Adding to the Riverbed

Last summer I wrote about making plans to add some color and variation to the one end of the big dry creek bed which used to have a straight line of RR ties holding back a low terrace. I wanted to add dark red and yellow, and add variation to the straight line that was caused by planting along those RR ties.  I purchased the plants this spring, but waited until we added more rocks before we chose spots and planted them.  These plants came in 3.5" pots from Bluestone Perennials and I planted them the same day in the large fiber pots with Miracle Grow Moisture Control potting mix and Espoma Bio-tone Starter Fertilizer which is awesome stuff.  They took right off, and the roots were filling the entire pot.

I've learned a few things over the past few years about planting in this situation. 

Plant #1 2019

When we initially planted this project, I was just using gallon sized fiber pots and I have since changed to using wider ones measuring about 11x10.   I initially only cut a large enough hole to sink the pot.  This hasn't been a big problem.  As you can see, most things are thriving ...

The down side to planting so restrictively is that when the more vigorous grasses try to spread, they strain against the surrounding road fabric, which doesn't hurt them at all, but it makes it completely impossible to divide them.  Plants with smaller bases, such as daylilies or the shrubs do just fine.  I have widened some of those holes but a lot of them are exactly the same as they were when first planted.

Our initial planting was sixty holes.  The year after we added almost two dozen more. I may have added one or two more single holes, but the change in the size of containers occurred between the first sixty and the next round of mass planting.  At this point we are cutting the road stabilization mat twice the size of the large container, removing the native soil (packed gray clay) and replacing it with a mixture of clean and fluffy native soil and potting mix.

I set the pot in the hole a few times to check the height.  Another thing I have learned is to plant them higher than you think you should because they settle over time.  Maybe not the first year, but by the second year the plant will sink.  This time we also removed the fiber pots because the plants were filling the container, but not firmly rooted into the fiber, and this saves us from having to look at the rim of the pot for a year which drives my husband a little nutty.  After a year or two the fiber breaks down enough that you can just pop the rim off right at the soil line.  In the mean time it looks like a pot sitting in a hole...

We pack the soil in and water well to remove any air from around the roots.

Then the gravel and rocks are replaced right up to the plant.  When the plant grows it will push the gravel away with no problem.

The plants I chose are:

Penstemon Onyx and Pearls

Penstemon Husker's Red

Pennisetum Lemon Squeeze

Pennisetum Karley Rose

Onyx and Pearls planted elsewhere

Husker's Red with some late flowers

The Penstemons have beautifully shaded red and green foliage.  When they bloom in June they will be quite tall but when they are through you can trim them down to whatever height suits you.  Both of these plants bloomed in the containers while I had them in the garden and they were very easy to care for.  I planted a few more in the river bed in spots vacated by Cheyenne Sky Echinacea.  I have no idea why those plants died over a mild winter.  They had done well the winter before, but I had them planted in threes and I lost 8 out of 9 plants. The one I salvaged was planted in another spot and is doing just great.

The Lemon Squeeze grass was my solution to the "yellow" color.  It is a bright chartreuse and should produce seed heads fairly early in the season as the Karley Rose does.  The Karley Rose was rescued from the warf where it was struggling with wet feet this year.  I replaced it with Niagara Falls Panicum which should do OK with wet feet.