Tree care and woodland management

If you’re lucky enough to visit Beaver Creek Valley State Park in southeastern Minnesota, you’ll be treated to a crystal-clear, spring fed trout stream, magically mosquito-free forest, and a refreshing escape from the “real world” thanks to lack of cell phone or internet signal. The park also features surprisingly terrifying trails that lead up and across slippery, steep bluffs and through a variety of microclimates with wet forest, dry forest, and bluff-top patches of prairie.  What you won’t find is invasive buckthorn, a pernicious shrub that has taken over most of the woodlands in Washington County.

Forest and stream at Beaver Creek Valley State Park

Though buckthorn isn’t the only challenge affecting our local woods, it is often the first one that brings landowners into contact with the Washington Conservation District or University of Minnesota Extension – MyMinnesotaWoods program. When Minnesota Extension conducted a survey in 2018, buckthorn was the most common invasive plant reported by private landowners and public land professionals working in forested and agricultural settings. This non-native shrub spreads quickly and has a Medusa-like ability to grow back with even more branches after it is cut down.


Hands-down, buckthorn is the thing we hear the MOST complaints about at the Washington Conservation District #invasivespecies #forest #minnesota

♬ original sound – Angie Hong

If you are working to remove large areas of buckthorn, MyMinnesotaWoods staff advise that late summer and fall are the best times to cut and treat buckthorn stumps with herbicide in order to prevent regrowth. Select an herbicide containing glyphosate or triclopyr and apply the herbicide on the stump with a paintbrush, dauber, or low volume sprayer by covering an inch in from the edge of the outer bark. The center of the stump does not need to be treated.

Non-chemical options for buckthorn control include cutting and then covering stumps with black plastic, pulling buckthorn out by the roots, or cutting and then using regular mowing or goats (a crowd favorite) to limit regrowth.

A backpack sprayer with a wand makes it easier to treat buckthorn stumps in a large area without over-spraying or using too much herbicide.

As a result of this summer’s extended drought, many Minnesotans are also wondering how to best care for trees in their yards. If you have a well-established tree but are concerned it may be stressed by drought, experts from MyMinnesotaWoods advise that you dig down a ways into the soil around the base of the tree to evaluate the soil moisture. If the top nine inches of the soil are dry, you can use an overhead sprinkler to water the soil surrounding your tree, being sure to water the full area beneath the tree’s crown to reach all roots. Newly planted trees will need 20 gallons of water a week for the first three to five years, but only during weeks with no rain. Take care to avoid overwatering, as that will encourage shallow root growth and less resiliency in the future. Also, avoid pruning, as that will increase the risk of insects and disease.  

Newly planted trees will need 20 gallons of water a week for the first three to five years, but only during weeks with no rain.

This fall, Washington Conservation District and Wild Rivers Conservancy of the St. Croix and Namekagon will co-host a free online workshop for woodland landowners on Wednesday, October 20, 6-7:30pm. Speakers Danielle Shannon (US Forest Service), Tara Kelly (Washington Conservation District), and Kristina Geiger (Minnesota Land Trust) will discuss common topics of concern for woodland landowners, including:

  1. Managing invasive species such as buckthorn and garlic mustard;
  2. Building resiliency and adapting to changing climate patterns;
  3. Supporting birds and wildlife; and
  4. Protecting high quality habitat from development.

Register online at

In addition, woodland landowners can find a wealth of resources at or (tailored to Minnesota and Wisconsin woodland owners in the St. Croix River watershed).