Wilting even though the root zone is moist, not recovering overnight
Wilts under lights, partly recovers at night at first, then stops recovering; often with yellowing..
- Also called
- wilting but soil is wet
- drooping won't recover
- plant wilting in hydro
- wilting with wet roots
Likely causes, most likely first
Ranked for this sign on its own. Your stage, medium and readings change the order, so run the checker for your plant.
PossibleRoot rot (Pythium)
Fix: Act now. Fix conditions first: solution at 18-21 °C (65-70 °F), strong aeration (6-8+ mg/L DO), no overwatering. Change the reservoir, trim dead roots with clean scissors, clean and disinfect the system. Then either re-establish beneficial microbes (Bacillus, Trichoderma; house-preferred) or commit fully to a sterile regime (e.g. dosed hypochlorous acid or peroxide). Isolate affected plants on recirculating systems.
Recovery: New white root tips within 3-7 days and wilting stops; brown roots don't recover.
How to confirm it
- Look at the roots. Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Smell test of roots, medium and reservoir. Smell the roots, the bottom of the root ball, the drain water or the reservoir up close. Healthy roots smell earthy or of nothing. A sour, rotten, swampy or sewage smell means anaerobic conditions and rot. In hydro, a slimy feel on the reservoir walls or tubing adds to the case.
- Measure reservoir and root-zone temperature at the end of the light period. Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.
- Dissolved oxygen check. Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.
- Send a sample to a plant diagnostic lab. For rots, wilts, leaf spots and viruses you can't separate by eye, send a fresh sample (whole plant with roots or a wilting branch with healthy and diseased tissue) in a sealed bag to a university or commercial plant diagnostic clinic. Results in days to 2 weeks.
PossibleLow dissolved oxygen in the root zone
Fix: Restore oxygen: clean or replace air stones, size the air pump for at least ~1 L/min per 4 L, keep a 2-5 cm air gap under net pots once roots reach the water, cool the solution to 18-22 °C (64-72 °F). Aim for 6-8+ mg/L DO.
Recovery: Fresh white root tips within 3-5 days; wilting stops.
How to confirm it
- Dissolved oxygen check. Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.
- Measure reservoir and root-zone temperature at the end of the light period. Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.
- Look at the roots. Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Check pumps, timers, nozzles and drippers. Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.
PossibleReservoir or root zone too warm
Fix: Keep solution at 18-22 °C (64-72 °F): insulate and shade the reservoir, move it off the warm floor or away from the light, use a chiller or frozen water bottles in an emergency, avoid submersible pumps that add heat, cool the room.
Recovery: Solution holds below 22 °C through the light period; new white roots in 3-5 days.
How to confirm it
- Measure reservoir and root-zone temperature at the end of the light period. Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.
- Dissolved oxygen check. Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.
Less likelyFusarium wilt or crown rot
Fix: No cure once infected: remove the plant with its medium in a bag, sanitise pots, trays and water lines, and use clean clones and new media. Reduce root stress (overwatering, heat, salts) on the rest.
Recovery: No further wilting plants over the next 2-3 weeks.
How to confirm it
- Cut a wilting stem lengthwise. On a wilting or dying branch, scrape the lower stem and cut it lengthwise with a clean blade. Brown streaks in the water-conducting tissue point to vascular wilt (Fusarium). A dark, sunken crown points to crown rot. Disinfect the blade afterwards.
- Send a sample to a plant diagnostic lab. For rots, wilts, leaf spots and viruses you can't separate by eye, send a fresh sample (whole plant with roots or a wilting branch with healthy and diseased tissue) in a sealed bag to a university or commercial plant diagnostic clinic. Results in days to 2 weeks.
- Look at the roots. Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
Less likelyPump, timer, air or emitter failure in a hydro, aero or drip system
Fix: Restore flow or air immediately: check power, timer, float switches, filters and nozzles. Mist exposed roots by hand or lower plants into solution while you fix it. In HPA and NFT, fit an alarm and a backup pump; roots die fast when misting or flow stops.
Recovery: Plants regain turgor within hours if roots were not dead; brown, collapsed roots mean rot risk next.
How to confirm it
- Check pumps, timers, nozzles and drippers. Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.
Less likelyRoot aphids
Fix: Confirm on the roots. Apply soil-dwelling biologicals (Beauveria bassiana drenches, Stratiolaelaps scimitus, Steinernema or Heterorhabditis nematodes), sanitise, and leave a plant-free gap between cycles; dispose of infested media.
Recovery: No live aphids on root checks after 2-3 weeks; growth resumes.
How to confirm it
- Root-ball and drainage-hole insect check. Tip the plant out and inspect the outer roots, pot bottom and drainage holes with a 10x loupe. Root aphids are small, pear-shaped and wingless, often with white waxy flecks; check several plants, and the drain trays, since colonies hide at the pot edge.
- Sticky cards for 1-2 weeks. Hang yellow cards at canopy height and lay one flat on the medium surface; add blue cards for thrips. Count catches every 3-4 days. Rising counts of small dark flies at the medium mean fungus gnats; slender insects mean thrips; white wedge-shaped fliers mean whiteflies; winged aphids mean a colony nearby.
Less likelyBoron deficiency
Fix: Rule out broad mites first. Supply about 0.2-0.5 mg/L B (boric acid ~1.1-2.9 mg/L, or a complete micro mix). The gap between enough and too much is narrow: never add B 'just in case' on top of a complete feed.
Recovery: New shoots grow normally from the tip or from side buds within 10-14 days.
How to confirm it
- Magnifier check of leaf undersides and new growth. Use a 10-20x loupe for spider mites, thrips, aphids and whiteflies, and a 30-60x lens or clip-on phone macro for broad and russet mites. Check the undersides of 10 affected leaves across several plants and the newest shoot tips, in white light. Look for moving dots, eggs, shed skins, webbing, slender insects with black specks, and glassy specks on new growth.
- Look at the roots. Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Leaf tissue analysis. Send 20-30 most-recently-matured leaves (no petioles) from affected plants, and separately from healthy ones, to an agricultural lab. Compare with cannabis and hemp sufficiency ranges (for example N 3.3-4.8%, Mg 0.40-0.81%, K 1.8-2.9% dry weight in recent mature leaves). Results take 1-2 weeks; use it to confirm a chronic problem, not an emergency.
Look for
Wilted plant next to a damp pot or full reservoir; photograph the roots..
The full guide: Why is my cannabis drooping or wilting? The master decision tree
Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.
