Cannabis plant problems
Find what is wrong with your plant by what you see, then fix it. Not sure? Send a photo to the Grow Doctor.
Nutrients
- Stikstoftekort: Lower, older leaves turn pale green, then evenly yellow from the tip inwards
- Te veel stikstof (de klauw): Leaves are very dark green, almost shiny
- Fosfaattekort: Dark, dull or bluish green leaves with brown to purple patches, often on older leaves
- Kaliumtekort: Leaf edges and tips turn yellow, then brown and crispy, starting on older leaves
- Calciumtekort: Small brown spots with sharp edges on new and middle leaves
- Magnesiumtekort: Yellowing between the veins of older and middle leaves while the veins stay green
- IJzertekort: The newest leaves turn pale yellow while their veins stay green
- Zwaveltekort: New leaves turn evenly lime green or yellow, veins included
- Zinktekort: New leaves are small, narrow and wrinkled
- Mangaantekort: Yellowing between veins on new and middle leaves with a thin green border along the veins
- Borontekort: Growing tips die back or grow hollow and twisted
- Voedingsverbranding: Leaf tips turn yellow, then brown and crispy, a few millimetres in
- pH-blokkade: Several deficiencies at once: yellowing, spots and burnt edges together
Water and roots
- Overbewatering: The whole plant droops with leaves that feel firm and swollen, not limp
- Onderbewatering: Leaves hang limp and soft, like they have no strength
- Wortelrot: The plant wilts even when the medium is wet
Light, heat and air
- Lichtverbranding en lichtverbleking: The top leaves closest to the light turn yellow or white while their veins stay green
- Hitte stress: Leaves fold upwards along the middle like a taco
- Koude stress: Leaves and stems turn purple (beyond what the strain normally shows)
- Lucht te droog: Leaves curl and feel thin and dry
- Lucht te vochtig: Water drops on leaves or walls in the morning
- Vossenstaart-bloemen: Small spires of new calyxes stack on top of the buds
- Slappe, uitgerekte zaailingen: Long thin stems that fall over
- Windverbranding: Leaves near a fan are clawed, dry or torn
- Hermofrodieten en bananen: Yellow banana shaped growths (nanners) appear between the buds
Pests
- Spintmijt: Tiny white or yellow dots on the top of leaves
- Thrips: Silvery, shiny scratches on leaves
- Schimmelmuggen: Small black flies around the soil surface
- Bladluizen: Clusters of small soft green, black or white insects under leaves and on new shoots
- Witte vlieg: Small white flying insects that rise when you touch the plant
- Rupsen en knopwormen: Holes eaten in leaves
- Rustmijt en brede mijt: Leaves curl up at the edges and turn shiny, glossy or bronze
- Wortelluis: Plants stall and yellow without a clear reason
Diseases
- Meeldauw: White, flour like patches on the top of leaves
- Schimmelrot (botrytis): A bud has brown, dry or slimy parts inside
- Septoriabladvlekkenziekte: Round yellow spots on lower leaves that turn brown with a yellow halo
- Wortelrot (damping off): A seedling suddenly falls over
- Fusarium- verwelking: Leaves yellow and wilt on one side or one branch first
- Hop latent viroid (HLVd): Plants grow smaller than expected and stay stunted
Handling and timing
- Een mannelijke plant: Small round balls on short stems where branches meet the main stem
- Verplantingschok: The plant droops for a day or two after repotting
- Zaden kiemen niet: No taproot after 5 to 7 days
- Achtergebleven autoflower: An autoflower starts flowering while still very small
- Te vroeg of te laat geoogst: Early: most trichomes are still clear, pistils mostly white, effect thin and racy