By Marty Pawlikowski, CFRS Master Rosarian
It may not be exciting to read about watering your roses… But at this time of year, it’s about the most important thing you can do – water. Like all living things, your roses cannot survive without adequate water. With summer’s high temperatures, water is extremely significant for your rose’s survival.
Noted rosarian, Doc Allcott, wrote in the Wind Chimes several years ago that it has been estimated that three gallons of water are lost through a rosebush in a single day through transpiration. Transpiration is the passage of water vapor from the leaves through a membrane or pore. In a rosebush, the pore is the stoma located on the undersides of the leaf. There are hundreds of stomata on the underside of each leaf. When we are outside on a hot summer day we sweat (or should I say perspire?). And similarly, roses do the same thing through transpiration. Like us, our roses need a continual supply of water to replace the moisture lost through transpiration. High temperatures and full sun accelerate transpiration, depleting moisture rapidly, thus requiring more water.
So how much water does your rose garden need to flourish during the summer? Everyone’s growing conditions are different based on variables including soil type and contents, amount of sun received, whether the beds abut paved or turf areas, the quantity, type and depth of mulch, type of irrigation system, etc. These variables result in different watering requirements. Simply put, the amount of water you need to apply to your garden is variable dependent upon your particular microclimate and the amount of rainfall you receive. One way of determining how much water your particular soil needs is to pull back the mulch, dig down in the soil a little and pick up a handful of soil. Squeeze the soil in your hand. How well has it held the moisture from yesterday’s or even this morning’s watering? The soil should feel evenly moist, and when squeezed in your hand should form a mass that easily crumbles. Use common sense – if the soil shows no signs of holding together, then water more frequently or increase the quantity of water applied. Remember, deep thorough watering is preferable to light frequent watering as it encourages strong, deep roots. On the other hand, if when squeezed, the soil forms a soggy mass, decrease the quantity and or frequency of watering.
Typically the months of July and August are considered our “rainy season.” But this has not held true during the past few years. It is important to monitor the amount of water your roses receive. As a general rule our roses need between 2- and 3-inches of water per week. In periods of hot, dry temperatures, even more may be needed depending on the size of the bushes and the variables in your microclimate. Don’t assume that rainfall will furnish all the water your roses need; check the soil to be sure, and set up a rain gauge to monitor rainfall amounts. Typical of Central Florida, it may be raining cats and dogs where you work and be sunny — without a drop of rain — in your garden, and vice a versa. It is important that we conserve this natural resource and using a rain gauge will help us eliminate unnecessary watering.
Check the depth of your watering to make sure that the moisture is reaching the root system, which for established fortuniana grafted roses, is quite large. If water penetration of the soil is no more than 8-inches deep, longer or more frequent watering sessions are needed. Remember fortuniana roots are generally in the top 14 inches of the soil and very far reaching. Shallow watering will encourage shallow rooted plants. Make sure the water is getting down into the entire root zone. When watering a bed of roses try to water the entire bed – that’s where fortuniana roots are located (throughout the whole bed – not only under the drip line of the bush).
Watering is also important to bring oxygen into the soil. As water moves through the soil oxygen follows behind filling the spaces. Rain reportedly places more oxygen in the soil than any other means. Without oxygen in the soil our roses will decline and eventually die. New rose growers are often concerned with the saying “roses do not like wet feet.” As a result they underwater, believing that too much water will harm the “feet” (roots) of their roses. It is true that roses do not like to be grown in low lying areas where water tends to “stand.” The oxygen needed for healthy growth will not be available in waterlogged areas. If your rose beds have adequate drainage you really do not need to worry about “wet feet”. Over watering, or too much rainfall, can even when adequate drainage is present, temporarily deplete oxygen in the soil – the soil becomes waterlogged and the oxygen is displaced. Your roses provide the following watering indicators: too little water will cause the leaves to be limp and sagging; too much will starve the rose of oxygen and its leaves will turn yellow and drop off.
There are many ways to provide water for the roses from hand watering (a water wand is good because it gently deposits a large amount of water in a limited space for easy access to the roots), to various micro-spray systems or even individual bubblers for each plant. A rose plant needs water to the full depth of its roots (assume 14-inches), in enough quantity to keep soil constantly moist but not waterlogged.
Overhead sprinkling is a great way to cool off and refresh your bushes on a hot summer afternoon. Wherever there’s dust or air pollution, leaves benefit from overhead watering every week or so, both to remove dust and to wash away some insect pests — especially aphids. After several minutes under overhead sprinklers, you’ll be amazed at how refreshed your bushes look! Right about now you are probably thinking … “I’ve always heard ‘Don’t get the leaves wet!!’” Water on the leaves is not a bad thing – it will not spread blackspot if the leaves are only wet for a short time, and if you let your bushes breeze dry before nightfall. This mid-day overhead watering is only to cool down and wash off the foliage. Most of the water applied overhead is lost to evaporation and will not reach down into the root zone. However, water restrictions which are frequently in effect will prohibit the time and days in which you can perform this task — unless you are washing off the bushes by hand.
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