Indoor enclosed spaces like grow rooms would seem to provide ideal protection to plants against pests and parasites that can cause much harm to crops grown conventionally. It would seem reasonable to believe that since plants are grown in a comparatively sanitized environment without soil, a pest attack scenario would be unlikely, even remote. But pests wouldn’t be pests if they were so easy to shake off; so whether it is a hydoponics grow room or a green house, these tiny and not so tiny marauders have to be kept away. Fortunately, there are several ways growers can go about protecting their precious plants against these invaders.



Anything and everything can serve to introduce pests into the grow room, even humans are no exception. Once pests gain a foothold in the grow room, they multiply manifold, rapidly consuming plants and playing havoc with your indoor garden. The first step to regain control over your grow room is to identify the culprit. Once this is done a number of “soft" and “hard" control options are available to target the offending intruders.

Control Strategies

When only a few plants are infested growers can dip a small brush in insecticide or methylated spirits and apply directly onto plants to eradicate pests such as mealy bug or scale. This method is often very effective in protecting valuable indoor plants where spraying may not be acceptable. Moths can be dealt with using pheromone traps that help eliminate adult moths before they can lay eggs. Even hand-held vacuum cleaners have been reported to be effective against flying pests, particularly whiteflies.

Repellent Sprays, Powders and Formulations

Garlic sprays and hot pepper wax barrier are often used by growers in pest control. While these are mostly available off the shelf at any gardening supplies store, many growers prefer to make their own versions. However, the results seem to be mostly inconsistent, with some growers claiming excellent results while others reporting less than satisfactory outcomes. Some growers report that pests thrive on foliage treated with repellents.

Soaps and Oil Sprays

Soaps and oils have also proved effective in pest control. They work by blocking the pest’s breathing pores, thus smothering the pest. They also prevent some pests like mites from moving around and breeding. Soaps and oils are fairly safe. They can be easily stored and conveniently applied. Regular application over long periods, however, leads to buildup of oil/soap on hydroponic system components. This can be washed off from time to time.

Certain mineral compounds and diatomaceous earth work as natural or non-chemical insecticides. Diatomaceous earth has desiccant action on the insects. It also forms an abrasive layer slowing crawling insects like slugs and worms. It forms a dusty residue on hydroponic fruits or vegetables must be washed off.

Biological Formulations

A number of bio-pesticides are available in the market today. Perhaps, the most widely used of these is Bt spray, which is obtained from the bacterium Bacillus thuringinesis. Bt spray is applied to plants which is then absorbed by caterpillars as they feed. A bacterial toxin is formed in the digestive system of the caterpillar, which causes it to stop feeding. Dehydration sets in and the pest dies in a few days. Different strains of Bt have been developed for use against specific insects. It is important to use the right strain of Bt meant for a specific pest as the wrong strain will not work.

Some other products have been formulated from fungal pathogens of various insects. These work best under the right conditions. If the conditions, for example, humidity is not high enough, the controls are not effective.

Botanical Formulations

The two most common botanical extracts used for pest control in hydroponics are a pyrethrum, derived from a daisy (Chrysantehmum Cinaeraefolium) and neem oil derived from the seed kernels of the Indian neem tree (Azadiracta indica).

Pyrethrum is often combined with other compounds to enhance effectiveness; it can be used to control a wide range of pests. Neem oil or various extracts of neem are available as oil, solvent extract and as a ground product. Neem is an insect growth regulator, meaning, it stops the insect's life cycle. Neem is effective on particularly difficult pests like whitefly; it is also a good general purpose spray option for small-scale growers.

Growers often erroneously assume that since they are made with plant extracts soft pesticides are safer than chemical pesticides. The truth is that these can be more toxic to humans than some synthetic pesticides. Handling these products requires the same care and application as synthetic biological controls.