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How to diagnose a sick plant

Kind of a Big Deal

How to care for a sick plant.png

A plant that's drooping, turning brown or losing leaves might need some extra care. Fortunately, it's not hard to identify common problems and help your plant recover. 


Assessing your plant's growing conditions, including water intake and soil quality, is the first step in helping your plant thrive again. 


How to tell if your plant is overwatered

Overwatering is one of the most common reasons why a plant's health might start declining.


You are overwatering your plant if the soil or potting mix is always wet and is never allowed to dry out. Symptoms of overwatering include plant collapse and the onset of rotting of roots and top growth. While they need moisture to stay alive, plant roots also need to breathe. Overwatering deprives them of oxygen as the soil is poorly aerated. Excess moisture may also cause plant roots to rot. Symptoms of overwatering include plant collapseSymptoms of overwatering include plant collapse


It’s vital to ensure the soil or potting mix drains well after watering or rainfall so air can circulate, while still holding just enough moisture to sustain life. Too much moisture for too long may also cause roots to rot – and that’s often fatal.

How to care for an overwatered plant


Allow the plant to dry between waterings. Do the “finger test” to check how moist or dry the top 5-10cm is before adding more water. Stick your index finger into the soil to the second knuckle – if it comes out moist, don’t water. If the soil is dry, add some moisture.


Avoid watering on a fixed schedule, such as every second day or three times a week.  Vary your watering frequency according to the weather, the time of year, the soil or potting mix type and the plant’s size. While the label might say “water every other day”, you need to assess your particular growing conditions and adjust the recommendations to suit.


If a potted plant has been overwatered, repot it into a clean pot and fresh potting mix. Don’t keep the new mix constantly moist. Water only as required. If you’ve found the problem before it becomes terminal, the chances are your plant will recover and go on to thrive.

How to check for poor drainage in your plant


If you’re satisfied you are not watering too often but the potting mix or soil in which your plant is growing is constantly moist, drainage may be an issue.


When watering potted plants, both indoors or out, take the pots out of their saucers or decorative outer pots when you water, and check if excess moisture can flow out freely. You should not be leaving pots in water for more than a few minutes – that’s asking for trouble. Remember to empty outdoor saucers after rain.


How to improve drainage in plants


If areas of your garden don’t drain well, you may have to either install drains or grow plants in raised beds or planting mounds. Roots don’t sit in wet soil for long periods.


Affected plants, if small enough to be handled easily, can be lifted and replanted into a more suitable location, or raised in their original sites to elevate their roots above soggy soil. Backfill under and around them to create planting mounds that will allow excess moisture to drain away.


Once drainage is improved, your plants will thank you by responding well.


How to tell if your plants are not getting enough water


Plants that are not given enough water will rapidly show symptoms of drying out. The leaves may wilt or dry out or the leaf margins will turn brown. Underwatered plants may turn brownUnderwatered plants may turn brown


Generally, if caught in time, you can save affected plants. But you should remove the leaves that have died or are completely dried with secateurs or scissors, as they aren’t likely to recover.


Occasionally all the leaves die and fall off. That’s your plant’s way of trying to preserve its main stems and roots. If they are still alive, there’s hope the plant may produce new leaves and shoots.


How to care for under-watered plants


Give potted plants a thorough drenching until water drains freely from the base of the pot. Water in-ground plants until the soil is well-wetted. Follow by watering your plants as and when required. 


How to tell if your plants are underfed


Plants deprived of food can quite rapidly develop signs such as yellowing leaves or poor or stunted growth. 


Garden soils and potting mixes don’t have inexhaustible supplies of nutrients to keep plants healthy. So, the addition of natural, organic, or manmade fertilisers periodically is essential to ensure plants have sufficient food to ensure healthy growth.

How to care for underfed plants


Try a water soluble or liquid fertiliser which has nutrients that are readily absorbed to give affected plants a “quick fix”.


In the longer term, slow or controlled-release fertilisers, applied according to directions, will ensure nutrients are available when plants need them.  Yellowing of leaves may indicate a plant is underfedYellowing of leaves may indicate a plant is underfed


How to tell if your plant is over-fertilised


One sign of over-fertilising can be the buildup of a salty crust on the surface of the soil or potting mix, or under pots where excess moisture has drained out on to hard surfaces.


An oversupply of nutrients may cause soft, lanky growth that collapses quickly when the plant is stressed due to a lack of moisture or sharp temperature increases. It can also damage the fine feeding roots in the form of nitrogen burning.


How to care for over-fertilised plants


If you think your plants have been over-fertilised, flush the soil or potting mix through with fresh water, to wash the excess either out of the pot or deeper into the subsoil beneath the root zone.


Most plants recover reasonably quickly once remedial action is taken.


Ensure your plant is not growing in poor soil


Attempting to grow plants in poor soil is dooming your plants to very short lives. 


Planting direct into heavy clay or clay loam can cause major issues. Digging holes in heavy soils creates sumps, which fill with water and drown roots, especially if you backfill around new plants with a lighter soil or potting mix. Under these circumstances, most plants will not survive, so the best advice is to avoid this mistake in the first place.


When clay dries out, it cracks and can set hard, making it almost impossible for roots to thrive.


How to improve soil quality


Planting into raised beds or mounds of improved soil (plenty of compost will do the trick) will allow water to drain away from roots and give your plants a much better chance of survival. Added compost will help heavy soils to remain workable even when dry.


Light sands suffer from the opposite problems – they don’t usually retain enough moisture to sustain life. They also provide minimal anchorage for roots, leaving plants exposed to movement in strong winds. Adding plenty of organic matter in the form of composts and manures will greatly improve sandy soils, allowing them to hold moisture and develop into friable loams. 


Check for pest infestations and diseases


Insects and diseases can ravage plants very quickly if you’re not vigilant. For example, often we don’t even notice that our roses are infested with aphids until they’re present in plague proportions. By then, they might have caused irreparable damage to new shoots and flower buds. Look out for diseases like black spot on your plantsLook out for diseases like black spot on your plants


It pays to check out all your ornamental and fruiting trees and shrubs as well as vegetables and herbs. Don’t think your indoor plants are safe either – insect pests can be found on many house plants, too. Fungus gnats, for example, are a common problem for indoor plant owners. Check out the guide How to get rid of flying bugs on indoor plants for handy tips.


How to protect plants from pests and diseases


Effective control is vital if your plants are to survive. Choose natural or organic methods wherever possible and treat pests before they cause so much damage your plants are half-dead. 


While you’re checking the garden for insect pests, keep an eye out for diseases as well. Bacterial and fungal diseases can be devastating, especially bacterial blight, powdery mildew, sooty mould and black spot.


To protect plants and eradicate diseases, a regular spray program is recommended. This, in addition to putting all prunings and fallen leaves and fruits from infected plants into the household rubbish bin and not the compost, will give your plants the best chances of recovery from existing and future infections.


If a plant is dead, there’s nothing you can do to bring it back to life. However, you can investigate what went wrong to prevent the same thing happening again.


Need more help with diagnosing your sick plant?


The Bunnings Workshop community can help if you need more assistance with diagnosing and caring for your sick plant. Don’t hesitate to ask a question


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