The 15 problems that kill home crops

Tap any card to jump to its full section. Use the search to filter by symptom ("yellow leaves", "holes", "white powder", "maggots") or crop.

Fundamentals — the 20% that drives 80% of the outcome

Before any spray, any net, any bait — five things matter more than anything else in your bed. Get these right and you'll spray less often than your neighbours and still out-yield them.

1. Soil biology and organic matter

A healthy vegetable bed has 5–8% organic matter, crumbly structure you can push a finger into to the second knuckle, and visible worm activity. That means a yearly 3–5 cm top-up of compost, no rotavating when wet, and ongoing mulch. Soil biology suppresses soil-borne diseases (damping-off, nematode) far better than any fumigant available to a home gardener.

2. pH

Target pH 6.0–7.0 for most vegies. Brassicas tolerate slightly alkaline (6.5–7.5) — they also resist clubroot disease better at higher pH, so add garden lime to brassica beds. Acid-loving crops are rare in the veggie patch; don't over-correct. A $15 soil test kit pays for itself the first season.

3. Watering — deep, consistent, at soil level

Shallow, uneven watering causes more problems than any pest: blossom end rot (tomato), bolting (lettuce/coriander), split carrots, cracked tomatoes, dropped pumpkin flowers. Rule: water less often, more deeply, at soil level, in the morning. A soaker hose or drip line under mulch is the single best investment you'll make after the bed itself.

4. Mulch — the cheapest fungicide and fertiliser

A 5–8 cm layer of sugar cane, pea straw or lucerne mulch (a) stops splash-borne fungal spores (blight, early blight), (b) evens soil moisture (prevents BER), (c) feeds soil biology as it breaks down, (d) suppresses weeds. Keep it 5 cm clear of stems to avoid collar rots.

5. Variety choice and timing

Resistant varieties cost the same at the garden centre. Tomato: look for VFN (verticillium/fusarium/nematode) resistance — Grosse Lisse is prone to nematode, Rouge de Marmande and Tigerella hold up better. Cucumber/zucchini: Marketmore 76 (cucumber) and Black Jack / Golden Griller (zucchini) have the best mildew resistance in the home range. Lettuce: bolt-resistant varieties like Cos Little Gem and Oakleaf handle a hot week without flowering. Planting window matters more than most people think — see Calendar section.

The IPM pyramid — cheapest interventions first

Integrated Pest Management is the idea that chemical sprays are the last tool, not the first. The five tiers below are ordered by cost and side-effect: start at the top and only escalate when the problem survives the previous tier.

Caterpillars — the #1 home-garden pest

Four main pests across most Australian veg gardens: cabbage white butterfly (brassicas), diamondback moth (brassicas), heliothis / tomato grub (tomato, corn, beans), and loopers (leafy greens). The fix is the same for all four: Bacillus thuringiensis (Bt), spinosad, or exclusion netting.

Identification at a glance

The fix — in order of aggressiveness

1. Exclusion netting (brassicas, tomatoes). Fine mesh, 2–3 mm. The only close-to-100% method for cabbage white on brassicas. Put it on at planting, before the first butterfly arrives.
2. Hand-pick. Morning and evening walks. Crush or drop in soapy water. Will control a small home bed.
3. Bacillus thuringiensis (Bt). Sold as Dipel DF (Btk) or Xentari WG (Bt aizawai). Caterpillar-specific bacterial protein — harmless to everything else. Zero-day WHP. Spray late afternoon (UV breaks it down) at the first sign of caterpillars or eggs, reapply every 5–7 days while the adults are flying. Aizawai is stronger on diamondback and loopers; kurstaki is the general workhorse.
4. Spinosad. Sold as Success Neo or Entrust Organic. A fermentation-derived natural toxin — broader than Bt (covers thrips and fruit fly larvae too). 1-day WHP. Safe on bees once dry; still avoid spraying flowers. Rotate with Bt so you don't select for resistance.
5. Chlorantraniliprole (Coragen, Altacor). Very low toxicity to mammals/bees, highly effective. A home-garden-registered product for the bad years.

Aphids & whitefly — the sap-suckers

Both are sucking insects that feed on phloem sap, leaving sticky honeydew (sooty mould grows on it), distorted leaves, and the risk of virus transmission. Aphids hit almost every vegetable; whitefly specialises in solanaceae and cucurbits and is particularly bad under glasshouse or shadehouse conditions.

Identification

• Green peach aphid — small pear-shaped, pale green/pink, on shoot tips of tomato, capsicum, brassicas. Virus vector.
• Cabbage aphid — grey-green with white wax, colonies on brassica leaf undersides. Survives winter on seed-going brassicas and weeds.
• Cowpea aphid — shiny black, legumes.
• Silverleaf whitefly — tiny, white, powdery wings held roof-like. Adult flies up in a cloud when you disturb foliage; scale-like nymphs underneath.
• Greenhouse whitefly — similar, wings held flatter; temperate climates.

The fix

1. Blast with water. A firm hose spray dislodges small colonies and doesn't hurt a thing. Repeat every couple of days.
2. Encourage ladybirds, hoverflies, lacewings, parasitic wasps. Flowering borders and tolerating a few aphids as food is the single best long-term strategy — once predators are established, outbreaks crash quickly.
3. Horticultural oil (Eco-Oil, Trump Spray Oil, Biopest Oil). Paraffinic oil 1 % suffocates aphids and whitefly nymphs. Hits all life stages on leaves including eggs. 1-day WHP. Safe on bees once dry — avoid spraying open flowers.
4. Neem (azadirachtin). Systemic feeding deterrent and insect growth regulator. Excellent for persistent whitefly. 1-day WHP.
5. Insecticidal soap. Potassium salts of fatty acids. Works on contact only — spray direct and thorough, leaf undersides matter.
6. Registered home-garden systemics — for bad years, products like pirimicarb (Pirimor) for aphids, or flonicamid (Mainman / Chess) if available. Rotate modes of action.

Thrips

Sliver-bodied insects about 1 mm long that rasp plant cell contents and suck the sap out. Damage looks like silver-flecked leaves, distorted growing tips, and brown streaks on petals. The real problem isn't the feeding damage — it's that western flower thrips is the principal vector of tomato spotted wilt virus (TSWV), one of the most destructive viruses of tomato and capsicum in Australia.

The key species

• Western flower thrips (Frankliniella occidentalis) — hardest to control, main TSWV vector, resistant to most older chemistry.
• Onion thrips (Thrips tabaci) — onions, leeks, spring onions, brassicas.
• Tomato thrips (Frankliniella schultzei) — tomatoes, beans.

The fix

1. Reflective mulch (silver weedmat or aluminium foil) confuses incoming thrips. Very effective early in the season.
2. Blue sticky traps for monitoring and some control. Hang at crop height, check weekly.
3. Prompt removal of any TSWV-symptomatic plants (bronzy leaves, dark ringspots on fruit). There's no cure — the plant is a reservoir and must go.
4. Spinosad (Success Neo) or spinetoram (Success Ultra) — best registered home-garden actives for thrips. Rotate with other modes of action after 2–3 sprays.
5. Abamectin where registered — translaminar, hits thrips inside flower buds where contact sprays can't reach.

Mites — the hot-weather specialist

Three mites matter for home vegetable gardens, and they look and behave differently:

Two-spotted spider mite (TSSM) — Tetranychus urticae

Speckled yellow leaves, fine webbing on leaf undersides, tiny moving dots if you look with a hand lens. Worst on tomatoes, beans, cucurbits in hot dry weather. Prefers dusty dry foliage — overhead watering and mulch suppress it.

Broad mite — Polyphagotarsonemus latus

Invisible to the naked eye. Damage shows as distorted, bronzed, down-curled new growth at the tips of capsicum, chilli and beans. Often misdiagnosed as virus. Confirm by sending a sample to a diagnostic lab, or by response to sulfur treatment.

Tomato russet mite — Aculops lycopersici

Microscopic eriophyid mite. Bronzy lower stems and leaves that dry out and curl, starting at the base of the plant and moving up. Tomato-specific.

The fix

1. Water overhead occasionally — TSSM hates wet foliage. Once a week of hosing down the underside of leaves disrupts populations.
2. Wettable sulfur (Thiovit Jet, Microthiol Disperss) — cheap, effective on broad mite and tomato russet mite. Don't apply above 32 °C or within 2 weeks of horticultural oil (phytotoxic). 1–3 day WHP depending on crop.
3. Horticultural oil — effective on TSSM eggs and nymphs, 1-day WHP.
4. Abamectin or bifenazate (Acramite) — for severe TSSM outbreaks where registered.
5. Persimilis predatory mite — commercially available, excellent biological control for TSSM in warm sheltered gardens.

Slugs & snails

A single good rain can bring out enough snails to shred a bed of seedlings overnight. There's no linkable registered commercial bait in Spray Hub that's appropriate for a home garden — the old blue metaldehyde baits are dangerous to dogs, and methomyl-based baits (Flystar etc.) are S7 dangerous-poison restricted-use products and must not be used in urban or home-garden settings. The fix is exclusion plus homeowner-safe iron-based bait.

The fix — in order

1. Water in the morning, not the evening. A dry surface at dusk shuts down 80% of snail activity.
2. Hand-pick at night with a torch. 20 minutes after dark for the first week of seedling transplant clears a small bed. Drop into soapy water.
3. Beer traps. Shallow dish of cheap beer set at soil level; snails fall in and drown. Replace every few days.
4. Copper tape around raised-bed edges. Snails get a mild electric shock from the copper and won't cross. Lasts years.
5. Diatomaceous earth ring around seedlings — works only while dry.
6. Iron-EDTA (ferric EDTA) or ferric phosphate baits — sold as Multiguard Snail & Slug Killer, Eradisnail, or Blitzem Slug & Snail Pellets. Low toxicity to birds, pets, bees and kids — breaks down into iron and fertiliser. This is the home-safe bait to use. Scatter sparingly around seedling transplants and lettuce, refresh after rain.
7. Encourage predators — bluetongue lizards, frogs, ducks in larger gardens, and Indian runner ducks where council allows.

Powdery mildew — cucurbits, peas, some tomatoes

White talcum-powder patches on upper leaf surfaces of zucchini, cucumber, pumpkin, squash and peas. Spreads upward and outward, yellows leaves, and eventually kills the plant by starving it of photosynthesis. Thrives in warm days + cool humid nights — exactly Australian backyard summer conditions. Different species attack different crops (Podosphaera on cucurbits, Golovinomyces on solanaceae).

The fix — start early, escalate only if needed

1. Plant resistant varieties. Black Jack, Golden Griller (zucchini), Marketmore 76 (cucumber), Kent / Butternut (pumpkin) tolerate mildew far better than heirlooms.
2. Thin the canopy. Remove old leaves at the base to improve airflow; the fungus needs still humid air to sporulate.
3. Water at soil level in the morning. Wet leaves at nightfall feed the fungus.
4. Milk spray. 1:9 full-cream milk:water, weekly, sprayed over both leaf surfaces. Surprisingly effective as a preventative — the proteins disrupt the fungal surface.
5. Potassium bicarbonate (Eco-Fungicide, Ecocarb). Sodium bicarb (baking soda) works too but leaves salt residue. Potassium version is registered and gentler. 1-day WHP.
6. Wettable sulfur (Thiovit Jet, Microthiol Disperss). Classic preventative for cucurbit mildew. Do not apply above 32 °C (leaf burn).
7. Home-garden fungicides — myclobutanil, triforine, or propiconazole-based products for severe cases on established plants.

Tomato blight — early & late

Two different pathogens, similar-looking damage. Both kill tomato and potato. Both start low on the plant and climb. Both are triggered by humid nights and splash from wet soil.

Early blight — Alternaria solani

Brown spots with concentric rings (like a tiny target), starting on oldest lower leaves. Yellow halo around spots. Stem lesions dark and sunken. Common across all of Australia; the more usual of the two.

Late blight — Phytophthora infestans

Large greasy water-soaked patches that turn brown, with fluffy white fungal growth on the underside on humid mornings. Devastating — can kill a plant in days once established. The same pathogen that caused the Irish potato famine. Cooler, wetter conditions than early blight; worst in Tasmania, Victoria, southern NSW.

The fix

1. Mulch heavily. Stops rain splash spreading spores from soil to lower leaves — the primary infection route.
2. Stake, prune and airflow. Remove lower leaves up to the first flower truss. Train the plant on one or two leaders. Wide spacing.
3. Water at soil level, in the morning. Never wet the foliage after 4 pm.
4. Copper hydroxide (Kocide, Champ, Tribase) — preventative spray at first sign, reapply every 7–14 days. 1–7 day WHP depending on product.
5. Mancozeb (Dithane, Penncozeb) — multi-site protectant, rotate with copper. Longer WHP than copper so schedule around harvest.
6. Rotate out of tomato/potato for 2 seasons after an outbreak — the pathogen overwinters in soil and stubble.
7. Don't compost blighted material. Bag it and bin it. Burn if permitted.

Damping-off — the seedling killer

Seedlings emerge fine, then flop over at soil level and die — usually in a circular patch that expands daily. Caused by a complex of soil-borne fungi: Pythium, Rhizoctonia solani, and sometimes Fusarium. Always from wet, cold, unsterile potting mix or overcrowded trays.

The fix

1. Fresh, sterile seed-raising mix. Not reused mix from last year's trays. Not garden soil. A decent commercial seed-raising mix has low disease pressure and the right particle structure.
2. Clean trays. Wash trays and pots in 1:10 bleach solution between uses, rinse well.
3. Don't overwater. Bottom-water seedlings, let the surface dry between waterings.
4. Good airflow. Fan on a timer, or move trays outside during the day. Humid still air is where damping-off explodes.
5. Warm enough. Most veg seeds want soil 18–24 °C to germinate fast — slow germination in cold mix gives the fungi a head start. Use a heat mat in late winter / early spring.
6. Chamomile tea or cinnamon dusting as traditional preventatives (mild antifungals, surprisingly effective on small scale).
7. Biological seed treatments — Trichoderma- or Bacillus subtilis-based products (e.g. Serenade Prime) applied to the mix pre-sowing give strong preventative coverage.

Root-knot nematode

Microscopic soil-borne worms (Meloidogyne incognita, M. javanica) that invade roots and form pea-sized galls. Plants above ground look stunted, wilt in the afternoon heat despite watering, and yield poorly. Pull a sick plant up and you'll see strings of galls on the roots — that's the diagnosis.

Tomato, carrot, lettuce, cucumber, capsicum, pumpkin are highly susceptible. Corn, onion, garlic, asparagus are fairly resistant. Brassicas are moderately resistant. Once established in a bed, root-knot nematode is extremely difficult to eradicate.

The fix — cultural is the whole answer for home gardens

1. Rotate out of susceptible crops for 1–2 seasons. Plant onions, garlic, corn, or a cereal cover crop on the infected bed.
2. Biofumigant cover crops — Caliente mustard or BQ Mulch Brassica blends. Grow for 8–10 weeks, then slash and incorporate while still green. Glucosinolates in the plant tissue release isothiocyanate in soil, which suppresses nematode populations 60–80%.
3. Soil solarisation. Clear plastic laid tight over wet soil for 6 weeks in peak summer (Dec–Feb). Soil temperature reaches 50 °C+ in the top 10 cm and kills nematodes, weed seeds, pathogens.
4. Organic matter. Composts and manures build microbial competition that suppresses nematodes — a yearly 3–5 cm top-up of compost is the best long-term investment.
5. French marigold (Tagetes patula) interplanted and then worked into the soil — moderate evidence of nematode suppression. Grow a thick stand for a whole season, not a token border.
6. Resistant tomato varieties — look for the "N" letter in VFN/VFNT resistance codes. Grosse Lisse is not resistant. Many modern hybrids are.
7. Commercial nematicides (fluensulfone / Nimitz, abamectin-based Tervigo, fluopyram / Salibro) are registered in Australia but are commercial products — the home-garden answer is cultural.

Blossom end rot — it's not a disease

Black, leathery, sunken patch on the bottom (blossom end) of tomato, capsicum, zucchini, watermelon. Often shows up on the first couple of trusses and then stops if conditions are corrected. Blossom end rot is a physiological disorder — the plant fails to deliver enough calcium to the developing fruit as it sizes up. There is no pathogen. A spray won't fix it.

The actual causes

• Irregular watering — the dominant cause. Calcium moves with water flow through the plant. Dry-wet-dry cycles disrupt the supply.
• Low soil calcium — rare in Australian soils, but acidic sandy soils can be deficient.
• High nitrogen fertilisers push leafy growth faster than calcium can keep up.
• Root damage — from cultivation, nematode, or waterlogging — reduces uptake.
• High humidity in the canopy — leaves transpire less, pulling less water (and less calcium) up through the plant.

The fix

1. Mulch deeply. 5–8 cm of sugar cane or pea straw evens out soil moisture.
2. Consistent deep watering. Drip or soaker hose on a timer beats hand-watering. Water twice a week to depth rather than a daily splash.
3. Work gypsum or crushed eggshells into the bed before planting — builds a reservoir of plant-available calcium.
4. Ease off the high-N fertilisers. Once fruit starts setting, switch to a balanced or K-heavy feed.
5. Calcium foliar sprays (calcium nitrate or calcium chloride at 0.5%) — useful but only a band-aid. Fix the soil and the watering instead.
6. Remove affected fruit — the plant will redirect energy into the next truss, which should be clean if you've fixed the watering.

Fruit fly — Queensland & Mediterranean

The worst home-garden fruit pest in Australia. Females sting ripening fruit and lay eggs that hatch into maggots inside. By the time you see maggots, the damage is done — it's a prevention problem, not a treatment problem.

Queensland fruit fly (Qfly / QFF) — Bactrocera tryoni, brown body with yellow markings, present across most of eastern Australia and extending. Mediterranean fruit fly — Ceratitis capitata, confined to WA. Tomato, capsicum, stonefruit, citrus, figs and most soft fruit are all targets.

The playbook — exclusion first, bait second

1. Exclusion netting. Fine (1.6 mm) mesh over the whole plant or bed — sleeves on individual branches for stonefruit, full cages for tomatoes and capsicums. This is the only method that approaches 100% control.
2. Male lure traps — Eco-Naturalure or Cera Traps (cue-lure / Capilure based) hung from mid-spring. Use for monitoring ("first catch" = time to net) and some suppression. One trap per 25 m² of garden.
3. Protein baits — spot-spray non-crop foliage near the patch weekly from fruit-set onwards. Females need protein to mature eggs, so they get the bait before they sting the fruit.
4. Prompt fruit hygiene. Pick up every fallen fruit, including neighbours' overhanging citrus. Seal in a black plastic bag in full sun for 2 weeks to kill larvae. Do not compost.
5. Cover crops strip and bare-soil hygiene prevents pupation in the top 2–5 cm of soil.
6. Community sanitation. A single neglected stone-fruit tree next door can re-infest the whole street. Talk to neighbours — the Department of Primary Industries often has free advice packs.

Soft chemistry — the six-product home-garden toolkit

Six active ingredients cover about 90% of home-garden pest and disease problems in Australia. Keep them in a cool dark shed, rotate modes of action, and you'll only need synthetic products in rare years.

Beneficial insects — your unpaid pest-control team

Australian home gardens are full of beneficial insects if you let them establish. A diverse veggie patch with flowering borders typically hosts 5–10 major predator and parasitoid species that handle most pest outbreaks before they reach damage threshold. Reaching for broad-spectrum sprays wipes these out and creates a dependency loop.

The main beneficials you'll see

How to encourage them

1. Plant flowering borders with small, open flowers: alyssum, coriander, dill, fennel, parsley, buckwheat, phacelia.
2. Tolerate low pest levels. Predators need prey. A patch with zero aphids also has zero ladybirds.
3. Avoid broad-spectrum sprays. Pyrethroids knock out beneficials for weeks. Rotate to Bt, oil, sulfur — selective products don't disrupt the predator community.
4. Provide shelter — a small pile of logs, unkempt corners, mulch, rock piles. Beneficials need refugia.
5. Water features — a shallow dish of water attracts wasps and hoverflies in summer.

Companion planting — what actually works

Companion planting is mostly folklore, but a handful of combinations are genuinely supported by evidence. Don't rely on it as your only pest strategy — but where it does work, it's effectively free.

Evidence-based companions

• Nasturtiums as a trap crop — cabbage white butterflies will preferentially lay on nasturtiums over brassicas. Plant them around the brassica patch and pick off the caterpillar-loaded leaves weekly.
• French marigold (Tagetes patula) for nematode suppression — but only if grown as a thick stand for a whole season and then dug in. A few marigolds at bed corners won't do much.
• Alyssum between vegetables — proven predator and parasitoid habitat in Australian trials. Excellent for hoverflies and parasitic wasps.
• Dill, coriander, fennel gone to flower — the small umbel flowers attract parasitoid wasps that target caterpillar eggs (Trichogramma) and aphids (Aphidius).
• Corn + beans + pumpkin — the classic Three Sisters works because corn provides beans a climbing structure, beans fix nitrogen, and pumpkin shades the soil. Not specifically pest-reducing but a great small-plot combination.

Companions with weaker evidence

• Basil repels aphids — weak in controlled trials.
• Garlic repels everything — minimal real effect.
• Tomato and basil taste better together — a kitchen argument, not an agronomy one.

Combinations to avoid

• Don't plant tomatoes near potatoes. Same family, same diseases — early blight moves easily between them.
• Don't plant brassicas near strawberries. Strawberries harbour verticillium wilt that can jump to brassica.
• Don't put onions near peas or beans. Alliums suppress legume growth and nodulation.

Crop rotation — the four-family plan

Rotating crops by botanical family starves soil-borne pests and diseases, balances nutrient drawdown, and keeps productivity high. The simplest home-garden rotation is a four-bed, four-family cycle: every family moves one bed each season. You'll lose a lot less to blight, nematode, clubroot and soil pathogens this way than any spray can give you back.

The four families

How the rotation works

Imagine four beds, A/B/C/D. Season 1: solanaceae in A, brassicas in B, cucurbits in C, alliums+legumes in D. Season 2: everything shifts one bed — solanaceae → B, brassicas → C, cucurbits → D, alliums+legumes → A. Keep rotating each season. Each family returns to the same bed once every four seasons.

Why this order? Legumes fix nitrogen, leaving a fertile bed for the heavy-feeding solanaceae to follow. Solanaceae take N and Ca. Brassicas follow and take the remaining nutrients + add organic matter when chopped in. Cucurbits finish the cycle as heavy feeders with the bed mulched heavily between.

Garden hygiene — the uncelebrated IPM tier

Cleanliness prevents more disease in a home vegetable garden than any fungicide. The basics are tedious and nobody talks about them — but they matter more than most sprays.

End-of-season cleanup

• Pull all spent plants at season end. Bag and bin diseased material (tomato blight, brassica clubroot, cucurbit mildew).
• Don't compost diseased residue. Home compost piles rarely hit the 65 °C+ temperature needed to kill pathogens.
• Solarise suspicious material — seal in a black plastic bag in full sun for 2–4 weeks. Safe to compost afterward.
• Clear fallen fruit under any fruiting plant — fruit fly larvae pupate in the top 2–5 cm of soil.

Ongoing hygiene

• Sterilise secateurs between plants when pruning diseased material — 1:10 bleach dip or 70% isopropyl alcohol wipe.
• Clean seedling trays between uses — bleach dip + rinse.
• Manage weeds around the patch. Wild brassicas host diamondback moth and aphids. Amaranth hosts thrips.
• Sanitise bed edges — mulch keeps spore loads down, bare soil between beds splashes pathogens onto lower leaves.

Sprayer hygiene

• Triple-rinse your sprayer after every use — especially if you've sprayed herbicide in it (even glyphosate traces kill tomato seedlings).
• Ideally, keep a dedicated veg-garden sprayer that never touches herbicide.
• Empty, dry, store inverted. Perished seals are the #1 sprayer failure.

Seedlings & watering — the beginner-killers

Half of home-garden failures happen in the first three weeks, before a pest or disease is anywhere near involved. Seedling raising and watering are the two places amateurs lose whole crops and experienced gardeners hardly think about anymore.

Seedling raising

• Fresh sterile seed-raising mix. Not garden soil.
• Bottom-water. Trays sit in a shallow dish of water for 10 minutes, drain off. Surface stays drier — damping-off doesn't get a chance.
• Airflow. Small fan running during the day. Non-negotiable.
• Warmth. Heat mat for warm-season seeds (tomato, capsicum, cucurbits). Most spring failures in temperate areas are just cold soil.
• Light from day one. Leggy stretched seedlings = not enough light, not too much water.
• Harden off for 5–7 days before transplant — increasing outdoor time each day.

Watering rules

1. Deep, less often. 2–3 times a week to 20 cm depth, not a shallow daily sprinkle.
2. At soil level. Drip, soaker hose, or careful hand-watering at the base. Never overhead after 4 pm.
3. In the morning. Leaves dry by midday. Evening watering feeds fungi and slugs.
4. Mulch to hold it. 5–8 cm mulch doubles the interval between waterings and evens soil moisture (prevents BER, fruit cracking, bolting).
5. Feel the soil, don't watch the surface. The top may look dry while 10 cm down it's saturated. Stick a finger in to the second knuckle — dry? water. Damp? wait.

3-Season Australian vegetable calendar

Most of temperate and subtropical Australia runs three planting windows: warm season (after last frost), cool season (autumn–early spring), and a short transition window in late summer for autumn brassicas. Tropical north runs wet-season and dry-season with totally different crop choices — this calendar is aimed at the southern half of the country.

Warm-season plant-out

Cool-season plant-out

Month-by-month problem calendar

• Spring (Sep–Nov): aphids explode on fresh brassicas, cabbage white arrives, damping-off hits seedlings in cool soil. Set out exclusion nets, start Dipel program, keep seedling trays warm.
• Early summer (Dec): first heliothis on tomato flowers, thrips on capsicum, QFF first catches. Net the stone-fruit, set up fruit-fly lures, scout twice a week.
• Mid summer (Jan–Feb): peak mite, peak mildew, peak QFF, peak blossom end rot. Mulch heavy, water deep, rotate fungicides. Solarise any bed headed out of production.
• Late summer (Feb–Mar): late blight risk rises with humid nights, autumn aphids return on fresh brassicas. Last warm-season plant-out, first cool-season plant-out.
• Autumn (Mar–May): aphids on brassicas, slugs/snails after rain, damping-off in cooler seedling trays. Set out copper-tape borders, iron-EDTA bait, fresh seed-raising mix.
• Winter (Jun–Aug): quieter pest pressure but disease-refugee time. Plan rotation, order seed, build compost, solarise troublesome beds.

Registered products — linked to Spray Hub

Every product below is in the Spray Hub product database and registered for home-garden or small-plot use in Australia. Click through to the label, active ingredient, rates and withholding period. Always read the label.

Resistance management & safety

Why resistance happens in a home garden

You wouldn't think a 4 m² tomato bed could breed resistance, but continuous-use pressure on a confined population does exactly that. Heliothis, diamondback moth, two-spotted mite, powdery mildew and late blight are all well-documented resistant to multiple chemistries. The fix is the same at home as on commercial scale: rotate modes of action.

Rotation rules

• Never spray the same active more than 2–3 times in a row. Rotate to a different IRAC / FRAC group.
• Caterpillars: Bt → spinosad → chlorantraniliprole → Bt. Three groups, never the same twice.
• Mildew: sulfur → bicarb → copper → sulfur. Multi-site products (M1, M2, M3) are low resistance risk — lean on these.
• Aphids: oil → neem → pirimicarb → soap. Rotate modes of action and lean on predators.

Safety — personal, pets, pollinators

• PPE: even for soft chemistry, wear enclosed shoes, long sleeves, gloves, eye protection. Wash hands and clothes after spraying.
• Bees: don't spray open flowers. Spray early morning or late evening when bees aren't foraging. Oil and neem are bee-safe once dry but not when wet.
• Pets: keep dogs and cats out of sprayed beds until dry. Never use metaldehyde snail baits. Never use methomyl products (S7 dangerous poison — restricted use, commercial only, not for home or urban use).
• Kids: lockable shed for all chemistry. Keep in original labelled containers. Never decant.
• Withholding periods: printed on every label. For soft chemistry most WHPs are 0–3 days. Check before every spray.
• Disposal: triple-rinse empty containers, puncture, and dispose through council chemical collection. Don't tip unused product down the drain.

Records

Even in a home garden, keep a simple log: date, what you sprayed, which bed, the weather. Two seasons of records transform your decision-making — you'll see which products actually worked on your mildew, which year the nematode took hold, and whether that new fruit-fly trap is earning its keep.

Frequently asked questions