem. Foilar feed if it looks really bad. Use chelated zinc.

Check Your Water- crusty faucets and shower heads mean your water is hard, usually due to too many minerals. Tap with a TDS of more than 200ppm is hard and should be looked into. Ask your local water company for an analysis of the water in your area. This is a common reqeust and should not raise any eyebrows. Regular water filters will not remove or reduce a high TDS level. There are methods available that will, but they are costly.(R/O, distillers and de ionizers)

General Feeding Tips- Pot plants are very adaptable, but a general rule of thumb is to use more N and less P during vegging and the exact opposite in flowering. For the veg try a N P K ratio of 10:7:8 which of course is the same as 10:14:16. Flowering plants need about 4:8:8. Check the pH after adding the nutes. If you use a resivoir, keep it circulating and change it every two weeks.
A general guideline for TDS levels is as follows:
Seedlings= 50-150 PPM
Unrooted clones= 100-350 PPM
Small plants= 400-800 PPM
Large plants= 900-1800 PPM
Last week of flowering= taper off to plain H2O.
These numbers are just a guideline and actual levels can can be changed by many factors. Certain nutes are "invisible" to meters, especially organics, so use TDS level only as an estimate of actual levels.

PH- The pH of water after adding the nutes should be around 5.9 - 6.5. In rockwool 5.5 - 6.1
Generally speaking the micro nutrients (Fe Zn Cu) get locked out at a high pH above 7.0. While the major nutrients (N P K MG) can be less available in an acidic soil or water(below 5.0)
Tap water is often too alkaline. Soils with organic matter in them tend to get too acidic, dolomite lime will fix this right up.
Generally the more you pay the better the accuracy of any pH meter, although the water based color strips for aquariums are rather accurate and inexpensive.

Heat- If the lights are too close to the plant, the tops will be curled, dried and look burnt, mimicking a nute problem. Your hand should not get hot after holding it at the top of your plants for a minute.
Raise the lights/aim a fan at the hot zone. Room temps should be kept under 85F or 90F if you add additional CO2.

Cold- Cold weather below 50F can lock up phosporous. Some varieties, like equatorial sativas, don't take too well to cold. By keeping the roots warm, a plant can handle cooler temps than usual.

Humidity- Thin shriveled leaves can be from low humidity. 40- 80% is usually fine.

Mold and Fungus- Dark, patchy areas on the leaves and buds can be mold. Lower the humidity and increase the ventilation if mold is a problem. Remove any dead leaves whereever they are. Keep your garden clean. Prevention is the key.

Insects- White spots on the tops of leaves can mean spider mites underneath.

Sprays- Foilar sprays can have a magnifiying glass effect undr bright lights, causing small yellow, white, dead spots on the leaves which is often confused with a nute problem.

Insufficient light- Tall, stretchy plants are usually from using the wrong spectrum light. Cannibis needs good lighting to grow big, better yet, use the sun.

Clones- Yellowing leaves on the unrooted clone can be from too much light or the stem may not be firmly touching the rooting medium. Turn off CO2 until they root. Too much fertilizer can wilt or shrivel clones- plain tap water is fine.

Version 1.1 Feb 1998- distribution okay

If this helped, send a few dollars to NORML
Best of luck

Whew that's that, i gotta smoke now.
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