A Planting Strategy for Starting a Large Native Plant Garden

I am trying for the first time to start a native woodland planting under a couple of very large sugar maples. That means killing off the lawn under the trees and putting in understory trees, shrubs and the forest ground layer. Most importantly it means retaining all the leaf litter each fall that makes for a rich forest floor.  Although there is more than one way to tackle this project, I thought I would share how I am doing the ground layer in case it is helpful to someone else.

Since these two trees each have a canopy about 65-70 feet across, I used Round-up to kill the grass underneath, which I know not everyone is willing to use.  After that I am covering  the entire area with a layer of wood chip mulch, only about 2.5″ thick so as not to smother the tree roots but enough to bury and prevent germination of all the weed seeds laying on the ground.  The wood chip layer is too thick to allow planting seeds for at least another year. So I gathered together small starter plugs of woodland plants, either growing my own or through nursery orders, and I am planting them throughout the mulched area. Small is key because I could not dig large holes without hitting lots of tree roots. Then I used little pieces of bamboo stake with bright pink plastic ties to mark each planting so I would not accidentally walk on the little starter plants.

This photo is taken about 6 weeks after these plants went in so they are starting to be visible.

(You can ignore the rather strange looking patterns in the mulch due to different colors.  We had to use multiple mulch sources when our first source ran out.)

 

I selected plant species (mostly wildflowers) that are well known for spreading by underground runners or for their significant ability to re-seed. Hopefully in another year, the plants will be large enough to start spreading on their own when the mulch is significantly rotted. I have done this mulch technique in another setting and it worked well. 

The newest thing I am trying is use of clear plastic drinking cups to start grass seed at the same time, without waiting for the mulch to rot.  It was an inexpensive experiment that I thought could easily end in 100% failure, but it seems to be working. Using clear plastic cups (preferably #2 plastic), I cut away the lower third to one-half of the cup.  I marked each cup with a letter code using a black magic marker so I would know which seed I had used.

I made a set of 2-3 wire hooks for each cup, using some scrap wire I had. I scraped back a little patch of wood chip mulch, inserted the cup and anchored it to the dirt with the wire hooks, and then pushed the wood chips back around the base of the cup. I dropped a few grass seeds into the cup and either covered the seed with a teaspoon of dirt and left the seed exposed to the light, depending on seed instructions. I figured the plastic cup would let in light and keep rain from washing wood chips down on top the seed.  After about two weeks, I have grass coming up in almost all of the 24 cups I did. Once it comes up, it grows fast to reach the brighter light at the top of the cup. I plan to remove the cups once the grass is high enough to survive on its own.

This process seems to be a fast, easy and cheap way to get grasses started early in the process.  Most native grass species only need cold winter storage (which the vendor has already done) in order to germinate so I didn’t have to worry about cold damp stratification over winter like I would with most wildflowers.  I tried it with two shade-loving species of Tennessee native grasses  — Silky Wild Rye (Elymus villosus) and Leafy Satin Grass (Muhlenbergia mexicana.) Now that I know it seems to work, I am getting ready to do Bottlebrush grass (Hystrix patula), which is one of my favorite woodland grasses.

This process uses lots of mulch so I needed to find inexpensive sources.  I used two — getting them for free from a local tree service company and for a small fee from a local city’s solid waste recycling center.  If you live in northeast Tennessee, I highly recommend Jonesborough’s solid waste recycling center.  The chips are aged a nice dark color, nicely shredded, and you can get them in either of two versions — slightly decayed and moderately decayed.  The city loads them for you as part of their fee of $10 per truck load, but be sure to bring your checkbook because they don’t take cash.