3. Control The Environment
Temperature and humidity must be kept within proper parameters at all times. A good rule of thumb is to never exceed 85 degrees or drop below 60. Relative humidity (RH) should be kept around 40-50 percent, although this varies according to your plants’ growth stage—vegetating plants can handle a bit higher (60-70 percent), and RH should come down to 30-40 as plants approach harvest.
Keep in mind, heat, and moisture at canopy level can be quite different than the readings elsewhere in your room. Monitor these factors at the leaf surface to keep your plants happy and productive. Use air conditioning, heaters, humidifiers or de-humidifiers accordingly.
4. Dial-In pH
pH (potential Hydrogen) is the measurement of the acidity or alkalinity of your soil and nutrient solution on a scale of 0.1 – 14, with one being the most acidic, seven being neutral and 14 the most alkaline. Hydroponically-grown plants should be kept between 5.5 and 6.2, and soil-grown plants should be between 6.0 and 6.8.
When pH fluctuates outside these acceptable levels, certain nutrients become unavailable to the roots, even when they are present. This is often misdiagnosed as a deficiency, compounding the problem and causing great distress to your plants. Use a pH monitor and pH “Up” or “Down” as necessary.