Understanding the early and late signs of nutrient deficiencies in cannabis, particularly nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, and manganese, is critical for successful cultivation. Moreover, a well-balanced nutrient feed can prevent these issues from developing in the first place.
Please download this study referenced in this video and follow along: https://www.mdpi.com/2076290
0:25 Comparison Study Summary
1:17 How to test your soil
The first thing to troubleshoot issues is to test your runoff for levels outside the grow zone: https://youtu.be/FtLMn0SmQZQ
Once you confirm it is in range, then you can move on to pinpointing the deficiency,
NITROGEN (N) 2:07
Early Signs:
Yellowing of Older Leaves: The lower leaves begin to yellow while the veins remain green.
Slow Growth: The overall growth rate slows down noticeably.
Late Signs:
Widespread Yellowing: Yellowing spreads upwards from the lower leaves beginning with the fan leaves.
Leaf Drop: Affected leaves eventually droop down and may fall off prematurely due tot he plant recognizing it lack of photosynthesis.
FIXES – SYNTHETIC: https://amzn.to/4cMK6Sn ORGANIC: https://amzn.to/3L8nmR0
PHOSPHOROUS (P) 3:12
Early Signs:
Slight Rusted spots can occur, similar to calcium deficiency. Darker blotches appear, but have a brown that isnt as red or rusty as calcium.
Stunted Growth: The plant shows signs of slow growth.
Late Signs:
A purple tint may appear on stems and leaves and necrosis that look like brown smears and dead patches develop on leaves.
FIXES – SYNTHETIC: https://amzn.to/3W9DDvh ORGANIC: https://amzn.to/3XQWkoJ
POTASSIUM (K) 3:53
Early Signs:
Yellowing and Browning of Leaf Edges: Older leaves show yellowing and browning starting from the edges.
Late Signs:
Chlorosis Between Veins: Browning/rusty color between leaf veins while veins remain green. Tips of the leaves begin to curl and die and fall off. They turn crispy.
FIXES – SYNTHETIC: https://amzn.to/3zpix34 ORGANIC: https://amzn.to/4cL8KTj
CALCIUM (Ca) 4:17
Early Signs:
Distorted New Growth: New leaves may appear twisted or irregular and small rust spots appear speckled throughout the leaves.
Late Signs:
Crispy Leaf Edges: Edges of the leaves become crispy and rusty and the spots expand uniformly throughout the leaf.
FIXES – SYNTHETIC: https://amzn.to/3zu2FMV ORGANIC: https://amzn.to/3WaNtgG
MAGNESIUM (Mg) 4:52
Early Signs:
Interveinal Chlorosis: Yellowing between the veins of older leaves while veins stay green.
Late Signs:
Affected leaves may turn completely yellow and fall off and stems and petioles may turn red or purple. Striping expands eventually yellowing the whole leaf.
FIXES – SYNTHETIC & ORGANIC: https://amzn.to/4eNwCro
SULFUR (S) 5:20
Early Signs:
Overall Yellowing: Uniform yellowing throughout the whole plant. Lime green color up top that affects new growth. Unlike Nitrogen, it starts up top instead of down under.
Late Signs:
The yellowing spreads to older leaves and can appear like striping. The veins are more intense green and look like lines.
FIXES – SYNTHETIC & ORGANIC: https://amzn.to/4eNwCro
IRON (Fe) 6:00
Early Signs:
Pale New Growth: New growth appears pale or yellowish.
Late Signs:
Buds looks a little light yellow or white on the edges and develops to dark brown red.
FIXES – SYNTHETIC in VEG: https://amzn.to/4cMK6Sn SYNTHETIC in BLOOM: https://amzn.to/3W9F6Sj ORGANIC: https://amzn.to/3XOEyCA
Manganese (Mn)
Early Signs:
Not much of a difference.
Late Signs:
No noticeable difference from control.
FIXES – Same as Iron
Preventative measures is the best way to grow plants to avoid nutrient deficiencies. A balanced nutrient feed is the best solution and by using fertilizers that provide all the essential macro and micronutrients in appropriate ratios, you will fix problems before they develop.
Preventing Nutrient Deficiencies: 6:46
1. Use a well balanced feed schedule. They are available for all different mediums on hwgrow.com
2. Good Watering Routine – Prevent Over and Underfeeding: Avoid overfeeding, which can lead to nutrient lockout and water logged soil which will suffocate your roots. Understanding the wet and dry cycle is recommended, this can be done either by muscle memory or fingering the soil. Underwatering will lead to dry pockets or salt buildups in the soil, which can create abberations in soil pH and ppm, resulting in isolated deficiencies throughout you plant.
3. Maintain Proper Environment: Ensure your growing environment (temperature, humidity, and light) is optimal. Environmental stress can exacerbate nutrient deficiencies. Light burn could look like a deficiency: https://youtu.be/PwYrH3utgug
