After testing hundreds of autoflower strains—from Northern Lights Auto to Gorilla Glue Auto—the single biggest mistake I see collectors make is treating them like photoperiods. Autoflowers are a completely different genetic beast, and their nutrient needs are far lower. Overfeeding is the #1 reason autoflower grows fail.
This guide explains exactly what, when, and how to feed your autoflowers for optimal results, backed by real-world testing data.
Quick Answer: Autoflower Nutrient Basics
✓ Start with less: Use 1/4 to 1/2 the recommended dose for photoperiods
✓ No nutrients for 2-3 weeks: A good quality potting mix has enough food for the seedling stage
✓ Avoid “hot” soils: Soils rich in manure or slow-release nutrients will burn autoflowers
✓ Focus on bloom nutrients: Autos have a very short veg phase, so they need bloom nutrients sooner
✓ Water is key: Proper pH and clean water are more important than heavy feeding
After testing hundreds of autoflower strains—from Northern Lights Auto to Gorilla Glue Auto—the single biggest mistake I see collectors make is treating them like photoperiods. Autoflowers are a completely different genetic beast, and their nutrient needs are far lower. Overfeeding is the #1 reason autoflower grows fail.
This guide explains exactly what, when, and how to feed your autoflowers for optimal results, backed by real-world testing data.
Quick Answer: Autoflower Nutrient Basics
✓ Start with less: Use 1/4 to 1/2 the recommended dose for photoperiods
✓ No nutrients for 2-3 weeks: A good quality potting mix has enough food for the seedling stage
✓ Avoid “hot” soils: Soils rich in manure or slow-release nutrients will burn autoflowers
✓ Focus on bloom nutrients: Autos have a very short veg phase, so they need bloom nutrients sooner
✓ Water is key: Proper pH and clean water are more important than heavy feeding
❓ Frequently Asked Questions
Do I need special “autoflower” nutrients?
No. Standard cannabis nutrients work fine, just use them at a much lower dose (1/4 to 1/2 strength). The “autoflower” branding is mostly marketing. Focus on quality base nutrients and proper feeding discipline.
What are the signs of overfeeding an autoflower?
Look for dark green, waxy leaves; yellow or brown leaf tips (nutrient burn); and curled or claw-like leaves. If you see these, flush with plain water and reduce feeding strength by half.
Can I grow autoflowers in organic living soil?
Yes, but the soil must be well-composted and not too “hot.” A super-soil mix can work well as it releases nutrients slowly, but avoid adding raw manure or heavy fertilisers. Start with light organic soil like BioBizz Light Mix for best results.
What pH should my water be for autoflowers?
Aim for 6.0-6.5 for soil and 5.8-6.2 for coco coir. Correct pH is more important than heavy feeding, as it allows the plant to absorb the available nutrients. Hydroponic growers should target 5.8-6.0.
Do autoflowers need Cal-Mag?
Sometimes, especially in coco coir or with LED lights. If you see yellowing between the leaf veins (interveinal chlorosis), a light dose of Cal-Mag (0.5ml/L) can help. Add it on a separate day from your main feed. Learn more about LED growing techniques.
Is it better to underfeed or overfeed an autoflower?
Always better to underfeed. An underfed plant can be corrected with a light feed in the next watering cycle. An overfed and stunted autoflower will never recover its full potential due to the short lifecycle.
How often should I feed my autoflower?
Typically, you feed with every other watering in soil: Feed → Water → Feed → Water. This helps prevent salt buildup in the soil. Coco coir growers feed with every watering at lower strength. Hydro systems feed continuously or daily.
My autoflower leaves are yellowing, should I add more nutrients?
Not necessarily. Yellowing can be caused by overwatering, incorrect pH, or nutrient lockout, not just deficiency. Check your watering schedule and pH first before adding more food. See our troubleshooting chart above for specific diagnoses.
What PPM should I feed autoflowers?
Seedling (weeks 1-2): 0-50 PPM
Veg (weeks 3-4): 200-400 PPM
Flowering (weeks 5-8): 400-550 PPM
Late flower/Flush (weeks 9-10): 0-50 PPM
These are conservative ranges. Start at the low end and increase only if plants show hungry signs (pale green, slow growth).
Can I use bloom boosters on autoflowers?
Yes, but with extreme caution. Use only during weeks 6-8 at 1/4 recommended strength, maximum once per week. Products like Advanced Nutrients Big Bud or Canna PK 13/14 can improve density but will cause lockout if overused.
What nutrients do fast-flowering autoflowers need?
Fast-finishing strains (8-week varieties like Lowryder genetics) need even lighter feeding since they have less time to process nutrients. Stick to 1/4 strength throughout and skip bloom boosters entirely.
Final Thoughts: Let the Plant Guide You
After 300+ documented autoflower grows, the single most important lesson is this: watch your plant, not the feeding chart.
Every strain is slightly different. Sativa-dominant autos like Amnesia Haze Auto tend to be lighter feeders. Indica hybrids like Purple Kush Auto can handle slightly more. Your water quality, light intensity, and environmental conditions all affect nutrient uptake.
Start conservatively, observe daily, and adjust based on what you see. Healthy autoflowers have:
- Light to medium green leaves (not dark, waxy green)
- Vigorous vertical growth
- No burnt or yellowing tips
- Praying leaves (angled upward toward light)
Ready to start growing? Check out our complete range of autoflower seeds or dive deeper with our complete guide to autoflowers.
Related Guides:
- Autoflower vs Photoperiod: Complete Comparison
- Do I need to see amber trichomes before harvest?
- Choosing the best strain for you- a guide to the lineup
Disclaimer: This guide is for educational purposes for collectors and enthusiasts. Sacred Seeds sells cannabis seeds as collectible souvenirs. Germination and cultivation may not be legal in your jurisdiction. Always check local laws.
