Keep your plants healthy and prevent pests and diseases

Prevent Pests And Diseases

Keep your plants healthy and prevent pests and diseases

The idiom goes ‘prevention is better than cure’ and is touted by professionals across the board. With all things health related, prevention outweighs cure, as by the time a cure is needed, damage has already happened. So, when it comes to gardening, how can you prevent pests and diseases from causing damage to your plants?

Preventing Pests And Diseases

There are multiple factors which can cause plant pests and diseases or give them ideal conditions in which to thrive. Basic prevention practises apply to any form of gardening, whether outdoors, indoors, hydroponics, windowsills etc…


It’s the most basic thing about growing plants, but I don’t just mean watering, but humidity as well. Seedlings need a higher level of humidity to stop moisture loss before roots develop. Mature plants on the other hand, require a lower level of humidity to allow for transpiration. Too much humidity leads to mould and damping off. Alternatively, too little humidity can lead to leaf damage and proliferation of spider mites. Remember, ideal soil composition is 50% solids (minerals, rocks + organic matter), 25% air and 25% water. Too much water leads to root rot and too little to dehydration. Both of which weaken the plant and allow it to be attacked by pests and diseases. Also, high temperatures combined with water reservoirs/tanks can lead to Pythium. Control measures vary depending on your growing method, but a simple temperature/humidity monitor can help.


Movement of air is important when it comes to indoor/protected plants. The air movement can help balance the humidity and stop build-up of damp. Care should be taken with outdoor plants that are bushy with dense foliage. Restricted air flow can lead to mould and other diseases such as fungal scab in apples. Regular pruning to allow air movement is recommended.


Restriction of light can lead to proliferation of mould and fungus. It also reduces photosynthesis in affected leaves, leading to necrosis (death of the leaf on a cellular level). Regular pruning can help. Also, be aware of the number of light hours that the plant needs at various growth stages and the amount it’s getting.


The basic rules of hygiene that apply to humans also apply to plants. It’s easy to think that with them growing in dirt, using dirty secateurs/snips is ok. However, clean hygienic practises will help prevent pests and diseases.

Any time you’re going to cut a plant, whether this is removing leaves, harvesting fruit or pruning, a clean sharp implement should be used. The cleanliness reduces the chance of infection in the ‘wound’ by bacteria or fungi. Using a sharp blade reduces chances of tearing the ‘wound’ which reduces healing time and enlarges the infectable surface area.

The removal of dead leaves as well as any diseased or damaged parts of the plant should be standard practise (known as the three D’s). However, be careful not to break out the chainsaw every time a leaf becomes slightly yellow. Simply wait till over 50% of the leaf appears irreversibly damaged/dead before removing. With diseases however, once identified, remove all infected material as soon as possible. The infected material should then be burnt, or hot composted to stop any spread. This will reduce the chance for the disease to spread.


As a producer of nutrients, it’d seem bias that I’d say the right plant food can prevent pests and diseases. However, there is truth (and a little advertising!) in this. The greatest prevention of pests and diseases is having strong and healthy plants.

Healthy plants are more able to use their own natural defences to resist pests and diseases. They are also likely to survive for longer compared to a weaker/sicker plants. So, using balanced nutrients with a full range of secondary and micro-nutrients to maintain healthy plant growth is recommended.

As well as general health there are a few nutrients that can help a plant to build stronger defences. Silicon can be added to all feeding regimens to increase strength throughout the plant. Not only will this reduce the chances of stems snapping under the weight of a heavy fruit such as tomatoes, but it makes it a lot harder for sap-sucking insects (such as aphids) to penetrate the plant. Furthermore, the plants become more resistant to extreme of temperature and drought.


In nature, plants often form symbiotic relationships with other organisms. A symbiotic relationship is where two organisms benefit from living together for nutrition or protection. Plant roots can form a symbiotic relationship with beneficial fungi, such as Mycorrhiza, protecting them from soil-borne pathogens. The fungi cover the roots, protecting them whilst taking carbohydrates from the root for nourishment. Plant Magic Granules are a blend of Mycorrhiza, Trichoderma and bio-stimulants that will help protect your plants root system.

Friendly bacteria and other microbes can protect the surface parts of the plant from fungal spores and pathogens using biofilms. These can both combat and impede botrytis (black mould) and leaf spot fungus. Essence from Plant Magic has a consortium of beneficial microbes to protect a range of plant types and growing environments. It also contains a microbial feedstock that will allow it to thrive straight away.

Ultimately, all these preventative measures are subject to observation and care of your plants. Regular inspection of your plants is key when looking for deficiencies, pests, diseases and checking temperatures, humidity and ventilation. The sooner a problem is identified, the better the chance there is of stopping pests and diseases from causing damage.

Plant Magic offers a range of products which can help you prevent pest and diseases, and some products which can improve lead deficiencies.