Tropical Milkweed--Plant or Not?

A gardening friend of mine gave me several milkweed plants she had acquired at a plant swap this spring. I already had one variety in my garden, a short, bushy yellow plant that seeds politely around my garden. (By politely, I mean that I discover one or two new plants a year.) The plants my friend gave me were of "grab bag" variety. She did not know what kind they were but I was hoping for a purple one. Two of the plants soon bloomed and they turned out to be the common tall, yellow plants. Although I planted these in late spring, they have produced two bloom cycles this year.

The third plant didn't grow very fast and I almost forgot I planted it. Last week, I noticed some red buds on it, which later opened to a yellow center. I was thrilled that it was so pretty!

Asclepias curassavica?

After researching it on the web, I believe that it is Asclepias curassavica, tropical milkweed. I also discovered that tropical milkweed is the source of hot debate among butterfly enthusiasts. On the one hand, gardeners, hearing about the decline of Monarchs, plant milkweed because of its critical role in in Monarch reproduction, and tropical milkweed is a beautiful, commonly-available variety. On the other hand, tropical milkweed is much criticized across the internet for contributing to the Monarch decline. What's a good-intentioned gardener to do?

My research on tropical milkweed revealed a complicated problem. The gist is that the decline of the Monarch is partly attributable a parasite infection, and the infection rate is much higher for Monarchs that breed on tropical milkweed and overwinter in the southern part of the United States compared with those that migrate to Mexico for the winter. According to the Monarch Joint Venture, a partnership of government and private organizations to preserve the Monarch, the problem lies in winter-breeding made possible by the tropical milkweed rather than in the plant itself. As long as tropical milkweed is not available for winter breeding (that is, it dies back in the fall), it should not pose an increased risk of parasite problems for Monarchs. The Joint Venture recommends that in those warm areas where tropical milkweed might not die back in the winter, it should be cut back to the ground in the fall to ensure that parasite-free foliage is available for migratory Monarchs. (Click here for a full discussion of these issues).

So it seems that in our zone 7/8 gardens in the Memphis area, tropical milkweed bears watching. Since this is my first experience with it, I intend to watch mine closely as cold weather arrives and I'll give it a helping hand if it resists dormancy.

Dry Streambeds

In the last post, I talked about how the terraced beds we created were not enough to manage the run-off water we get from neighbors in heavy rains. The problem begins on the backside of the fence shown in the picture below. Although his house is not visible in this picture, the neighbor on the other side of the fence has the highest spot in the area. He has a dry streambed directed toward this fence, which, over time, has rotted out the bottom of his fence. The water flows onto our property at the top of our garden, approximately where the utility box can be seen . 

The former owner of our house installed a catch basin in this area with a drainage pipe that  runs underground to a location at the back part of the yard.  This was a good idea and usually takes care of the problem, but in heavy rains, the catch basin overflows. To take care of this problem, we installed a dry streambed to take the excess water down the slope in a more controlled way.

As you can see from this picture, the streambed makes a turn toward the fence and disappears behind shrubs.


We did a similar thing in the side yard to direct run-off from the neighbor's driveway toward the street. Water collects in a low spot between the neighbor's house and ours (assisted by a berm that Jack created) and then enters a dry streambed in the area shown below.

This dry streambed snakes around a tree in our front garden.

Then it makes another curve, discharging water into the side lawn area, then down to the street.

We just finished the last section of this streambed this summer and have had almost no rain since. Consequently, we don't know for sure whether the discharge from the stream will stay to the side lawn as we hope. We will be closely watching this area throughout the winter and if we find low places that allow the water to flow toward the lawn rather than down the hill, we will mark those places. Then, in the spring, we will lift the sod there and create a slight berm to encourage the water to flow toward the street.

I have found doing this work ourselves to be very satisfying (Jack might disagree . . . ), and I really don't mind that it takes us a longer time to get a finished product. Being amateurs, we seldom get it perfectly right on the first attempt and have to do subsequent tweaking. By my calculations, we will finish all our garden projects, about the time we're ready for the retirement home. But, for gardeners, that might be perfect timing!!

Solving Drainage Issues: Terracing

Last week I mentioned that in 2011 when Jack and I moved into our home, we discovered that several areas on our property needed drainage/water flow improvement. Professionals we consulted suggested catch basins with underground drainage pipes. While we had a catch basin installed in one area, in general, we preferred to use more natural landscaping techniques. In some areas, we mostly wanted to slow the water down so that it could be redistributed and used on our own property, rather than immediately sent to the sewer system. Of course, we needed any excess water directed away from our house. We decided we could solve most of these problems ourselves, using natural-looking methods like berms, dry stream beds, and terracing.

The first area we tackled was a side/back yard area that sloped away from our neighbor's mostly-concrete backyard toward our house. Here's a picture of the way that area looked when we moved in. The former owners had planted a small dogwood and there were a few azaleas and ferns planted here and there. Random stones were scattered around. The elevated area in front of the trees is an ivy-covered rock wall that was built by the former owner to hide an area where a drainage pipe was exposed.

Here's another "before" shot taken from farther back in the lawn.

In a heavy rain, water sheeted across the neighbor's concrete parking area and washed across the slope toward our house. We wanted to slow this water down to allow it to soak into the soil, while channeling excess away from the foundation of our house. To accomplish this, we decided to create a series of terraced beds bordered by short, dry-stacked stone walls.

Here's a recent picture of the the uppermost part of that area.

I would like to say that we began this effort with a full blown plan but, in fact, it "unfolded" as we went along. We first ordered two pallets of stone and built the beds closest to the neighbor's parking area. With practice, we got better at stacking the walls, and later walls we built looked better. We planted densely in this area to soften the hardscape and minimize bare ground.  When these plants mature in a few years, the walls will blend into the landscape.



The first obstacle that water meets as it comes off the neighbor's parking area is a thickly-planted bed of green liriope, bordered by a low stone wall. This grassy area both slows the water and controls erosion. We also brought in soil to decrease the slope within each bed. The combination of low walls, improved soil, and flatter terrain has slowed the speed of water flow, allowing more water to permeate the soil.

The following year, we started on the lower beds. The "sunken" pathways in the lower area serve as channels to direct any excess water away from our house. These pathways are actually at natural soil level but appear lower as a result of the slightly elevated beds that surround them. 

Although the terraced beds improved water retention in this area, the fact that the neighbor's adjoining area is nearly 100% concrete means that a lot of water is directed toward our garden in a heavy rain. The sunken pathways direct the water that can't be absorbed away from our house. We've tried using shredded bark and pine straw as mulch for these pathways, but both materials wash away in a hard rain. So, at least for now, the paths are not covered.


Another view of this area from a slightly different angle shows part of several flat stone paths that we created. These paths end with a slightly elevated border to maintain the flow of water inside the "sunken" pathway. The river rock (scattered in the path just below the flowerpot) are not a part of the path but were being temporarily stored there while we built a dry stream bed in another area. More on that in a later post.

To separate the lawn area from the garden, we decided to switch from natural stone to a single layer of retaining wall blocks. The blocks provide a more uniform surface for edging where the beds meet the lawn, and they are quicker and easier to put down. To make for a smoother transition to the natural stone, we extended the blocks up a bit into the garden area. 

For the most part, we were pleased with both the appearance and functionality of our terraced beds in this garden. However, in very heavy rains, a problem persisted in one area. I'll tell you how we handled that in the next post. Think "dry stream bed."

A Tribute to Three Trees

Yesterday Jack and I had three trees removed in our yard. The first was a maple. It must have started from a seed that hitched a ride on the wind and planted itself too close to a large gum tree. Its limbs were twisted in strange directions from trying to reach the sun. This past spring, we noticed a termite infestation in the lower part of the trunk, and when we investigated, the trunk was nearly hollow. 

The second was a large, old, wild cherry tree that had apparently been struck by lightning in years past. The top part of the central leader was gone, leaving a gaping wound that appeared rotten. The tree was in the back part of our lawn, closer to a neighbor's house than our own, and one of the large horizontal limbs that remained reached across the fence onto to their property. The neighbor had told me that several years ago, one of their own trees had blown over, doing a great deal of damage to their house, and they were nervous about this tree. We had an arborist look at it, and he thought the tree probably had a good deal of rot in the trunk.

The third was an old redbud growing near a pathway at the edge of a small grove of trees. When we moved into our house four years ago, the tree was leaning badly, but I was fond of the way its branches draped over the pathway, almost making an entrance to that part of the garden. Its gnarly, old trunk was riddled with holes and its bark was ragged. We considered taking it out last year because I was afraid it might fall one day and injure one of the grandsons who liked to play in that part of the lawn. 

I was sad about having all these trees removed. I was sad that the maple never had a good shot at life but had made a valiant effort to grow where Mother Nature planted it. I was sad that the cherry would no longer provide food and sanctuary for the wildlife in our backyard. And I was sad that spring will arrive next year without the pink blossoms of the old redbud.

I think that one of the men in the crew realized how I felt about cutting down these trees because he came up to me just before they left and said, "I thought you might like to know that the wood from the cherry tree will be put to good use. Cherry gives a wonderful flavor to meat and I plan to take it home with me to use in my smoker." I can't tell you how pleased I was to hear that. I thought of the book "The Giving Tree" by Shel Silverstein (if you haven't read this, you must). Like the tree in the book, that old, wild cherry will be giving for a little while longer.

I'll resume my discussion of solving drainage issues next time. Please forgive the digression.

Solving Drainage Issues

When Jack and I moved into our house about four years ago, we discovered that we had inherited water movement issues that were not readily apparent when we bought our house at the end of a very dry summer.  The 100-year flood of 2011 enlightened us. We quickly discovered where all our problem areas were. Thankfully, we suffered no actual damage--all our problems were of the nuisance variety, for instance, lawn areas that stayed wet too long and mulch that kept escaping the beds and running into the lawn. One by one, over the course of the past four years or so, we've gradually been finding solutions for those problem spots. In the next few posts, I'll share those solutions.

But first a little context . . . . Our house sits at a higher elevation than most of the houses in our neighborhood. But, as you can see in the photo below (taken when we bought the house), the neighbor's house (let's call him neighbor #1) is at a slightly higher elevation and has mostly concrete back and side yards that slope toward our house. Our house is to the right and not visible in the picture. This lawn area is in the front of our house.

 Neighbor #1's downspouts empty directly onto this concrete area and so the water ends up in our front, side, and back yards. The neighbor behind him (different development, elevation a little higher still) has a pool in his backyard so most of his rainwater flows onto his pool deck and runs into channels directed toward neighbor #1's backyard. So, that water eventually ends up in our yard as well. Here's another view, this one from our backyard. Neighbor #1's house is at the top of the incline.

As you can tell, the former owners of our house were not much into gardening. In fact, they called the area shown in this picture "the wilds" and left it as an untended, natural area. This sight might frighten away many potential buyers, but for a recently retired, garden enthusiast, it was a blank slate with a lot of potential. 

The former owner had installed several catch basins at the top of the incline and directed the water away from the house using buried drain pipes. He had also attached drain pipes to the downspout on this side of the house and, to avoid cutting a lot of tree roots, did not bury them but rather disguised them using a stacked stone wall. This wall (covered with ivy) can be seen in the picture, just in front of the trees. All this helped but did not completely solve the problem.

In future posts, I'll show you how Jack and I found solutions for our problems using natural devices like swales, berms, and dry stream beds.