Garden Problems: Working Out What Is Wrong Before You Buy Anything
The instinct when a plant looks unwell is to buy a treatment. Most of the time the cause is water, light or soil, and a treatment for something else makes no difference at all.
Check the environment first
Four causes account for most of what goes wrong:
- Water — too much or too little. Both produce wilting, which is why they get confused. Feel the soil rather than looking at it. Dry and wilting means underwatered; wet and wilting means the roots are drowning and rotting.
- Light. Leggy, stretched growth reaching in one direction means not enough. Bleached or scorched patches mean too much, too suddenly.
- Nutrients. Uniform yellowing of older leaves usually means the plant is hungry, particularly in containers where the compost is exhausted.
- Roots with nowhere to go. A pot-bound plant stops growing, dries out constantly and stops responding to feeding.
Work through those before assuming an infestation.
When it is actually a pest
Look at the plant properly, including the undersides of leaves, where most things live.
- Clusters of small insects on new growth — aphids. Often controllable by squashing them or a strong jet of water. They also attract predators that solve the problem for you.
- Fine webbing and stippled leaves — spider mites, usually in hot dry conditions. Raising humidity helps.
- Ragged holes overnight — slugs and snails, if there are slime trails.
- Neat semi-circular notches from leaf edges — leaf-cutter bees. Harmless. Leave them.
- White powdery coating — mildew, a fungal issue driven by poor airflow rather than a pest.
Identifying before treating matters, because a product for one problem does nothing for another and some are harmful to the insects you want.
Do the least first
The order that causes least collateral damage:
- Physical removal — picking off, hosing down, pruning out the affected part.
- Barriers — netting, collars, copper tape, fleece.
- Improving conditions — spacing for airflow, watering at the base rather than the leaves, feeding appropriately.
- Encouraging predators — ladybirds, hoverflies, birds. Plants that attract them do more over a season than spraying.
- Targeted treatment, only when the above has not worked and the problem is genuinely damaging.
Broad-spectrum treatments kill pollinators and predators alongside the pest, which frequently makes the following season worse.
If you do treat
Read the label for what it is approved for and whether it is safe on edible crops. Follow the dilution exactly — stronger is not more effective and can damage the plant. Apply in the evening or early morning, never in strong sun, and never on open flowers where pollinators are active.
Check what is legal and approved where you live. Product availability and approvals differ significantly between countries and change over time.
Before you order
Identify the problem before buying a product for it. Check the label covers your specific plant and pest, and whether it is approved for edibles if you are growing food. Check the shelf life, since garden chemicals bought for one incident usually expire before the next. And consider whether a barrier or better airflow would solve it without any product at all.