cause of leaves turning purple

[kaotik]

what causes a plants leaves to start turning purple?

i was talking to my buddy, and he mentioned some of his leaves are turning purple.
*these are mostly seeds i gave him.. there may have been a few purple kings in there, but i highly doubt it.

i remember reading about some nutrient defficiency years ago.. i mentioned maybe N.. but i'm second guessing myself now, as i'm not a great grower to begin with, and learnt most of my knowledge long ago.

he doesn't care. but it's bugging me now, so i turn to you. (i know it could possibly be many things, but is that an effect of a deffiency?)
thanks


*hate to post this. but it's bugging the heck outta me, and i couldn't find anything with searches.

[Geter-D1]

cold weather type of plant deficiencies hope this helps. Potassium (K)
Potassium is involved in maintaining the water status of the plant and the
tugor pressure of it's cells and the opening and closing of the stomata. Potassium is required in the accumulation and translocation of carbohydrates. Lack of potassium will reduce yield and quality.
Potassium deficiency:
Older leaves are initially chlorotic but soon develop dark necrotic lesions
(dead tissue). First apparent on the tips and margins of the leaves. Stem and branches may become weak and easily broken, the plant may also stretch. The plant will become susceptible to disease and toxicity. In addition to appearing to look like iron deficiency, the tips of the leaves curl and the edges burn and die.
Potassium - Too much sodium (Na) displaces K, causing a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather.

Figure 13

Figure 14

Potassium (K) Toxicity:
Usually not absorbed excessively by plants. Excess potassium can aggravate the uptake of magnesium, manganese, zinc and iron and effect the availability of calcium.

Magnesium (Mg)
Magnesium is a component of the chlorophyll molecule and serves as a cofactor in most enzymes.
Magnesium (Mg) deficiency:
Magnesium deficiency will exhibit a yellowing (which may turn brown) and interveinal chlorosis beginning in the older leaves. The older leaves will be the first to develop interveinal chlorosis. Starting at leaf margin or tip and progressing inward between the veins. Notice how the veins remain somewhat green though as can be seen in figure 15.
Notice how in figure 16 and 17 the leaves curl upwards like they're praying? They're praying for Mg! The tips may also twist.
This can be quickly resolved by watering with 1 tablespoon Epsom salts/gallon of water. Until you can correct nutrient lockout, try foliar feeding. That way the plants get all the nitrogen and Mg they need. The plants can be foliar feed at ½ teaspoon/quart of Epsom salts (first powdered and dissolved in some hot water). When mixing up soil, use 2 teaspoon dolomite lime per gallon of soil.
If the starting water is above 200 ppm, that is pretty hard water, that will lock out mg with all of the calcium in the water. Either add a 1/4 teaspoon per gallon of epsom salts or lime (both will effectively reduce the lockout or invest into a reverse osmosis water filter.
Mg can get locked-up by too much Ca, Cl or ammonium nitrogen. Don't overdo Mg or you'll lock up other nutrients.
Figure 15

http://www.marijuana-seeds.net/Thanks/ThankYou.htm

[tn_toker420]

I've also actually been wondering about this...But in this case, some of the new growth is purplish...Right in the middle of the tops...This is before showing sex also if that matters...But is nothing like the pics, fan leaves are usual color , maybe a few yellowing spots...

[OldSkool]

Kaotic, are his plants otherwise healthy? What is his reason for concern, other than the purple coloration?
It's normal in alot of Indica strains.

[kaotik]

was over a year ago m8.. i don't even remember posting this lol

[ozzydiodude]

stoners were here might as well while here

[2Dog]

I'll smoke with you Ozzy..watching operation repo..pass that **** dude!