Culvert planters, Part 3: Herb garden

In Part 1 of this series, I described a singleton culvert installation that I'm using to develop the root ball of a Meyer lemon tree. 

In Part 2, I showed a triple culvert combo I'm using to contain the specialized conditions needed to cultivate (yum!) blueberries, which cannot grow in unmodified greater Houston soils. 

Photo taken before the vegetables were removed and blueberries installed. 

Part 3 is also a triple combo, but rather than a clustered staggering of height, it's the equal-height linear array that the useable space called for:

Organic herbs elevated above both drainage and dog poop.

You can see the obvious difficulty - talk about sub-standard real estate.  I have long bemoaned the microscopic size of our back yard and the restrictions it places on my gardening efforts - I need every inch I can get, and I don't have that many inches to work with.  But as they say, necessity is the mother of invention, and nowhere has that been more true than in this location.  I literally had only two feet of width available, because there's only a five-foot set-back between the fence (and property line) and our eastern patio slab. 

This area next to the fence is also the principal drainage swale for our property.  During heavy rains, it will temporarily submerge beneath six or eight inches of water.  Even if I had wanted to plant anything edible on grade here, it would never survive.

Here's a view through the fence gate during construction.  Those concrete pavers were just thrown down semi-randomly as a temporary measure.  I wanted to get the landscaping finished in this area before deciding what kind of walkway to put here.  Retaining three feet of clearance is just enough to squeeze lawnmowers, wheelbarrows, trash carts, and other equipment through this corridor.  Oh, for just another five feet of yard width...

The build sequence was similar to what I showed in the first two culvert posts.

Equal heights were important for visual cohesion in this case.  I basically ripped out sod and leveled the three of them. 

I knew I'd be infilling the base with bull rock, which looks nice and also helps to move the stream of storm water efficiently through the area.  Landscape fabric beneath the rock helps to minimize weeds.   

The quality of the soil will impact how tasty the herbs are.  I did a blend of stock soil (poor quality), composted manure, Microlife natural fertilizer (a Houston company), and...

...leaf mold compost from Nature's Way Resources in Conroe (sold in Clear Lake through Maas and a few other local vendors such as Faith's Garden Shed Naturally).  Do you see that inky dark color?  Dark is good.  Dark means fertility. 

Once again, I liberated long-suffering plants trapped in substandard pots, including this small root-bound bay tree. 

The current array of herbs.  Yes, there are a few insect holes chewed in the sage, but that's to be expected with organic growing.  You sacrifice a bit of yield in exchange for no chemical residues and far better taste. 

As with other types of elevated gardens in our subtropical area, the main thing to keep in mind is that evaporation losses will be higher than for plantings on grade.  Raised gardens of all types need to be watered frequently and consistently because they dry out more quickly during our mean season (summer). 

As with the other culvert gardens, the cost of this installation was minimal, perhaps $30, which is low mainly because I rescued the culvert scraps from a disposal site and thus did not have to pay for them.  The bull rock was only $0.06 per pound at Wayne's Landscaping on Dixie Farm Road, and the rest of the expense came in the form of plants, soil, and amendments.

We haven't yet decided how to best upgrade this paver path into something more permanent.  Our residential gas line runs under this area, so we're hesitant to add a permanent cover.  More on that in a future post.