The Purple Leaves Mystery

Hello Forum.

Novice grower here with a couple of seasons under my belt. I have a late flowering Blue Dream strain that is showing purple leaves.

Foxfarm soil in 5 gal fabric pots.
Foxfarm Big Bloom for the first 8 weeks of flowering (3/4 strength).
Tiger Bloom Extra Strength for the last 2 weeks (3/4 strength).
Measly 150 watt HPS for veg and flower.
Trichomes look at least a week away from the harvest window.

Nights are around 43-52F, but another strain (Pink Napoli) has remained green despite having the same diet, temp and light schedule.

Phosphorous lockout? Genetics?

FYI, I rescued these plants from near spider-mite death in late vegetation. Frankly, I'm surprised they have produced anything at all.

Thanks,
Kinch

I would assume it's a combination of cold night time temps and the plants natural fall foliage. If you're 8 weeks into flower it's probably getting close to finish.

There could be a genitic element to it but in my experience, cold night temperatures will turn most strains purple. Is your pink strain as far along? Chlorophyll tends to mask the natural pigmentation in the plants so if the blue dream is further along and the chlorophyll levels might be in decline.

Attikus112 said:

I would assume it's a combination of cold night time temps and the plants natural fall foliage. If you're 8 weeks into flower it's probably getting close to finish.

There could be a genitic element to it but in my experience, cold night temperatures will turn most strains purple. Is your pink strain as far along? Chlorophyll tends to mask the natural pigmentation in the plants so if the blue dream is further along and the chlorophyll levels might be in decline.

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Yes, I've kept both at the same light-hour stage throughout. In fact, I was planning to harvest this weekend, but the trichomes don't have enough amber for me to be confident.

I'm concerned that the temps are triggering lockout.

Every blue dream I’ve smoked has purple hues mixed throughout the flower. I think it’s partially the genetics and partially the cool temps at night. Your plants look chronic!

Here is the Pink Napoli for contrast. Some browning on the fan leaf tips, but no purple. Pink Napoli also ended up much taller. The lack of N in the Big Bloom nutrients may be the cause of Pink's yellowing leaves.

I think I'll have time for one more Tiger Bloom feed before harvest in 7 days. Trichomes still lack amber.

Any plant with the genes will express color at those temps. My seedlings will show purple if I let the temp dip into the low 60s.

The only reason the pink Napoli isn’t purple to is genetics. I get purps if my temps drop into the low 70s.

Anthocyanins.

Phosphorus problem

Rob Roy said:

Anthocyanins.

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Had to look it up, but glad to see it is not some new and deadly parasite sucking the chlorophylic life out of plants.

Plus one for the Chicago Defender reference.

ebcrew said:

Phosphorus problem

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@ebcrew Do you think it is phosphorus lockout from the low temps? Can a more precise ph level make it accessible despite the temps?

Kinch said:

Hello Forum.

Novice grower here with a couple of seasons under my belt. I have a late flowering Blue Dream strain that is showing purple leaves.

Foxfarm soil in 5 gal fabric pots.
Foxfarm Big Bloom for the first 8 weeks of flowering (3/4 strength).
Tiger Bloom Extra Strength for the last 2 weeks (3/4 strength).
Measly 150 watt HPS for veg and flower.
Trichomes look at least a week away from the harvest window.

Nights are around 43-52F, but another strain (Pink Napoli) has remained green despite having the same diet, temp and light schedule.

Phosphorous lockout? Genetics?

FYI, I rescued these plants from near spider-mite death in late vegetation. Frankly, I'm surprised they have produced anything at all.

Thanks,
Kinch

View attachment 4826305View attachment 4826306View attachment 4826307

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Blue dream is known for the color contrast

Same as girl scout cookies. also depends on light sources type, intensity and nutrient feed

Written by Asia Mayfield
Purple is an exotic color in the cannabis world. Connoisseurs salivate over varieties that are saturated with rich, violet tones.
What gives cannabis its purple color? Plants are sculpted by the interplay between their genetics and their environment. There are many cultivars which are normally green or gold but will produce purple or pinkish hues under the right conditions.
Genetics
Purple cannabis gets its color from anthocyanins, a type of flavonoid that gives rise to purple, red, and blue tinges in flowers and plants. [1] These pigments are present in every part of the plant, although not necessarily in concentrations high enough to produce visible coloration.
Cannabis varieties that are rich with anthocyanins aren’t always purple. Their color depends on the level of pH. Anthocyanins appear reddish in acidic environments and purplish in neutral ones. [1]At higher pH, they lose their molecular integrity and break apart, causing no coloration at all. [2]
Most plantsproduce anthocyanins. They’re responsible for the color change of leaves. However, the plant’s appearance might not be altered until it enters its final flowering stage. [3] Pigments in the plant often appear brighter when they don’t have to compete with chlorophyll.
Environment
Research indicates that anthocyanin degradation is significant at temperatures over 75°F. [2] Therefore, it’s vitally important to keep purple cannabis varieties at room temperature. This is especially true after they have been harvested, as anthocyanin concentrations are mostly maintained in vivo by a dynamic expression and degradation process. [3]
Anthocyanin Extraction
Making purple extracts can be a somewhat difficult process, because of the temperature and pH restrictions. One way to work around that is with a rosin press, a solvent-less extraction process. The flower is compressed under heated plates before the cannabis fully dries. The vaporization of water protects the molecular integrity of the THC and anthocyanins from overheating.
Phil Salazar, inventor of the rosin process, has some advice.“A good range to press flowers is 200-230°F for 10-30 seconds, depending on variables like stability and terpene loss.”
References:

1. Khoo, HE, et al. “Anthocyanidins and anthocyanins: colored pigments as food, pharmaceutical ingredients, and the potential health benefits”, Food & Nutrition Research, 2017, Volume 61.
2. Laleh, GH, et al. “The Effect of Light, Temperature, pH and Species on Stability of AnthocyaninPigments in Four Berberis Species”, Pakistan Journal of Nutrition, 2006, Volume 5.
3. Niu, J., et al. “Anthocyanin concentration depends on the counterbalance between its synthesis and degradation in plum fruit at high temperature”, Scientific Reports, Volume 7.

Nice quote. Any thoughts of your own?

Kinch said:

@ebcrew Do you think it is phosphorus lockout from the low temps? Can a more precise ph level make it accessible despite the temps?

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Not sure ive never experienced temps that low. But i know that phosphorus cant be taken in in temps that low.