Why Are My Grape Vine Leaves Turning Brown?

Most browning in grape leaves traces back to water stress, heat/sun scorch, nutrient imbalance, or disease. Pin down the pattern first—edges, patches, spots, or whole leaves—then fix the cause.

Crisp brown edges (leaf scorch): Hot, dry winds or underwatering; also salt/fertiliser burn on dry roots.
Tan patches on sun side (sunburn): Sudden exposure after heavy pruning/leafing; common in heatwaves.
Brown tips + yellowing between veins: Magnesium or potassium deficiency—more common in sandy/coastal soils.
Brown spots with yellow halo: Fungal leaf spots (e.g., anthracnose); coalescing into ragged holes.
Brown felt/bronze stippling under leaves: Mites (hot, dry summers); leaves look “dusty” or bronzed.
Whole leaf browns, stays limp: Waterlogging/root rot or severe heat collapse.

Australia note: inland heat and coastal winds intensify scorch; humid coasts raise fungal risk. Diagnose by pattern + recent weather + watering habits.

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Step-by-step fixes

Reset watering: Soak the root zone deeply, then let top 2–4 cm dry before the next irrigation. Avoid daily “sips.” Add 5–8 cm mulch (sugarcane/straw) to stabilise moisture and roots.
Shield from harsh sun (temporarily): If sunburn is active, use 30–40% shade cloth on the afternoon (west) side for 7–10 days. Rebuild gentle leaf cover around clusters on the morning-sun side to avoid future scald.
Feed correctly (don’t spike N):
- Canopy rebuild (spring): Apply balanced, water-soluble feed every 3–4 weeks:
  CompleteGrow NPK 20-20-20.
- Fruiting (summer–autumn): Prioritise potassium & Ca/Mg every 4 weeks for sweetness and leaf resilience:
  CompleteGrow NPK 4-18-38 + CaMg. Pots: half-strength every 2–3 weeks, flush monthly to prevent salt buildup.
- Always water → feed → light water-in. Never fertilise dry soil (prevents edge burn).
Prune & train for airflow: Tie shoots to wires, remove tangled/over-shaded laterals so leaves dry fast after dew/rain (reduces fungal browning).
Fungal spots: Remove and bin worst leaves; keep the canopy airy. Avoid overhead watering; irrigate mornings. (For persistent outbreaks, follow a labelled fungicide program.)
Mites/bronzing: Hose undersides of leaves, boost humidity slightly with mulch, and keep plants unstressed; use a labelled miticide only if needed.
Drainage problems: If soil is heavy or sour-smelling, fork gently to aerate, raise the bed, add compost/coarse material, and water less often but deeper.

What to remove, what to keep

Remove fully crisp, necrotic leaves and any that are disease-speckled.
Keep partially green leaves—they still photosynthesise and help recovery.

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Prevention checklist (Aussie conditions)

Water rhythm: Deep, infrequent soaks matched to weather; mulch to buffer heat and reduce salt stress.
Sun management: Leaf around clusters on the morning side; avoid sudden full exposure after heavy pruning.
Nutrients by season: Spring = balanced (20-20-20); Summer/fruiting = K + Ca/Mg (4-18-38). Skip high-N late season.
pH & soil: Aim ~6.0–7.0. In sandy soils, feed a bit more often at lower strength; in clay, improve drainage to prevent root stress browning.
Airflow: Train shoots; don’t let the canopy become a wet, shaded “tent.”

FAQs: Brown Grape Leaves

Only the edges are brown—what’s the likely cause? Leaf scorch from heat/wind or fertiliser applied to dry roots. Rehydrate deeply, mulch, and only feed on moist soil.

Brown patches after heavy leaf removal? Sunburn. Restore gentle morning-side leaf cover and give temporary west-side shade during heat spikes.

Browning with yellow between veins—nutrients? Often magnesium or potassium shortfall. Keep a steady program: NPK 20-20-20 in spring, then 4-18-38 + CaMg in summer.

Whole leaf browns even when I water? Check drainage—waterlogged roots mimic drought at the leaf. Improve aeration, raise beds, and water less frequently but more deeply.

Bottom line: match water to weather, protect from harsh sun, and feed by season. Most browning reverses once stress is removed and the vine gets a balanced spring feed followed by potassium-rich fruiting support.