Battling heat and root problems

Spring and summer are great times to practice hydroponics outdoors without expensive lighting systems, but indoors or out, we’re all going to be battling the heat and the stresses it can cause to our plants. Decaying, dying, and dead root material can be the bane of many hydroponic (and some soil) growers – especially during the warm summer months!

As gardeners, we must remember that as the temperature in the root zone increases, the rate of respiration of the root tissue also increases. Believe it or not, for every 18 degree F rise in temperature, the root respiration rate doubles.

This means that the higher the temperature, the more oxygen is required by the plant.

We must also remember that as the temperature of the nutrient solution increases, the ability of that solution to “hold” dissolved oxygen decreases. So, as the temperature from night to day goes from 68 to 86 degrees F, the plant has doubled its need for dissolved oxygen while the nutrient solution the roots are bathed in has lost over 25% of its oxygen holding capacity.

Common consequences of inadequate oxygen supply to the root zone include:

Wilting of the plant during the warmest part of the day – Less dissolved oxygen means water is less accessible to the roots, which not only dehydrates, but can also lead to a buildup of toxins. At this point, the plant cannot absorb water or minerals enough to support itself under these stressful conditions.

Decreased yield – at the same time your plant is wilting it is also reducing its rates of photosynthesis and carbohydrate transfer, which will ultimately affect your yield.

Root problems – if this oxygen starvation continues, mineral deficiencies appear, roots begin to die back, and the plant becomes stunted. Ultimately, these anaerobic conditions cause the plant to produce a stress hormone (ethylene), which causes the collapse of the root cells.

Enter Pythium (AKA Root Rot).  Most growers don’t realize that Pythium is an “opportunist” fungus, which takes advantage of plants that have been stressed (particularly by high water temperatures and oxygen starvation in the root zone).  Pythium is present worldwide in soil, air, vegetation, and hydroponic systems, making it extremely unlikely that a grower will be able to eliminate the disease.  This doesn’t mean we can’t fight it though!

 

At Fifth Season, in addition to recommending a growing medium with higher air porosity during warmer months, we advise employing the following weapons to battle root decay:

• Most importantly- take control of your root zone environment by using proper (and clean) air stones and water chillers if needed.
• Hydrogen Peroxide 29% – when used appropriately can be a sterilizer and oxygen source, with or without plants in the system.
• Cannazym – A blend of 12 different enzymes that break down dead root material and convert it into a mixture of glucose and minerals (which is actually edible to the plant!).  Cannazym also contains easily absorbable vitamins and desert plant extracts that not only heal the root zone but promote new growth.
• Hygrozyme- An OMRI certified blend of enzymes and amino acids.
• Flora Shield – an all purpose anti-microbial solution made of a unique combination of compounds that will thoroughly rinse systems and plants during all phases of life. Safe to use on plants of all ages and non toxic to fish, Flora Shield can protect your plant from 97% of bacteria and fungi without using harsh or toxic chemicals.
• Beneficial Fungi and Bacteria – Our stores offer many varieties for all different purposes. These little helpers naturally help keep the root zone clean and healthy, but aren’t always recommended in hydroponic gardening. Come visit one of our store locations to talk about whether these are right for you.
• Physan 20- A general disinfectant, fungicide, algaecide (it is toxic to fish), and virucide used to control a wide variety of pathogens on hard surfaces and plants.