Feeding your plants sugar water is a popular gardening hack floating around on social media. Sugar water, the claim goes, improves a plant’s photosynthesis, and can help a plant overcome transplant shock. But does sugar water really do your plants any good, or is it an urban legend that can even be harmful?
Read on to get the low down on sugar water.
What Is Sugar Water?
Sugar water is a combination of tap water and sugar to be used as plant food. The sugar is usually added to hot or boiling water so it dissolves easily. The formulas how much sugar is added to the water vary.
The Idea Behind Sugar Water
In the process of photosynthesis, plants use energy, water, and carbon dioxide to produce sugars and starches. The idea of feeding a plant sugar water is based on the assumption that sugar provides additional carbohydrates that the plant takes up with its roots. The theory is that the sugar boosts plant growth.
How Sugar Water Affects Plants
There are several reasons why sugar water as a plant food doesn’t work.
Plants do not have a digestive system that metabolizes sugar like humans. What’s more, the sugar they produce is glucose, a monosaccharide, whereas the sugar from the grocery store that we consume are polysaccharides, more complex sugars consisting of a chain of monosaccharides and not easily broken down.
Not only are plant roots unable to take in sugar, giving them sugar dissolved in water even blocks the roots from absorbing water. And a plant that does not get water wilts and eventually dies.
Plants do photosynthesis on their own, self-regulating the amount of sugar they produce to grow. Their sugar needs vary depending on the life stage; a plant transitioning from the seedling stage to an adult plant typically needs more sugar than a mature plant. There is nothing extra sugar can provide to help this process along.
Also, soil that is saturated with a sugar solution can attract harmful micro-organisms that can affect the plant’s health.
There is no scientific evidence that feeding plants sugar water is conducive to plant health, on the contrary, it can harm your plants and even kill them.
Don't Use Sugar Water for Transplant Shock
What is said above about the detrimental effects of sugar water also applies to trying to revive plants going through transplant shock. When plants look sad and wilted after transplanting, it happens for two reasons. Either their leaves have been burned from too much sun too quickly because they weren’t hardened off properly, and as a result they cannot perform photosynthesis. Or, the roots were damaged during transplanting and they cannot take up sufficient water and nutrients.
Sugar water does not do anything to help plants with transplant shock, and it can make it worse. Often, plants recover on their own. Just give them time, keep them well-watered and protect them from too much sun to prevent more leaf scorch.
Only Use Sugar Water for Cut Flowers
The only exception where using sugar water makes sense is to add it to cut flowers to prevent them from wilting. That’s why florists often provide you with a small sachet of sugar-based plant food to add to the vase.
Unlike plant roots, the stems of cut flowers can absorb the sugar, which revives their carbohydrates. Sugar sends the flowers the false signal that the plant is alive and well and should continue blooming. This effect is merely temporary and eventually the flowers die.
What to Feed Plants Instead of Sugar Water
First and foremost, make sure your plants get enough sunlight and water so photosynthesis can take place. To provide them with the nutrients they need, give them the right fertilizer, either an all-purpose fertilizer, one that has a higher nitrogen content to promote leaf growth, or one that is higher in phosphorus to encourage blooming. Follow the fertilizer directions, as more is not better.
Using Sugar Water to Attract Pollinators
There are studies about using sugar-water solution on plants to attract beneficial insects. The sugar works like as an artificial honeydew and researchers found that it attracted adult lacewings, lady beetles, adult weevil parasitoid, big-eyed bugs, minute pirate bugs, and adult hoverflies. But this does not mean that spraying your plants with sugar water is something you should be doing. As a home gardener, you are much better off—and it helps biodiversity much more—if you plant natives that naturally attract beneficial insects and pollinators. Let those plants produce their own sugar via photosynthesis, which they’ll do without human interference.
Research on Sugar Applications to Crops. Cropwatch. University of Nebraska-Lincoln, Institute of Agriculture and Natural Resources.