🌱 What to Do When Your Autoflowers Grow Tall and Don’t FlowerUpdated 3 months ago

Autoflowering cannabis strains are supposed to switch from veg to flower all on their own — usually within 3–5 weeks of sprouting. But sometimes, growers notice something strange: their “autos” keep growing taller and taller... with no signs of flowering. 😳

If you're seeing this in your greenhouse, especially with a strain like Green Crack Auto, don’t worry — here’s what’s happening and what you can do.

🚨 Why Are My Autoflowers Not Flowering?

If your plants are:

• Over 5–6 feet tall 🌲

• Still in vegetative growth after 5+ weeks 🕒

• Not showing pistils (white hairs) or pre-flower signs

...then it’s very likely your plants aren’t behaving like autoflowers. You might be dealing with:

1. Photoperiod traits in your seeds

Occasionally, an autoflower seed may express photoperiod behavior, especially in hybrid strains. These plants won’t flower until they receive 12 hours of darkness per day — usually in late summer (August/September outdoors).

2. Greenhouse light pollution

If you’re growing in a greenhouse near porch lights, floodlights, or with a non-sealed structure, that extra light can interrupt flowering in sensitive plants — even autoflowers that are acting like photos.

✂️ What Should I Do Now?

If you suspect your “autoflower” is actually acting like a photoperiod, here’s how to move forward:

✅ Top and train your plant

At 6+ feet tall, topping the main cola and using low-stress training (LST) can help reduce height, promote better airflow, and encourage multiple flower sites. 🌿

✅ Light dep if possible

If you’re in a greenhouse, try using a blackout tarp or covering to simulate 12/12 lighting. That can trigger flowering faster instead of waiting until fall. 🌓

✅ Be patient

If you can’t light-dep, plan on a September–October harvest. Focus on healthy growth, airflow, and pest/mold prevention in the meantime.

🧠 Bonus Tips for Beginners

• Don’t panic! Even if they weren’t true autos, your plants can still finish strong.

• Keep feeding on a vegetative nutrient schedule until flowering starts, then switch to bloom nutrients. 🌸

• Support large plants with stakes or cages to prevent toppling.

🌼 Final Word

While autoflowers are designed to simplify the grow, nature doesn’t always read the label. If your plant looks more like a tree than a timeline, you’re not alone — and you’re not doing anything wrong.

Still have questions? Our team of growers is here to help. Reach out anytime and we’ll walk you through it!