Many people in the Twin Cities area are experiencing lawns flooded by heavy rains or the overflow from streams, rivers and lakes. The University of Minnesota Extension Service warns that during periods of high temperatures and sunlight in the summer, water that ponds on a lawn can cause significant damage or loss even within a few hours.
The damage occurs if the temperature of pooling water on the lawn is 80° F. Turfgrass death occurs in only a few days when this happens. The turf can still die even when water temperatures are lower because the water prevents oxygen from being available for the grass.
Other damage that can occur includes:
- sediment buildup
- fungal diseases
- moss and algae
- weed infestation
Minor flooding may be an indication that your lawn has drainage issues. LUNSETH’s landscaping crews’ have assessed and addressed this issue for a number of homeowners. Changing a lawns slopes and valleys can prevent flooding issues in the future.
The Extension Service goes on to warn that, in some instances, you may have to wait for a fix. The grasses we typically grow in Minnesota do not establish well in the middle of the summer due to the high heat and diseases that may occur. For instance, LUNSETH recommends waiting to seed until temperatures cool in the early fall (mid-August through early October).
Sediment buildup is likely following flooding and may result in needing to re-establish a lawn when silt has completely covered it. The process the Extension Service recommends includes:
- aerate in the fall
- overseed after aerating
- sodding can be done throughout the growing season
If you’re worried that your lawn has been damaged from too much rain or flooding, Organic Lawns by LUNSETH has the expertise to assess the problem and help you get your yard thriving again.
Perennials started popping up earlier than normal this spring. And our steady rains have helped mine thrive and I hope yours have, too. But we still need to make sure we do what’s needed to help them succeed through all the conditions a Minnesota summer will throw at them. Here are some great perennial care tips from our friends at the 
Prostrate knotweed looks a little like prostrate spurge, but it is easy to distinguish the two. The knotweed has symmetrical leaves that are arranged in an alternating pattern along the length of its runner. It also lacks the milky sap that is typical of the spurge. The knotweed germinates very early in the spring and can sometimes be found peeking through as the snow melts. It was identified at its earliest this year at the Turfgrass Research Center, in February! It looks a little like grass when it first emerges, and is sometimes mistaken for emerging crabgrass. The knotweed will usually show up six to eight weeks or even more, before crabgrass.
Yellow woodsorrel (better known as oxalis and shamrock), is an annual or a weak perennial in northern regions of the United States. It is easily recognized by its three-part leaf with distinct heart-shaped leaflets and its yellow flowers with five petals. It germinates in midsummer and often becomes a problem in August.
Black medic is considered an annual clover, even though it is not part of the clover
Prostrate spurge, as its name would indicate, grows in a prostrate manner along the surface of the ground. It has leaves that are paired opposite one another along the length of its runner. The individual leaves are asymmetrical, meaning that they are not the same on both sides of the midrib. Some varieties will have a purple/red spot on the middle of the leaf. If the stem is broken, a drop of milky sap will form at the end of the broken stem. This sap can irritate the skin, so wear gloves when hand pulling this weed. Spurge and knotweed can be mistaken for each other, but knotweed does not produce a milky sap when the stem is broken and its leaves grow in an alternating pattern. Spurge generally germinates later than goosegrass, which germinates later than crabgrass.
