Black Runtz Strain Review: THC, Effects, Flowering Time & Yield

Black Runtz is an original QCS strain: a 70% indica, 30% sativa feminized hybrid (Black Diamond Sherbet × Runtz) that tests at 30 to 32% THC on its best phenotypes, flowers in 8 to 9 weeks and is ready outdoors in late September to early October. This Black Runtz strain review combines our specs, the real customer reviews, including the honest complaints, and what growers commonly report, so you can decide whether it suits your garden.

Black Runtz strain at a glance

What is the Black Runtz strain?

Black Runtz is an original QCS strain: Quebec Cannabis Seeds is its original breeder, and these are our own genetics, bred in Quebec since 2015 by a grower with more than 35 years of experience.

The Black Runtz strain is a 70% indica hybrid from Quebec Cannabis Seeds, built from Black Diamond Sherbet × Runtz. It is one of the strongest strains QCS offers and one of the most colourful. Runtz is the candy-sweet, fruity cross that took over the cannabis world in recent years, usually described as a blend of Zkittlez and Gelato. The Sherbet side brings earthier, spicier notes and a thick, dark frame.

On the plant, that cross shows up as deep purple to near-black flowers, especially in the final weeks of flowering. The colour is a big part of the appeal, and a customer who grew it said he was impressed by the colour and the strength.

A word on names: there are many Runtz-family crosses, and other seed companies sell their own Black Runtz with different parents and numbers. Other seed companies' versions may differ; the figures here are for the QCS version only.

Is Black Runtz indica or sativa?

Black Runtz is indica dominant: QCS lists it at 70% indica and 30% sativa. That tilt shows in a compact, sturdy plant indoors, with dense flowers and a calming effect, while the 30% sativa keeps the start of the experience bright and mood-lifting.

Outdoors, though, the plant can surprise you: one grower reported a 10-foot plant. If you want to learn what to expect from an indica-leaning profile, read our guide to what indica does to you.

Smell and flavour

QCS lists the flavour as earthy, spice and berry. The Runtz side brings sweet and fruity notes, and the Sherbet side contributes the earthier, spicier aroma. Many consumers describe Runtz-type strains as candy-like, which is why they became so popular.

Real growers do not always agree on flavour, though. One reviewer described the taste as neutral, but he enjoyed it enough to make cookies with it. Cure matters a lot with this type of plant: a slow dry and a few weeks in jars usually bring out far more flavour than a rushed job.

Black Runtz effects

QCS describes Black Runtz as deeply relaxing, with a euphoric, mood-lifting start, and recommends it as an evening strain. A customer wrote that it is strong but easy on anxiety. As with every cannabis strain, individual reactions vary, and nothing here is medical advice.

Because of its potency, newer users should start low. This is not a strain for casual first-timers: at the higher end of its THC range, a small amount goes a long way. Wait before taking more, and leave a quiet evening for it.

How strong is Black Runtz? THC content

QCS lists Black Runtz at 30 to 32% THC on its best phenotypes, which makes it one of the strongest strains we sell. CBD is not listed on the product page. The key words are "best phenotypes": seeds are genetically diverse, so some plants will test lower than others. One grower told us that some of his plants fell well below 32%, and on our page we say the same.

You may see other numbers online for Black Runtz from other companies, often in the mid-20s. Those figures describe their versions. For this one, the figures are the QCS figures. If you want to compare strong options, browse our THC over 25% seeds.

Growing Black Runtz: flowering time and yield

Indoors, Black Runtz is compact and sturdy, suited to a tent. It flowers in 8 to 9 weeks and yields up to 450 g/m². Outdoors it is typically ready between late September and early October and can give up to 550 g per plant. It clones easily. Colour comes through in the last weeks of flowering. QCS badges the strain beginner-friendly, but be aware that it is a plant with one weak point: stress.

Our product page is straightforward about the main challenge. Some Black Runtz plants can produce male flowers (the "bananas" growers talk about) when stressed. The page recommends: keep the light schedule strict with no light leaks, avoid large temperature swings and heavy late-flower training, feed steadily, check lower buds for male flowers from week five, and keep humidity low late in flower to prevent mould and mildew.

One reviewer saw this herm tendency in two separate crops and found the plants touchy, so it is best suited to growers who can keep a stable environment. Remember that "mold resistant" on our site means mold tolerant, and that a dense, purple flower still needs airflow.

What customers report

Black Runtz has ten reviews on our site and averages 4.9 out of 5. The page is more balanced than that headline number suggests, so here is the full picture.

• Colour and strength: a customer was impressed by the colour and the strength, and another grower highlighted the clone performance and the impressive trichomes at week five.
• Big plants: one grower produced a 10-foot plant and said all their plants performed as advertised. An outdoor grower had big plants that were still not ready on October 20 after more than nine weeks of flowering, with no mould or stress signs. They also noted that brown pistils are normal near harvest.
• Home grow results: a grower with two trained plants in 5-gallon pails harvested 17 ounces by the third week of September. He found it strong but easy on anxiety.
• Germination: a customer who ordered on a Sunday had every seed sprouted by Thursday, while another grower had one runt among three seeds.
• The honest complaint: one grower said some phenotypes fell well below 32% THC and that the plants tended to herm in two crops and were touchy to grow. He may try other strains. Two earlier reviewers also questioned whether the page figures were 30 to 32% or 21 to 24%, and QCS confirmed the 30 to 32% figure.

Is Black Runtz right for you?

Choose Black Runtz if you want a very high-THC, colourful, indica-leaning plant and you can keep your environment steady, with a strict light schedule and moderate training. It is a good pick for experienced consumers who want a strong evening strain with sweet, earthy flavour. It is a weaker match if your grow room has frequent light leaks or temperature swings, or if you want a mild effect.

Looking for something similar? Browse our feminized seeds or our THC over 25% collection. If you want a lower-THC, gentler option, read our review of Black Cherry OG.

Black Runtz: frequently asked questions

A note on the numbers in this article: harvest dates, flowering times and yields are ranges, not promises. They vary depending on growing conditions: the grower, the method and the season's weather. No strain is 100% mold resistant. How we set these numbers →

View Black Runtz seeds →