Grow Problems
Practical problem-solving guides for the most common hydroponic issues. Symptoms, causes, and actionable fixes - no guesswork.
Problem Guide
Betalain synthesis in amaranth microgreens is temperature-dependent, not light-dependent - 24-26°C produces vivid magenta colour while 18-20°C from the same seeds produces yellow-green plants.
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Running the reservoir 20% lower between top-ups without drying roots increases glucoerucin concentration, producing the signature sharp peppery flavour arugula is prized for.
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Harvesting basil 3-4 days after bud appearance reduces linalool by up to 30% - always harvest pre-anthesis for peak essential oil content.
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Red bell peppers contain ~11x more beta-carotene and 1.5x more vitamin C than green peppers of the same variety - carotenoids only accumulate during the final ripening phase on the vine.
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Bok choy tip burn is a transpiration issue, not a calcium deficiency - adding an oscillating fan eliminates it without any nutrient adjustment.
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Broccoli microgreens contain glucoraphanin 20-50x higher than mature broccoli (Fahey, Zhang, Talalay, Johns Hopkins PNAS 1997) - this declines as true leaves emerge, making harvest timing critical.
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DWC produces tighter, more compact butter lettuce heads than NFT because constant root submersion prevents water-stress cycles - DWC consistently yields restaurant-quality closed-head form.
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Celery requires a cold vernalization period of 4-10°C for 10-14 days at weeks 6-8 to form compact ribbed stalks - without cold, it produces thin hollow petioles.
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Raising EC from 2.5 to 4.0 during final fruit swell increases Brix from ~6 to 8-9 but reduces total yield 10-15% - run EC 3.0-3.5 during final ripening to optimise for flavour.
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Clump-sown chives at 8-12 seeds per net cup produce 40-60% more total biomass over 12 weeks than single-plant culture - dense sowing is the most impactful production variable.
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Sustained temperatures above 27°C trigger cilantro bolting within 10-14 days regardless of photoperiod - temperature control is the single most important factor for extending harvest.
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Most indoor cucumbers must be parthenocarpic varieties - standard slicing cucumbers require pollination and drop all flowers indoors without insects.
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Carvone and limonene peak between 4-6 frond sets and first umbel elongation - once umbels fully open, carvone drops ~20-25%, so harvest timing is critical.
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Belgian endive chicons require complete darkness during the forcing stage - even brief light exposure triggers chlorophyll production, turning chicons green and unpalatably bitter.
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Fennel fronds contain 60-80% trans-anethole in essential oil versus 20-30% in the swollen bulb - hydroponic frond-harvest fennel is more intensely anise-flavoured than commercial bulb fennel.
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Sotolon concentration (the maple-like aroma compound) peaks at cotyledon stage on day 8-10 in fenugreek microgreens - the narrow harvest window makes germination uniformity critically important.
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Using supermarket scallion root stubs (last 3-4cm with roots) in shallow NFT produces harvestable regrowth in 7-10 days versus 3-4 weeks from seed.
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Lowering the reservoir to 12-14°C for 5-7 days increases glucosinolate and sulforaphane precursors by 15-20% - a deliberate cold treatment improves nutritional density.
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Citral degrades 30-40% within 24h at room temperature after cutting - harvesting into cold water at 4-8°C reduces citral loss to under 10% and preserves the lemon scent.
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Tip burn in hydroponic lettuce is caused by high solution temperature, not calcium deficiency - dropping the reservoir to 18-20°C resolves it without any nutrient adjustment.
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Mucilage content increases with heat in Malabar spinach - plants at 26-28°C produce measurably thicker, more gelatinous leaves than the same variety at 20-22°C, which is a valued culinary property in South Asian and African cooking.
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Radish and broccoli microgreens contain 10-40x higher vitamin C, vitamin E, and beta-carotene than their mature counterparts, but these ratios drop sharply after day 12-14 when cotyledons yellow.
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Peppermint menthol content is highest at early bloom when 10-20% of flowers are open - harvesting at peak vegetative growth yields 18-22% less menthol than early-bloom harvest.
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Mizuna germinates at reservoir temperatures as low as 10°C - cold conditions slow growth to ~60% of the rate at 18°C but concentrate mild sweetness in the leaves.
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Cooler reservoir temperatures of 15-17°C measurably increase sinigrin accumulation versus warmer water above 22°C - for spicier mustard greens, run cooler solution.
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Under blue-spectrum LEDs at 440-480nm, red oakleaf produces 25-35% more anthocyanin per gram versus warm-white LEDs - warm yellow-spectrum lights produce green-tinged plants even in red-leaf varieties.
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Greek oregano has 3-5x more carvacrol than common oregano, and intermittent pump cycles (15 min on / 45 min off) increase carvacrol further versus continuous flow.
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Stems develop better texture at EC 2.0-2.5 but leaves thicken and toughen at high EC - keeping EC 1.5-1.8 produces uniformly tender baby pak choi.
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A double-soak method - 35-40°C water for 24h, change water, soak 24h more - reduces parsley germination time from 14-21 days to 7-10 days by breaking chemical dormancy.
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Pea shoots are the only common microgreen that reliably regrows after the first cut - a second harvest of side shoots at 40-60% volume is possible 7-10 days after the first cotyledon cut, provided the first cut was made above the lowest node.
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Letting the reservoir drop 30-40% between refills during fruiting measurably increases capsaicin content - validated by New Mexico State University Chile Pepper Institute.
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Perilla flowers under any daylength shorter than 14 hours regardless of temperature - running 14-16h photoperiod delays flowering and extends the vegetative harvest window to 3-4 months.
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Pre-soaking radish microgreen seeds for 4-6 hours synchronises germination to within a 12-hour window - germination uniformity matters more than total seed count for consistent yield.
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Spacing romaine at least 20cm apart allows outer leaves to fold inward for proper head formation - crowding at 10cm produces loose flat rosettes with no heart.
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Young sage under 6 weeks is cineole-dominant with a eucalyptus aroma; plants over 10 weeks shift toward thujone (classic sage) - using cuttings from established plants starts with thujone-forward oil from day one.
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Baby-leaf sorrel harvested at 35-40 days contains ~40% less oxalic acid per gram than mature or bolted leaves - younger leaves are both better-tasting and lower in oxalate.
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At EC 2.0-2.3 spinach accumulates higher oxalates - harvest as baby leaf at 25-30 days for lower oxalate content and better flavour.
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Rebaudioside-A content peaks 2-4 weeks before the first flower opens in stevia - once flowers open, glycoside concentration drops sharply, making harvest timing more important than any nutrient adjustment.
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Day-neutral strawberries need EC 1.8-2.0 during fruiting but only EC 1.4 during vegetative establishment - running high EC from transplant delays the first fruit set.
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Placing a 500-800g weighted tray on sunflower microgreens during blackout forces cotyledons through hulls naturally, reducing manual hull-removal time by 60-70%.
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Swiss chard stem pigments are betalains, not anthocyanins - EC 1.6 produces more vivid colour than EC 2.3 because moderate nitrogen restriction intensifies betalain expression.
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True French tarragon is completely sterile - any packet labelled 'tarragon seed' is Russian tarragon with almost no flavour. French tarragon must be propagated from cuttings.
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Reservoir temperatures of 8-12°C trigger cold-acclimation converting starches to soluble sugars in tatsoi, producing distinctly sweeter, less pungent leaves versus the same variety at 18-20°C.
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English thyme averages 40-60% thymol in essential oil while lemon thyme contains only 5-10% - variety selection matters more than any growing parameter for thymol content.
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Vietnamese coriander is bolt-resistant because it evolved under consistently warm equatorial long-day conditions - it does not flower in response to long days or heat, solving the cilantro-bolting problem entirely.
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EC above 1.5 mS/cm causes leaf tip scorch and stunted growth within 7-10 days - watercress is far more salt-sensitive than most hydroponics crops and must not be run on standard lettuce recipes.
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Wheatgrass grown with zero added nutrients produces comparable chlorophyll to nutrient-grown grass - hard wheat berries have sufficient mineral stores for 7-10 days, and adding nutrients above EC 0.5 does not increase yield.
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