The Interior Plant Environment

Page 1 The Interior Plant Environment Google Slides Presentation By: Crystal Price Page 2 Temperature ➔ Low 4 - 18 C ➔ Medium 13 - 21 C ➔ High 16 - 30 C These are guidelines for the amount of heat a plant requires to develop normally. This assumes that all other environmental factors are also in the appropriate range. Page 3 Light The most important limiting factor in plant growth! Light influences the plant's environment and its biochemical & physiological processes in many ways: ● Photosynthesis ○ Low light can inhibit growth even if all other necessities of growth are present ● Chlorophyll synthesis ○ Green pigment in plants ● Temperature ○ Light warms the surface of plants Page 4 Light is emitted from its sources in various wavelengths! Color Spectrum ★ Light energy or wavelengths fall within 400 - 700 nanometers (NM) (PAR), which are important for plant growth. ★ Visible light (the light we see) falls within PAR ○ However PAR extends out past the visible range into the Far Red,Infrared and the Ultraviolet Page 6 When it comes to light in plant growth, there are three basic characteristics to look for. 1. Quantity - Intensity or brightness 1. Duration - Day length 1. Quality - Color A plant's response to all of these varies by the species. Balancing plant light requirements is an important factor. Page 7 Light Intensity - Quantity Quantity of light refers to: ● The amount of light energy the plant receives ● Brightness of light is measured in ○ Foot candles (FC) or lumens Ex. On a sunny day in the greenhouse a crop could receive 10,000 fc of light. On a cloudy day especially during winter, light levels are much lower. When light intensity levels are low supplemental light is required. Page 8 Plants with low light requirements can be grown in areas with no natural light, but with the use of a combination of cool white and warm fluorescent tubes. ➔ New tubes can provide up to 1000 f.c. when the plant is 6-12 “ away from the source ◆ Lights are left on for 14 - 18 hrs per day Page 9 There are two basic ways to look at light quantity. 1. Illumination or Photometric a. A measurement of visible light level, as seen by the human eye (Foot candles or lux/lumens) 2. Irradiation or Radiometric a. Looks at all energy from a light source i. Measurement is focused on the wavelength range of 400 - 700 nm *This is the region that corresponds with PAR Page 10 The following rating is given as a guide to the light intensity by a particular plant in footcandles. Low 25-75 f.c. (300-2400 f.c./day) Medium 75 - 150 f.c. (2400-6000 f.c./day) High 150-1000 f.c. (6000+ f.c./day) Page 11 ★ Too much light can be as damaging so can too little light. ★ Plants exposed to very high light are susceptible to scalding and will not photosynthesize Minimum: ● At this light intensity a plant will not be able to produce energy to maintain itself over the long run ○ Overtime it will have to be replaced Recommended: ● The level at which the plant will be able to replace old leaves as they die Ideal: ● This intensity will provide the plant with enough light to replace old leaves and put on new growth. Page 12 In the interior plantscape, the intensity of light is dependent on a number of factors. 1. The source of light a. How far the plant is from the light source 2. Obstructions a. Blinds, curtains, posts 3. Light reflected from surfaces a. Texture of the surface b. Color of the surface i. White reflects 90% ii. Grey or beige 50% iii. Mirrors 80-90% iv. Drapes 35% Page 13 Symptoms of incorrect light intensity depends on the species light requirements. Symptoms Intensity Too high Intensity Too Low Leaves defoliation, slow or rapid x x new leaves small x x all leaves yellow and dropping x x leaf blade longer than normal x leaf thin x petiole longer than normal x petiole shorter than normal x loss of variegation x reduced holes in split leaf plants x leaves very thick x leaves may scorch/sunscald edge/center x new leaves bleached, curled won’t return to normal x shade loving plants develop chlorosis, become very brittle, thick, chlorophyll damaged x Stems new growth leggy x few lateral branches x elongated stems and wide internodes x dead stem tissue x leaves close and stems thicker than normal x Page 14 Duration refers to the total measure of accumulated light over one day and is also known as photoperiod. Houseplant Lighting Explained Further Growers will supplement or cut off light to control maturation ● This is called photoperiod control Photoperiod response ● Changes naturally with the season ○ Has a definite effect on plant growth ● The longer the photoperiod the more time there is to photosynthesize ○ Therefore more energy for growth to take place ○ Plants make their greatest amount of energy with long days & short nights Page 15 When photoperiod is reduced or lengthened it sends signals to plants to respond in different ways. It may induce: ● Dormancy ● Abscission of leaves ● Setting of buds There are two main responses: 1. Short Day Response ○ Plants will only go into reproductive phase under a shorter day or long night situation ○ They will flower when they receive less than 12 hrs of bright light (absolutely all light must be blocked out) 2. Long Day response ○ Will only go into the a reproductive phase under a long day or short night situation ■ They will only flower when they recieve more than 12 hrs of light Page 16 Visible light is made up of several wavelengths, each individual wavelength possessing a certain color. Quality: ● When you look at visible light from the sun, it appears white, but if you look at it through a prism, the light is broken up into its separate wavelengths, which you can see as different colors. Page 17 The majority of light for plant growth is in the visible light spectrum The measurement and comparison of this color spectra is known a “quality”. ★ While all wavelengths within PAR are required, some wavelengths are more important than others. Page 18 While plants are sensitive to one or more wavelengths, the human eye is sensitive to others! Page 19 Foot-Candles & Lux Lighting Terms Foot-candles and lux measure the same thing—the amount of visible light that falls on a surface. The difference is that the foot-candle uses the Imperial standard measuring system (feet, pounds, etc.), while the lux uses the metric system (meters, grams, etc.). A single foot-candle is equivalent to the amount of light that falls on a surface that is one foot away from a single candle, and a lux is the amount of light that falls on a surface one meter away from a candle. For conversion, 1 foot- candle = 10.764 lux. Page 20 Additional Tips for Indoor Lighting 1. Know your plants light requirements. a. Low, medium, high 2. Purchase a light meter (inexpensive). a. Amazon Dr. Meter 3. Read this article for additional ways to measure light for plants. a. Greenery: Unlimited b. This will ensure the area is receiving the required light levels. NOTE: If you’re used to working with lux or are using an instrument that only measures lux, please note there’s a direct conversion between the two units of measurement. 1 lux = .0929 foot-candle So you can simply multiply your total lux by .0929 to get your foot candle measurement. Page 21 Water is essential for plants growth ● In the interior plantscape temperature is fairly consistent ○ Therefore the rate of transpiration is lower ○ Water requirements will be lower ○ Time of year will affect water uptake Page 22 There is no standard rules that will tell you how often interior plants will need to be watered. How often you have to water is affected by a number of factors: 1. The physical environment ● light intensity and duration ● air and soil temperature ● relative humidity (RH) ● drafts 2. Age of plant 3. Type of plant 4. Size of plant 5. Size and composition of the container 6. Water holding capacity of the growing medium 7. Soluble salt content of the growing medium 8. Plant growth activity (time of year) 9. Condition of the root system Page 23 Deciding when it is time to water! It is important not to overwater as this reduces the oxygen available to the roots and increases the chance of disease. ● On the other hand never let the media dry out. ○ A plant should never be allowed to wilt ● A plant may wilt for other reasons: ○ Overwatering, overfetilizing & excess salts can also cause wilt ○ Wilting can happen from low RH, bright light & high temps ○ Root rot Before you water, make sure watering is required! Best way to do this is to touch the soil & look at the medium & know how much the plant needs. Page 24 Watering guidelines depends on the species. Very moist - do not let the media go dry between waterings. Moderately moist – allow the media to go slightly dry between waterings ( the amount of drying will depend on the species). Moderately Dry – allow the upper level of the media to dry between waterings Dry – allow the media to dry almost entirely between watering Page 25 Moisture Meters can be added to HELP with determining watering needs. ● Moisture meters should not be used alone. Page 26 How much to water? ● When watering plants in containers with drainage holes ○ Enough water should be used to thoroughly wet the entire growing medium ○ Allow for some drainage out the bottom of the container ● Shallow watering will encourage roots to grow only in the top portion of the container ○ Small amounts of water will result in build up of salts in the medium. Page 27 Watering Methods Leach irrigation: ● Involves watering from the surface allowing the water to percolate down through the medium. ● Medium should be thoroughly wetted each watering ○ About 10% of the water should wash through the root zone into the drainage area ○ Ensures soluble salts are kept low enough to maintain long term root health ● Some issues to consider: ○ Compacted and settled soil ■ Leach irrigation may result in overwatering ■ Root-bound plants have the tendency to be overwatered or underwatered Never allow the plant to sit in the water that has leached through the medium during watering. Page 28 Subirrigation: ● Water seeps into the media through capillary action from reservoir at base of the planter or planting bed ○ Allows wicks or other means to allow movement of water upward ● Requires less day to day attention and provide stable soil moisture if managed properly ● Monitor soil salts closely ● Use good quality water ● Replace compacted soils immediately ● Use mulches to reduce surface evaporation Page 30 Water Temperatures ★ Ideally water temperature should be at least equal to the leaf temperature. ○ 5 C warmer will help speed up water absorption ★ Cold water cools soil temperature & slow water & nutrient absorption ○ Also known to damage roots & leaves ★ Philodendrons and Sansiveras are examples of sensitive plants to temperature. Page 31 Water Quality Soluble salts: ● The amount of soluble salts in the water is an important consideration with evaluating quality ○ Water with low soluble salts can be used without any special practices ○ Water with medium salt content is usable only if special practices are followed ■ provide adequate drainage in the media ■ do not allow the medium to become more than moderately dry ■ do a soil test regularly ■ leach periodically to remove the excess salts that will accumulate in the medium Page 32 Water Quality Issues: Hard water: ● High in calcium & magnesium salts ○ Gradually increases pH of medium ○ If is sits on the leaves ■ White unsightly residue when it evaporates ■ Residue is difficult to remove without a cleaning agent Soft water: ○ High sodium water destroys soil structure ○ Increases soil salt content ○ Becomes toxic to plants Page 33 When fluoride damage is suspected, maintain higher soil moisture with aerated water or distilled water to dilute fluoride concentrations. Chlorine and fluoride: ★ Municipal levels of chlorine are not likely to cause toxicity ○ High levels (5-10 ppm) may cause minor chlorosis in some species ★ Fluoride may be injurious to some species ○ Cause brown, necrotic spots or lesions especially in older leaves To minimize fluoride injury: ○ Keep pH 6 - 6.5 ○ Allow irrigation water to sit open at room temp. for 24 hrs ○ Avoid superphosphates or fluoride containing amendments ■ Perlite in the medium Page 34 Relative Humidity RH is the actual humidity of the air. ➢ Warmer the air temp ○ The more water it can hold ■ RH decreases ○ In Alberta in the winter RH can be as low as 15% ○ Some plants require 60% or more ➢ Most indoor plants are produced in an environment with much more moisture in the air than is found in the average home or building. Page 35 Ways to Increase Relative Humidity Ways to increase Relative Humidity ● Build a humidifier in with the heating system ● Install a misting system* ● Group plants so moisture from transpiration creates a microclimate ● Use a tray filled with gravel or sand, sit plants on top and fill with water ● Use a terrarium ● Place plants in areas where there is naturally more humidity ie: bathroom ★ Need to mist regularly to keep humidity up. ○ May cause disease problems ○ Increase air circulation to help leaf surface dry quickly ○ Mist in the mornings Page 37 Media Whether you buy premixed or mix your own the ultimate goal is the media fits the required criteria! Indoor plant soil requires 4 properties: 1. Support - physically support the plants 2. Water holding capacity 3. Air spaces 4. Nutrient holding capacity 5. Stability ○ They will be in the mix for a long time Different potting mixes on the market including specialty mixes like: ● Cactus mix & Azalea mix ● But often are peat based media enhanced with ○ Perlite, vermiculite, sand, composts, fertilizers or water crystals