How to Grow Purple Weed Plants

A purple weed plant is a stunning sight, with shades of violet, indigo, and lavender adorning its leaves and buds. This pigmentation is sought-after among growers and tokers, but with the right genetics, achieving it has never been easier.

Purple weed is an interplay of genetic and environmental factors. As long as you have the know-how, it’s straightforward to obtain.

Its beauty isn’t just skin deep. The pigments responsible for the plant’s striking coloration also provide potential health benefits and enhance the flavor profile. Visual appeal, delicious aroma, and feel-good effects: this cannabis is a delight for all five senses.

Keep reading to learn what makes weed purple and how to get it at home. From strain selection to environmental control, we discuss all you need to raise vibrant plants at home.

The science behind purple weed: what makes weed purple?

Before we dive into a scientific explanation of what makes weed purple, it’s important to mention that some plants you see in pictures may not be violet. This discrepancy is because many shots of regular cannabis plants are taken under a purplish LED light, which gives them that hue.

These violet lights are used in the cultivation process and are said to help your plants grow better than blue ones. However, they don’t influence the color of the resulting buds.

Why is some weed purple?

All plants have natural pigments, such as chlorophyll and anthocyanins, that give them their color. What makes weed purple is the dominant presence of the latter rather than the former substance.

Typically, most plants use chlorophyll, which helps them photosynthesize and is responsible for their green hue. When this pigment is absent, plants turn to anthocyanins, which are part of a larger class of substances known as flavonoids.

Purp weed plants get their hue because flavonoids can change the colors of plants if it’s present. 

Although the word “cyan” in the name implies that anthocyanins are blue, they give plants a range of colors depending on the pH. If the pH is acidic, you’ll see red, while at the other end of the scale, you’ll get blue plants.

Purple weed is the result when the pH level is more neutral. This natural phenomenon typically occurs in the fall when chlorophyll breaks down and no longer dominates the other flavonoids. When anthocyanins prevail, plants have the potential to transform from green to other beautiful shades, like purple.

However, getting a purple marijuana plant by this method also depends on its genetics which determines which flavonoid is dominant. Without the right type of pigments and the proper amount, you can force a cannabis plant to turn purple.

What parts of cannabis can turn purple?

Purple weed plants come in numerous hues, from light lavender to deep violet. The buds may have accents or be completely purple, depending on the anthocyanin concentration. Pistils and trichomes may take on a pinkish hue.

Note: Violet pigmentation is desirable in certain parts of the plant, but stems turning purple is not a good sign. This symptom indicates a lack of oxygen, nutrient deficiencies (especially calcium and magnesium), or disease. It can stunt growth and reduce yields.

Knowing what should turn purple is crucial for successful cultivation. Let’s see which plant parts those are, what they do, and how they usually look.

Pistils

Pistils are delicate hairs that protrude from the calyxes of female cannabis plants. They are a crucial component of the reproductive system, protruding from the calyxes in the flowering stage.

The state of these structures indicates plant health and progress in flowering. They commonly start as straight and white, although some strains have pink or red pistils in early stages. They usually go yellow, orange, then reddish-brown when harvest-ready.

In addition to the importance of pistils for reproduction and ripeness, they contribute to the overall visual appeal. They can make the bud seem fiery orange, yellow, red, or purple.

Purple pistils on weed are rare and desirable traits. They emerge due to anthocyanin contents and can range from pink to maroon. The color shift may occur very early, but sometimes only becomes prominent after 4–6 weeks of flowering.

Calyxes

Calyxes are small, pod-like organs that comprise the female flowers and contain the ovules that eventually become seeds. If the plant remains unpollinated, they ooze the sticky, sweet-smelling trichomes.

These organs are green while young and develop color splashes with age. In purple cannabis, they can take on pink, lavender, or deep violet hues. They may completely change color, have tinges, or develop a gradient look.

Leaves

Leaves are an essential element of cannabis anatomy and physiology. They are the primary site for photosynthesis and play a vital role in plant health and growth.

Marijuana has two leaf types. Sugar leaves are the smaller structures that surround the buds and have trichome coatings. Fan leaves are larger and grow from the stem and branches. They absorb light and facilitate photosynthesis.

Healthy leaves are usually dark green while young and paler with age. A purple cannabis plant can develop subtle shades of violet, red, or blue on the foliage. The blades may also appear darker green and have purple veins.

Trichomes

Trichomes are mushroom-like crystals that emerge near the bud sites. These structures protect plants from pests and contain psychoactive, medicinal, and fragrant cannabinoids and terpenes. They develop to capture any possible airborne pollen.

Young trichomes are transparent. They turn cloudy while maturing, become milky white, and start going amber at the ideal harvest time.

Trichomes themselves don’t typically turn purple, as their color doesn’t depend on pigments. They sometimes take on the pink or violet hue from the surrounding plant tissue and develop a tinge. In that case, they may exhibit pink, red, or purple shades.

There’s an exception, thanks to modern breeding. Some exotic purp strains have purple trichomes or tints independent of the surrounding tissue. They’re rare and exquisite.

The secrets of growing purple weed

We arrive at the meat and potatoes of this guide: how to grow purple weed.

While it may be tempting to use food dye to get a vibrant hue, this leads to fake, modified violet plants that may be unsafe for smoking. Avoid potentially harmful shortcuts, but you can consider trying products like Purple Maxx to assist your journey of color-seeking.

Several factors influence the coloration of your cannabis, most importantly genetics, temperature, light, and nutrient availability. While no single factor will do the trick, combining them increases the odds of accentuating these colorful traits in certain strains.

Opt for the right seeds

A purple weed plant can’t emerge from just any seed. It’s possible but unlikely to coax these hues out of cultivars without the genetic predisposition. You’re more likely to be successful with strains known for purple phenotypes.

The ability to produce anthocyanins is genetically determined. Some strains produce more pigments than others, and some may not have them at all.

To find purple cultivars, start by looking at strain titles and lineages. Marijuana with “purple” or “lavender” in the name is a safe bet. Strains with violet parents or ancestors are another suitable option.

Modify the temperature

While discussing how to make weed purple, we must zero in on the temperature. Cooler weather in flowering stimulates anthocyanin production, coloring the leaves and buds.

Temperature drops signal that winter is coming, and the plant responds by producing more anthocyanins as a protective mechanism. This pigment protects the plant from the harmful effects of UV radiation and other environmental stressors.

This response usually occurs after the vegetative stage, sometimes even late into flowering. So, keep the climate warm with 70–85°F during the day and 60–70°F at night in vegging.

During the flowering stage, the ideal temperature range for purple weed is 60–70°F at night. A differential between day and night can also stimulate anthocyanin production. We recommend a 10–15°F difference between day and nighttime temperatures.

Provide concentrated light

Lighting is another essential factor for growing purple weed. In particular, high-intensity light can promote the production of anthocyanins in cannabis and deepen its coloration.

Besides coloring the buds and leaves, concentrated light exposure can cause some cannabis plants to develop pink pistils. This effect is rare but occurs in strains predisposed towards pink or red coloring.

One way to achieve concentrated light is with full-spectrum, high-powered LED lamps, which provide intense lighting that penetrates the canopy.

Be careful when using concentrated light, as excessive exposure can harm plants and hinder yields. Start with lower intensity and gradually increase it, monitoring your garden for distress signals.

Consider soil characteristics

Growing purple weed also depends on the composition and chemistry of your medium. Specifically, soil nutrients and pH levels affect the uptake and availability of various compounds that contribute to coloration.

Ensure your soil is rich in phosphorus, potassium, calcium, and magnesium, known to encourage anthocyanin. You can enrich it with organic materials, like bone and kelp meal. Add them with caution to avoid plant damage and be patient, as they need time to break down.

Tip: Don’t fall for the ruse of violet-tinted fertilizer. While it makes water purple, it won’t affect the color of your buds.

Additionally, maintain a pH of 5.8–6.2 to maximize nutrient availability and promote optimal coloration. Anthocyanins are soluble in acidic environments, and low pH facilitates absorption.

Over-fertilizing or over-acidifying your soil may result in nutrient burn. For example, soil under 6.0 pH can cause a calcium lockout and brown spots on the foliage. Monitor the nutrient and pH levels to maintain a balanced environment.

In a nutshell

Purple cannabis combines genetics with purple traits with specific conditions. Maintain the appropriate temperature and drop it to enhance the coloration. Use the right lighting, ensure the correct pH level, and provide a proper balance of nutrients for the best results.

Knowing how to make weed purple doesn’t only boost the bag appeal. It can also leave you with prettier buds with unique flavors. Why not give it a shot?

Visit our shop for a wide selection of seeds of purple strains. Set yourself up for success with the highest-quality genetics, and follow our tips to beautify your harvests.

7 popular purp weed plants

Now that you know genetics matter and selecting the correct strain is the key to growing purple marijuana, here’s a list of some of the most popular purple seeds you can choose from. In addition, we’ve summarized the key traits of each strain for your convenience.

Grandaddy Purple (GDP) Regular

One of the most popular purple weed plants on the cannabis scene.

• Type: Mostly indica
• THC: 21%
• CBD: 0.3%
• Top reported effects: Relaxed, calming, sedative 
• Top reported flavors: Grape, earthy, berry
• Flowering time: 8–10 weeks
• Difficulty: Beginner
• Yield: Indoor 19.4 oz./m² Outdoor 17.6 oz./plant

Grandaddy Purple (GDP) Feminized

A variant of the GDP purple weed that’s easy to grow without the hassle of removing males.

• Type: Mostly indica
• THC: 22%
• CBD: 0.4%
• Top reported effects: Happy, focused, euphoric 
• Top reported flavors: Grape, berry, citrus
• Flowering time: 10–12 weeks
• Difficulty: Beginner
• Yield: Indoor 17.6 oz./m² Outdoor 17.6 oz./plant

Purple Urkle Feminized

This purple cannabis strain is one of the parents of GDP.

• Type: Mostly indica
• THC: 22%
• CBD: 0.6%
• Top reported effects: Happy, focused, euphoric 
• Top reported flavors: Grape, berry, earthy
• Flowering time: 8–10 weeks
• Difficulty: Beginner
• Yield: Indoor 10.58 oz./m² Outdoor 14 oz./plant

Purple Kush Feminized

This legendary purple marijuana is popular among smokers and growers.

• Type: Mostly indica
• THC: 19%
• CBD: 0.6%
• Top reported effects: Euphoric, relaxed, uplifted 
• Top reported flavors: Spicy, grape, berry
• Flowering time: 6–8 weeks
• Difficulty: Easy
• Yield: Indoor 14.1–17.6 oz./m² Outdoor 21.1 oz./plant

Purple Thai Feminized

This purp weed sativa is a descendant of Chocolate Thai and Highland Oaxacan Gold.

• Type: Mostly sativa
• THC: 21%
• CBD: 0.3%
• Top reported effects: Focused, happy, hungry 
• Top reported flavors: Chocolate, coffee, nutty
• Flowering time: 12–14 weeks
• Difficulty: Easy
• Yield: Indoor 22.9 oz./m² Outdoor 35.2 oz./plant

Purple Haze Feminized

A sativa-dominant strain, this purple weed is the result of a cross between Purple Thai and Haze. 

• Type: Mostly sativa
• THC: 18%
• CBD: 0.3%
• Top reported effects: Creative, euphoric, giggly 
• Top reported flavors: Berry, spicy, earthy
• Flowering time: 8–10 weeks
• Difficulty: Easy
• Yield: Indoor 14.1 oz./m² Outdoor 14.1 oz./plant

Purple Punch Feminized

This purple cannabis strain is the offspring of GDP and Larry OG.

• Type: Mostly indica
• THC: 23%
• CBD: 0.7%
• Top reported effects: Happy, creative, euphoric 
• Top reported flavors: Berry, citrus, earthy
• Flowering time: 6–8 weeks
• Difficulty: Easy
• Yield: Indoor 15.87–19.4 oz./m² Outdoor 17.6–21.1 oz./plant

FAQs

Do you have additional questions or seek quick information about purple cannabis? Our expert team has compiled a comprehensive list of frequently asked questions and answers.

How do you make purple strains more purple?

Are you looking to add some serious wow factor to your marijuana garden? You can enhance plant coloration by lowering nighttime temperatures, reducing pH, and adding phosphorus and potassium.

The cold can trigger the development of purple pigments, as well as added PK amounts and a 6.0 pH level. You can also increase the light intensity to get the color production going. These factors hinge on the existence of anthocyanins but could take the hues from faint to vivid.

Are purple strains stronger than green?

Purple buds are usually less potent than green ones. The unique flavors and coloration could amplify your smoking experience in other ways. That said, the cannabinoid and terpene profiles determine the strength of a strain. They depend on genetic and growing conditions, not colors. The primary difference between green and purple cannabis is visual.

What nutrients can make weed purple?

To ensure your cannabis grows healthy and strong, provide a balanced ratio of all essential macro and micronutrients. While phosphorus, potassium, calcium, and magnesium may support the coloration, avoid overdoing it. Good store-bought solutions include Humboldt’s Purple Maxx.

You can use gentle organic phosphorus and potassium to promote purple pigmentation. Bone meal, kelp meal, and rock phosphate are excellent sources of these nutrients and can enhance the coloration without burning the plant.

What are some common mistakes to avoid when growing purple weed plants?

The internet is teeming with flawed tips on how to grow purple weed. Frequent ones include increasing nitrogen levels, air deprivation, and ice water flushing. These techniques can cause unhealthy plants and decreased yields of low-quality buds.

What is the best way to germinate purple weed seeds?

Seeds of purple cultivars don’t behave differently than green ones. They respond best to the paper towel germination method.

Place your seeds between moist paper towels in a dark space at 70–80°F. Let them sit for five days, checking them daily and removing all that sprouted taproots. Sow them root-side first in a lightly fertilized medium to launch the seedling stage.