Greenhouse farming can be done in all climate zones including hot, cold, moderate, and tropical climates. One of the greatest advantages of greenhouses is the ability to achieve optimal growing conditions. This is as opposed to open fields, where climate control is not possible. For example, when it is too cold to grow tomatoes outdoors, they can be grown in warmer conditions in a greenhouse. And in the hot summers, when it is too hot or dry to grow outside, humidity can be added to grow in the greenhouse. The ability to control the growing conditions also reduces the risks associated with sudden changes in weather conditions, creating added security and predictability to the growers.
But, like in any controlled environment, potential problem areas exist in greenhouses that must be monitored and proactively addressed. Losing control of your environment can lead to cultivation headaches ranging from poor airflow to extreme temperatures, as well as opportunities for diseases, such as waterborne viruses like Pythium.
Here are a couple of problems farmers face in greenhouse farming.
Problems associated with greenhouse farming
- Likely the biggest issue in greenhouse management is pests. The ideal conditions for growing plants are often also ideal for populations of pests such as aphids and thrips. Both not only damage plants, but also act as vectors for disease. Aphids attract ant populations as well. Aphids and thrips aren’t the only pests attracted to the comfortable conditions inside a greenhouse. Other pests likely to be found include fungus gnats, shore flies, bloodworms, whiteflies, leaf miners, mealybugs, and mites. Creepy crawlers like cutworms, army worms, loopers and other caterpillars may make their way into the greenhouse, as may snails and slugs.
- Pests are not the only unwelcome guests to plague the greenhouse. Diseases are another greenhouse plant problem. Diseases such as botrytis, rusts, root rots and powdery mildew are fairly common in the greenhouse. All are fungal diseases caused by spores that are moved about by air currents or water droplets
- Clogged air filtration systems are a common greenhouse issue that can be remedied by changing the air filters on a regular basis.
- Temperature swings can be a major issue in the greenhouse. The structure may become too hot due to inordinately high temps or wildfires. Overly hot greenhouses may use shade cloth or a greenhouse whitewash to control both ambient and radiant temps. Greenhouses that tend to stay too cold can be managed with thorough, routine inspections and maintenance of existing heating systems.
- Issues with irrigation and/or fertigation systems are another headache for the greenhouse operator. Timely repair or replacement of defective equipment is the key to managing this greenhouse issue. All systems should be flushed and drippers cleaned regularly with a hydrogen peroxide and water solution to minimize clogging. Mold issues are yet another issue when it comes to greenhouses.
- Mold encourages pests and diseases, sometimes to the extent that an entire system needs to be decontaminated. Ideally, you should disinfect systems, including lines and water tanks, after each harvest using a water and hydrogen peroxide mix.
- The accumulation of fertilizer salts in fertigation lines can result in a spike in nutrient solution electrical conductivity. Regularly inspect and clean fertigation lines and injectors to prevent under or over fertilization.
Some of the solutions to undertake in greenhouse farming
Typically, greenhouses are not sealed environments (such as hybrid facilities with glass roofs), but rather forced air/positive pressure environments. This means that they should be equipped with air filtration and sterilization capabilities on both the intake air and the exhausted air. The intake air is filtered and sterilized for pest and disease prevention. A proper ventilation system also allows a grower to control vapor pressure deficit (VPD) to some degree.
With such extreme environmental temperatures, one possible recourse that doesn’t require increasing air conditioning capacity is to use either shade cloth or a greenhouse whitewash to control excessively hot environmental conditions, both ambient temperatures as well as radiant temperature.
In colder climates, a heating system is a must. An inefficient heating system can be expensive at best and dangerous at worst. If growers are experiencing cold spots in the greenhouse or lower temperatures overall, and inspections for leaks and gaps where cold air could be infiltrating have been conducted, the heating system might be at fault.
Watering and fertigation systems
After harvest and in between crop cycles is the perfect time to troubleshoot and repair/replace any and all worn out, broken or defective irrigation or fertigation equipment. Measure the flow rate to determine whether a fertigation system is functioning properly. Ideally, growers will have a baseline that was first measured after the system was installed against which to compare. Diminished flow could be a sign of a clogged filter, dripper, or dose meters. Wilting plants are an obvious sign of a potential irrigation problem. For automated irrigation systems, however, a computer should tell growers there’s a problem before it is even noticeable in the plants.
Constant mold and pests
Besides the overall function of the watering/fertigation system, close attention to disinfection is a major priority. Pythium and other vectors for disease can be transmitted by contaminated irrigation equipment and/or contaminated water. If growers are experiencing continued Pythium problems over multiple crop cycles, consider decontaminating the entire watering system, including lines and the water tank (if a water tank is used). Again, in ideal situations, this should be done after each harvest. If the watering system is sanitized but issues persist, it might be time to deep clean the greenhouse.
Crops drying out
If crops seem constantly dehydrated, inspect all related electronic controls responsible for watering, timing and cycles for clogs or mechanical failures to prevent possible over/under watering or not watering on time.
What do farmers need to know
There are some natural remedies when it comes to pest control inside the greenhouse. Spraying herbicides, even organic herbicides, is generally not a good long-term solution, particularly in small greenhouses. With limited ventilation, sprays tend to accumulate in the soil at levels that are toxic for plants. The following natural remedies can be used to control pests and fungi:
Steeped and cooled chamomile tea is a natural anti-fungal that works great to prevent damping off and is safe on young plants. Nettle tea helps prevent mildew on leaves and mold in the soil but is best for mature plants. Rhubarb tea mixed with castile soap helps control aphid, mite and whitefly populations on non-edible plants.
Citrus peels boiled in water can be sprayed onto white flies to reduce their population.
Lady bugs are available for purchase and mail order and are a great natural predator for aphids.
For more information on greenhouse farming and installation, contact Mazero Agrifood on 0729777711.