The way you choose to react to your crop failing is crucial. With some blood, sweat, and a few tears, you will be able to overcome most of your serious issues causing crop failure. Try to remain calm at all times. Make yourself a body of knowledge logbook to note the problems you encountered and what worked to fix them. Be prepared to work through it as it is common to have problems, especially with stressed plant tissue and bug or mold infestations.
Growing Mediums and Overwatering
Overwatering is a common problem for many beginners as plants can become starved of oxygen and the growing process comes to a complete standstill. Pot size can be one reason for overwatering issues. One example is a 60-liter pot can stay wet for a long time, causing issues like root rot that can lead to crop failure.
When using a grow medium such as rockwool, overwatering can occur, especially in the early stages of vegetative growth. I recommend using aquarium bubblers and long air stones to encourage the rockwool to dry out. Coco and perlite mixes are also susceptible to overwatering and care must be taken when using these media. I find a 1:1 mixture works very well. If overwatering occurs, do not increase temperatures in your growroom to dry things out as this can lead to all sorts of nasty complications in the root zone.
Patience is often the key to overwatering issues to keep your plants happy while the medium is drying. Try misting the foliage with half-strength food daily until your growing medium is back on track. Expanded clay balls are hard to overwater, making it a great growing medium for beginners.
Read More: 5 Growing Mediums and Their Benefits
Overfertilizing is another issue that leads you directly to crop failure. Less is sometimes best, though be careful and experiment depending on the genetics of your crop. Overfeeding will lead to visible signs of leaves being burned from toxicity. Investing in a multi EC/pH monitor is a great way to stay away from this type of crop failure, especially when running recirculating systems.
When plants are young, less is best. Regularly calibrate your EC/pH monitor and have a twinkle around and determine for yourself whether you have excellent growth rates and healthy plants with less recommended strength. When EC toxicity occurs, try flushing salts from your growing medium with warm, distilled water. Warm water helps to flush salt out better than cold, especially in soil mediums. Under-fertilizing can diminish final harvests. I suggest keeping a feeding schedule on a whiteboard to maintain vigorous growth and maximum yield.
Incorrect pH will cause nutrient lockout, which will cause your plants growth to be stunted and perform very poorly. Make sure you calibrate your pH monitor and EC monitors regularly. Some plant food manufacturers will buffer the pH for you so every time you mix up you may notice pH is always fine.
The environment you create in your growroom is essential. The humidity should be in between 50-65% in vegetative stages and just under 50% in flowering stages. This will help prevent any mold from growing, keeping in mind fresh air needs to be pumped in regularly.
Fluctuations in temperature greater than 10 degrees are not recommended. I find 28˚C when the lights are on and 18˚C when off works well. Too far outside these temperatures will stress or kill your plants, so be sure to employ heaters or air conditioners to keep growroom temperatures moderate. Some crops can survive high temperatures for a brief period indoors while others thrive in high humidity.
Some parts of the world warm up to 50˚C during the day and drop below freezing by the night so consider this when growing equatorial genetics. In this case, less food and more water. Winter grows are always easier in maintaining correct temperatures. The quality of the finished product is also excellent due to cold air getting onto to the fruit in the finishing week.
Airflow and Humidity
Keep oscillating fans on all the times to strengthen plants, simulate the wind, and especially when in final crucial stages of the fruiting process, good airflow will not allow mold spores to settle and flourish inside and around thick fruit. Investing in a humidity and temperature controller also helps keep your grow room mold-free.
Remove all dead foliage from the growroom floor and from inside the canopy of plants. A vacuum cleaner helps up best. Dead plant tissues alongside humidity and darkness is a haven for mold. Always avoid pinching and bending stems as once the plant tissue is damaged it can create an entry point for diseases. Tying plants to achieve an even canopy should be done with correct ties from gardening center.
Mold growing on fruit can be killed instantly with a hand-held blow torch. If you have everything running smoothly you will find that the leaves that fall into the canopy and get stuck will dry out to a crisp instead of falling onto a piece of fruit growing in final stages causing potential nightmares.
Mechanical Failure and PLCs
Mechanical failure is common. If the irrigation system fails, this leads to roots drying up and plants eventually dying. If the thermostat controller fails, the growroom will become very hot and plants will stress out and die if not rectified. Sometimes you may encounter roots growing into your irrigation pipe creating blockages that can lead to watering issues. Programmable logical controllers (PLC) are an excellent addition to your growroom if you want to get technical and constantly monitor every aspect of your operation.
These days the plants can tell you exactly which spectrum they require at any particular moment through sophisticated software/hardware. PLCs can be programmed to ring your mobile and alert you of any faults, and you can also receive a video call so that you can see exactly what’s wrong. Depending on your budget, remotely controlling certain aspects of your set-up can also be done with an app on your smart phone.
Pruning and Tying Down
Keep your pruning tools clean and sterile, isopropyl alcohol is useful for this, otherwise use heat to sterilize tools. When pruning, avoid taking any more than 15% of the total plant as this creates stress. If needed you may need to thin out your canopy to let some airflow in depending on genetics. Also, use pruning techniques that create an even canopy, pinch the apical growth point out with a pair of tweezers at the 12th set of branches making the smallest incision as possible. This will help you shape your hedge to achieve heavier yields.
The leaves are very important, especially the shade leaves, so don’t remove too many of these big ones as they play an important role in the balance and cycle of the plant.
Read More: Influencing Auxins Through Pruning
When everything else is running smoothly, biological problems appear just to keep you interested and learning! Insects! Especially in winter when bugs are supposed to be overwintering, some cheeky, tiny insects find their way into your growroom to experience an endless summer ravaging your healthy crop. Detect them early; use a microscope or magnifying glass if needed to keep a close eye on things.
Biological control is advisable at any sign of a thrip infestation as these will lead to crop failure. These little sap-sucking bugs are very nasty and microscopic. Add six stages of metamorphous to complete the life cycle of a thrip, and you have one nasty little villain you want nowhere near your growroom.
Homemade soil mixtures with loam soil from your garden will bring all sorts of bugs, good and bad, into your growroom. I would recommend only trying this with small plants in five- to10-liter pots with a 1:1 perlite to soil ratio to assist in wet/dry periods. Do your research!
Stress on your crop due to many different factors will slow growth significantly. Two weeks to get back on track isn’t unusual once you’ve solved your problem. Be patient. Taking photos and visiting your local hydroponics store is also another good way to determine the issues you are facing if you are struggling to determine the fault. Research, research, research.
Always check expiry dates on all nutrients, beneficial bacteria and other additives, as expired products can fry your entire crop.
A fire caused by electrical faults can destroy an entire crop in minutes, not to mention other valuable items. You can never be too careful. Keeping a fire extinguisher nearby or installing a sprinkler system is mandatory.
When things go wrong, the main aim is to never give up and try to be as proactive as you can afford to be. Remember the issues you dealt with successfully and make sure these don't re-occur.
Again, recording your efforts in a garden log is helpful. You will learn much from the way you respond to crop failure, and don’t be hard on yourself. Being a successful indoor gardener is something that is not easy; it’s an art form and will come to you with some time, effort and patience.