Whew it's hot. Really hot. I was a hot sweaty mess, sitting down planting some cuttings when I looked around and noticed my landscape plants were as hot as I was.
June 1st marks the beginning of our rainy season here in Northeast Florida, and for me, marks when I can turn off my irrigation. Also a side note: by this time of year, all fertilizing for the summer should have already been done. Any fertilizer you add after this point is subject to leach away directly into our waterways and aquifers, a leading cause for non-source point pollution. We can see an incredible 8" of rain in a single month during our rainy season.
Rain gauge - available at most hardware stores. Add mosquito dunks to kill larvae
As a general rule of thumb, established landscape plants and lawns require 1" of water per week to remain healthy. The best way to measure if your plants are getting enough water by rainfall is with a rain gauge (don't forget the mosquito dunks!). But the waters get a little muddy when you add in factors like drought, high heat, windy conditions, newly planted plants and winter dormancy. Let's go over some watering principles.
When is the best time to water? Anytime your plants are showing signs of extreme stress. Seriously. There is no right or wrong answer here since severe water loss will cause plants' cell walls to collapse which leads to cell death. But there are some things to keep in mind when you're planning your watering schedule.
Early mornings: Ideally, the best time to water your landscape is early in the morning just as the sun is rising. This gives water enough time to permeate the soil and thus plants enough time to absorb as much water as possible before the heat of the day.
Midday: There are times plants are screaming for water midday and you should give it to them; especially in the case of potted plants or newly planted plants trying to become established. Watering midday comes with negativity, but if a plant is extremely stressed then the benefits outweigh the risks of cell damage.
Drawbacks with watering midday:
Higher evaporation rates: water may evaporate before it reaches the plants roots therefore, water is being wasted.
When water droplets land on the leaves in the height of the day, it can evaporate quickly leaving behind concentrated mineral deposits on leaves, blocking photosynthesis and can cause leaf burn.
Late Afternoon/Night: There's times when watering in late afternoons are necessary. If you come across a time where your plant needs a drink in the afternoon, try to water between 4:00 and 6:00 PM, before the sun goes down. This gives the leaves time to dry because many diseases thrive on wet foliage that the sun usually burns off. The later you water the higher the risks of disease and fungus to spread. Whereas too much evaporation midday is bad, no evaporation at night is even worse. Watering at night on a regular basis is a sure way to induce root rot, powdery mildew, anthracnose etc. Afterall, damp moist areas are a breeding ground for many fungal and bacterial diseases. Try to limit water splashing on foliage and don't make watering at night a routine.
In Nassau County, we've had 4.6" of rain in the month of June. (http://webapub.sjrwmd.com/agws10/hydroreport/) So according to those totals, my landscape should not need any more irrigation this week. However, there are some signs that it is in need of a good drink.
Know the signs. It is typical for plants to wilt during the heat of the middle of the day. I expect to see my sweet potato vines, pumpkins and cucumbers to look pretty dramatic around 1 or 2 o'clock. That's ok. I never run for the hose when I see them flopping over in misery and you shouldn't either (unless it's catastrophic). You'll be doing yourself a disservice. Let your plants struggle a little. It only encourages them to grow stronger, deeper roots in search of water. As a result, you'll have a more drought tolerant crop then if you run for the hose when it gets a little uncomfortable outside. But there is a caveat, if your plant's don't bounce back when temperatures cool off around 4 or 5 then it's time to plan your watering schedule (or get a shade cloth for your veggies).
Signs your landscape is in distress.
Banana plants require lots of water and stress easily. Drought signs of drooping leaves and pale color are visible
Drooping plants late in the afternoon or morning
Wild lupine - Lupinus perennis, FL Native showing curling leaves due to drought stress
Wrinkled or curled leaves
Premature dropping of leaves
Browning leaf tips or pale in color
Impatiens - Impatiens walleriana, showing signs of extreme drought stress
Indicator plants. I am ashamed to say I still have not picked up a rain gauge. But I rely on drought indicator signs. Specifically of a few plants around my yard that I call my indicator plants. These plants are the first ones to show signs of distress and the first ones to bounce back after a good drink. A go to indicator for damp areas are impatiens. Although, nonnative they're a rare annual (or perennial in my garden) that bloom in the shady damp corners of my yard. They are thirsty plants and when the soil drys out in a usually damp spot, they put on a show as you can see.
Pokeberry - Phytolacca americana, showing signs of drought stress with droopy, yellowing leaves
The pokeberry is one of my all time favorite plants (and a favorite among birds and other mammals) is a spectacular indicator plant. Believe it or not, pokeberries have very long tap roots once established therefore, rarely need additional irrigation. So when this shrub starts to look flaccid, I know it is most definitely time to water. Since birds love these berries as much as I do, they'll happily spread them around your yard. Not only will you have more plants, you'll have more water indicators to assess microenvironments within your landscape.
What about lawns? In a world without HOA regulations, we would all have "Freedom Lawns" a sustainable mix of native grasses, flowers, sedges etc., that flourish in Florida's extremes and provide habitat for wildlife. However, many of us here in FL do not have that option and must abide by the HOA or pay, in the name of property values (wrong set of values but that's just my opinion). The amount you water (anything) should not change but the frequency may between seasons.
How much is too much? Deeper watering schedules used less often are more effective than lighter more frequent watering schedules. The idea is you want to encourage the lawns (or plants) roots to stretch down for water and nutrients. Light frequent waterings encourages shallow root systems and therefore, an easily stressed lawn. On the other hand, over watered landscapes and turf are just as detrimental as light frequent waterings. Our sandy Florida soils typically holds 1" of water in the top 12" of soil and UF/IFAS best management practices recommends 1/2" to 3/4" of water should be used per irrigation event in order to fully saturate the soil.
How Often? How often we should irrigate comes back to knowing the signs. You shouldn't irrigate unless drought signs are apparent. Once you irrigate or if it rains, then you shouldn't water again until those visible signs start to reappear. Stress in lawns looks a little bit different then it does in plants. Signs of drought stress include:
Folded Leaf blades lengthwise
Grass is showing a blue-gray tint
Footprints remain visible on the grass
Folded Leaf blades and blue-gray tint visible on St. Augustine Grass, drought stress indicators
Footprints remain on St. Augustine Grass due to drought stress
I know many of us set our irrigation on a timer and forget it. In reality, that may be causing more issues than it's fixing. Plants water needs change seasonally and different microenvironments throughout our landscape can have various watering requirements. So I encourage you to know the signs, watch your plants, save water and keep our landscape healthy.
Amelia's Native Wildflowers, LLC