Top 10 Troubles in the Beginner’s Growroom

By Lynette Morgan
Published: January 1, 2016 | Last updated: April 26, 2021 11:44:00
Key Takeaways

Establishing a hydroponic garden for the first time can be an exciting experience with all the new toys, tools, meters and monitors to play with. While your leafy oasis benefits from the latest and greatest in hydroponic technology, it still takes a little skill and attention to turn out perfect plants month after month. Here are 10 of the most common newbie mistakes. Are you guilty of any of these?

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Many of the most common things that go wrong in a novice gardener’s indoor garden lack straightforward visual indicators like seeing pests or molds on leaves. Pests and diseases are often absent from a new operation, at least for a short while, as there is no old crop residue from previous plants grown in the same space.


Most new growers have fully researched their new crops and have been advised by experts and retailers in the industry about installing lighting, temperature controls and nutrients, so the first mistakes often come as a complete surprise. Many of the following 10 common mistakes in the growroom can be prevented with a little diligence during the initial stages of plant growth.

Infrequent Checks

Being complacent because the garden has the latest gadgets is one of the most common issues growers face in the early stages. Many beginners are weekend growers who are busy during the week and devote their weekends to their gardens, but a lot can go wrong if plants and systems are not thoroughly checked every day, even when all aspects of the growroom are fully automated.


Many major issues arise because some aspect of the system broke down, blocked up, failed or simply didn’t work as it was meant to and the problem wasn’t discovered until it was too late.

Some examples of what can go wrong in both commercial and hobby hydroponic operations include irrigation blockages; nutrient and acid dosers getting stuck open; pump or light timers failing or not being set correctly; CO2 units delivering toxic levels of CO2; pH meters and monitors that are not calibrated weekly so they start to drift; and water top-up valves failing.

Growers should check daily, or even twice a day, if possible, that all their equipment is working as it should, including manual checks of temperature, substrate moisture and reservoir water levels, as well as EC and pH levels.


Growers should also take a long, hard look at plants for any initial signs of trouble. Once the little problems are ironed out, and the workings of all the new equipment become familiar, these issues are far less common.

Overdoing It

Killing plants with kindness is one of the most common mistakes made by beginners. Sometimes more is not necessarily better, particularly when it comes to plant growth. Many problems that show up in the growroom arise from inexperience with crop requirements, particularly in hydroponic systems, which are somewhat different than growing outdoors in soil. It can take some time to learn how often to irrigate and fertilize, to go carefully with the additives and supplements, and to always follow manufacturers’ instructions and recommendations.


Overwatering can rapidly become lethal in some systems, particularly those that use a grow media with a high water-holding capacity, or when conditions are cooler and with crops that prefer a drier root system. Overwatering is the main cause of outbreaks of pythium and other root rot pathogens, but it’s an underlying cause that is not recognized by beginners, who blame the disease rather than the root saturation that started it all.

Excessive nutrients, high EC and salt buildup on the surfaces of grow media are also common beginner problems. While under-fertilization causes weak, spindly, pale growth, over-fertilization is just as damaging, so paying attention to EC levels is important. New growers should frequently replace recirculating nutrient solutions to correct any imbalances, and check the EC of drainage/leachate in non-recirculating systems regularly to make sure salts are not building up around the root zone.

Not Knowing When and Where to Measure

Knowing when and where to measure and monitor is just as important as the process itself. A temperature sensor may display the air temperature in one area of the indoor garden, but it may not detect high-temperature leaf damage. Infrared thermometers can be used to non-invasively measure leaf temperature, which can be considerably different than the temperature in a shaded part of the canopy. Leaf damage caused by lights positioned too close to plants can be prevented by monitoring the temperature of the leaf surfaces in several different positions under the lights. CO2 should only be measured during the day when plants are photosynthesizing. Light levels should be measured both at the top of the leaf surface and inside the canopy, where most of the leaves sit, as this will indicate if plant density is too high, restricting light penetration down into the lower levels of the crop.

Overcrowding Plants

It may seem obvious that only a certain number of plants can be grown in a given space, but overcrowding is an extremely common mistake. When plants are young, the area may seem sparse with a lot of empty space, but once plants reach maturity, each one will still need sufficient light and airflow to maintain growth and productivity.

Spacing plants properly can take some experience, so beginners should start off slow, use the recommended plant spacings and be vigilant about pruning, training and removing excess plants if overcrowding becomes obvious. It requires more skill to manage factors like light penetration into the canopy, airflow and prevention of diseases in high-density gardens.

Sudden Changes

Plants need time to adjust and sudden changes can cause problems. Two of the most common examples of this are changes to the EC and changes to light levels. If the EC is rapidly increased or decreased, it causes changes in the osmotic pressure around the root system.

A rapid drop in EC or a flush with fresh water can cause plants to take up water quickly, which may split cells and fruit. A rapid increase in EC can prevent roots from being able to take up enough nutrient solution to maintain plant turgor and wilting may occur.

If EC changes are made, they must be made slowly—over a few days—so plants can adjust to the new levels. Sudden increases in light levels on plants that were previously grown in the shade can cause leaf bleaching and burning, so gradual increases are recommended. This process is sometimes called hardening-off plants.

Neglecting Fresh Air Needs

Plants need fresh air for respiration, photosynthesis and humidity control. With some species, a good breeze will help keep them strong and compact and prevent listing. Air replacement and ventilation is commonly overlooked by beginners, yet it contributes highly to productivity, yields, plant health and the prevention of certain physiological disorders.

Sufficient air should be moving through the plants so the foliage can be seen moving in the breeze. This removes the stale air or boundary layer from the leaf surface, delivering fresh supplies of CO2 for photosynthesis and removing the humid, saturated air created by transpiration. Enclosed growrooms that have little ventilation to retain heat may deplete essential CO2 levels within an hour or two.

Not Providing Enough Light

Insufficient lighting and overplanting both reduce the amount of PAR (photosynthetically active radiation) each plant receives. Beginner growers should seek advice from lighting manufacturers to ensure they are providing the correct light intensity for their plants. They should also continue to measure and monitor PAR throughout the operation of the indoor garden.

Insufficient lighting is a common problem in new hydroponic set-ups, as lamps are expensive pieces of equipment and newer technologies such as LEDs are not always easy to understand and compare. New growers often base their opinions about light levels on how bright things seem to the human eye, which is an inaccurate way of gauging PAR.

Light meters are a valuable tool in any indoor garden and knowing exactly how much PAR to provide goes a long way towards troubleshooting common lighting issues.

Failing to Identify the Enemy Early

Sooner or later, most beginner growers will encounter a pest or disease problem, and troubleshooting these issues early is the best form of control. There is no one single way of preventing attacks by pests and diseases, and healthy plants can be affected, along with weaker plants.

Running high humidity levels (more than 70%) puts plants at risk for certain diseases, and low humidity is a major risk factor for mites, which rapidly breed in warm, dry conditions. Troubleshooting involves careful inspection of plants. Use a hand magnifier and learn the visible signs and symptoms of the most common pests and pathogens for each crop.

Not Using Quality Ingredients

Using high-quality nutrients specific to the grow medium and stage of growth, the correct type of acid, and strong, disease-free transplants are all part of ensuring a new system is successful.

Beginners should know about their water supply—details like whether it is hard or soft, what water treatment chemicals it contains, and its pH and sodium levels, are all factors that are easier to troubleshoot before plant growth issues start to occur. Using nutrient products recommended by other growers can prevent some common mistakes with beginner systems.

Not Doing Your Research

One of the best forms of troubleshooting is a little education before anything untoward occurs. Checking out photos of common pests and diseases, both on the tops of plants and on the roots, as well as physiological and nutrient disorders specific to the species of plants being grown, can help prevent many initial problems from becoming serious issues.

Taking note of the recommended environmental parameters such as light, temperature, humidity and CO2 levels, and comparing those to what is happening in the garden, will keep things ticking along nicely before the need to troubleshoot arises.


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Written by Lynette Morgan | Author, Partner at SUNTEC International Hydroponic Consultants

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Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University, New Zealand. A partner with SUNTEC International Hydroponic Consultants, Lynette is involved in remote and on-site consultancy services for new and existing commercial greenhouse growers worldwide as well as research trials and product development for manufacturers of hydroponic products. Lynette has authored five hydroponic technical books and is working on her sixth.

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