Tuesday, October 28, 2014

The APEX project, with paths, un-day 16

A small recent return to Denver brings a couple new developments to the APEX crevice garden.
1. It has a path ("Tan breeze" from Pioneer Sand to inquiring minds)
2. Some Sprinklers moved
3. Some places are too dry


The idea behind keeping the stones, gravels, and path in the same brown family is for two reason: to unify the surface colour of the hardscapes and allow to show the form (shape) of the mounds, and to allow the highest colour-contrast to be on behalf of the plants.  Since 90% of the plants will be only a few inches  tall, they need all the help they can get in such a massive area.

2.  Originally, I was told that pop-up MP-rotator irrigation heads would be safe if they were both among the rocks in the beds and imbedded in the path.  The nice irrigation fellas (Singing Hills Landscaping, Aurora, CO) knew better and say that the heads will get detroyed if left at the path level and stepped on over time, so they took on the challenge of re-routing the path-heads and putting those in the stones.  As tight as we arranged the stones, I was dubious how well they could get those heads in there and did not envy the tedious work it'd take to dig under/through our stones.  But they were doing it.

3.  Calling back to the reason that most gardeners in the dry west have not embraced sand as a growing media, some places in the garden became incredibly dry, even in not-too-hot autumn weather.  But I noticed that, unsuprisingly and not disastrously so, the south faces were drying out sooner (which is fine as well as welcome, we expected this microclimate fomation), but to a bad degree in places where the gravel was thin.

Arctostaphylox x miwukka 'Chocolate Drop'
(An Allan Taylor selection)

This is not  shocking, nor the end of the world.  The nice thing is, there is a flexible fix- a person can simply add more gravel to keep it moister longer.  So, in all, I fancy we will have to go back and carefully seek out and address those spots where the gravel setteld away  or were originally applied too thin. Gravel changes two things, which millimeter-for-millimeter, greatly impact the drying-out of soil:

1. Gravel absorbs the sun and does not transfer this heat down to the lower media as badly as open soil.
2. Gravel deflects the wind; protecting the sand from the drying movement of air. (like a wind-jacket or "slicker," as we westerners like to say)

Decreased air movement and decreased heat sounds like the opposite effect of a hairdryer, eh?

So, my worries are calmed by a fact others have long known:
Gravel is not a hairdryer.


Anonymous said...

I'm forever grateful for contractors with the technical skills to move (or even do) irrigation systems. Gravel and sand...very underrated for the more xeric plants...people just cannot get over chocolate cake soils and organic mulches not being for all plants!

I wondered about how gravel did not transfer heat downward into soil, maybe like how stone or rock houses stay cooler inside?

Panayoti Kelaidis said...

Kicking myself I didn't drop by yesterday (I wasn't too far away) but I have misplaced my camera...Looking very good. 90% of plants will be dinky? What about prickly pears? Surely you have a spot for them? But delos are under that height so they should be legit. Delighted with your progress:do you have a volunteer force in place yet? You'll need 'em!

ineedacupoftea said...

The question for Delospermas is nit whether to include them bu- how many can we fit!? A volunteer force is starting to coagulate.., if out of necessity to watch the first young'uns- Kevin (big Kevin) told me a Manzanita dried up already. Oh, the perils of living so far away.

ineedacupoftea said...


There was a study that showed gravel keeping the soil cooler than wood or rubber mulch. Wierd, eh? I think we forget that the hot feeling gravel gives us is because it's reflecitng it away from the earth...

I am so curious to see how gravel/sand behaves in the long run in our drier climate. Will dust/clay/debris gather and turn it into a soil proper over time? Do earthworms travel through, and therefore mix it? Can ants sustain the walls of their colonies in it? Will sand's fast-drying properties mellow over time? Strengthen? Will a person just have to get used to heavy establishment waterings for all new plants even if once established, a plant will go without? Will the sand, in fact, trap more moisture in a clay layer below it than otherwise would happen? Experiments!

I'm really jazzed to try mixing permeable gravels into sand. My roommate will wodner why the cups of dirt and rocks all over the table this winter...

Forever wondering when to hire out the irrigation work,