Fertilization and Weed Control During Times of Water Stress

During hot summer months, when lawns begin to experience water stress, there is sometimes a temptation to postpone fertilizer and weed control treatments.  But because good nutrition significantly improves a lawns ability to withstand water stress, and because weeds compete for limited resources needed by the lawn, I usually advise that fertility and weed treatments continue, albeit with a program that takes the weather conditions into consideration.

With proper nutrition, a lawns root system and overall health is improved, enabling it to withstand a greater amount of stress, resist disease, and recover quicker when rains return.  A well-nourished lawn may still wilt and take on a “dried up” appearance during dry periods, as doing so results from a built-in mechanism to guard against excessive water loss, but will typically rebound completely after a good rain event.

During “normal” conditions, dark color is a primary objective of the typical fertilizer program.  This usually involves the use of at least modest rates of nitrogen fertilizer.  But because nitrogen also encourages growth, and in so doing increases demand for water, its use should be lessened during dry spells.  At Songbird, we rely on iron to aid color, as it intensifies the green without pushing water demanding growth.  Also, potash fertilizer is relied upon as it improves turf hardiness, helping the lawn overcome moisture stress and ensuing diseases associated with it.  Other nutrients impact hardiness as well.

Aside from what nutrients to supply, the source of respective nutrients is a significant factor.  Traditional, water soluble fertilizers should be avoided due to their quick release nature which may result in “burn” of the lawn.  Instead, the use of slow release and timed release products is called for, as these supply nutrients over an extended period of time, significantly reducing “burn potential”.

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Fertilizer choices may need to be altered when caring for a water stressed lawn

More and more, we are using a relatively new line of natural products that are designed to improve soil biology, and in so doing, improve lawn health and performance.  Though these products are quite costly, they can really help where lawns are significantly stressed.  Generally, they contain kelp, humic acid, and other natural ingredients.  Holganix, a product that we often use to help lawns under stress, also contains beneficial micro-organisms called mycorrhizae and rhizobacteria.  Establishing these “microbs” in the soil has long lasting benefits to the lawn, including an increased ability to withstand drought stress.

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Products designed to improve soil biology can indirectly improve turf over a longer period of time

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Holganix is a product that contains beneficial micro-organisms.  We must keep it refrigerated until used, to prolong the life of the “microbs”.

With regards to weed control, allowing them to establish while the lawn is struggling, as weeds often will, often results in the need of multiple treatments later on.  For example, “doveweed”, a weed that was unintentionally imported, has become a noxious weed that is appearing on more and more lawns.  Allowing weeds to establish may also result in a “thinner” lawn, as weeds simply out compete the grass.

With good nutrition and good weed control, most lawns will rebound well through water stress conditions.


— Brian