Gardening on the Moon ( GOTM )

Gardening on the Moon – Part I

Gardening on the moon is the best way I can describe how I find growing plants, primarily ornamentals, in the Sonoran Desert north of Phoenix, AZ. In New Jersey we would get significant rains so watering wasn’t too much of an issue. Of course we had to provide supplemental watering during parts of the summer, but there were sufficient deluges to make this a sometime task. One of the factors in classifying an area as a desert is the amount of rainfall received per year. A desert receives less than twelve inches of rain a year. In NJ, we lived in an area that received more than 40 inches per year on average.

The Dirt on Desert Mixes

Scarcity of water in the garden isn’t the only problem facing Phoenix gardeners. There is very little real dirt like we had in NJ. Oh yes, we have something that passes for dirt, but it has very few nutrients, is often just sand and often doesn’t do a very good job of holding water. In NJ I could add some peat moss to help with the water retention capabilities of the planting medium. The problem with using anything containing peat moss or similar substances in the Sonoran desert is that if it dries out, it is very difficult to wet again.

You probably have had the experience of trying to soak some peat moss and having it stay dry in the middle until you have soaked it and kneaded it for quite a while. Well, that is what happens inside the flowerpots when a peat-based planting medium dries out. Of course for cacti and succulents being on the dry side is not a problem so mixes for these true desert plants can contain peat moss or similar organic substances.

Now don’t get me wrong, there are plenty of gardeners who use prepared mixes with peat moss in them, but they need to be very careful about watering practices when doing so. A work around that I have tried with some success is to use the sandy soil in our backyard and add improved soil to it with some time-release fertilizer. One of the difficult things about our garden centers in the Phoenix area is that they don’t sell bags of soil; top soil or otherwise. On the east coast I could count on buying bags of actual dirt. It would sometimes be called topsoil, but it was made of real dirt. Out here they only have ersatz mixes which don’t always provide the desired porosity or nutrients. Next season I plan to try a local garden center to see if I can buy a small quantity of topsoil.

Pick a pot

Speaking of flowerpots, there is a problem there as well. Black or very dark flower pots when left in the sun all day may bake the plants inside. When I was taking the Master Gardener class downtown last year, I saw an agave that was limp and watery. It was planted in a black pot and literally baked in the sun. Although these are drought tolerant, sun-loving plants, attention must be paid to make sure that the pot will give the plant enough room and enough temperature moderation. I place my cacti in terracotta pots mulched with pebbles. One thing that visitors are surprised to learn is that not all cacti can tolerate full sun. People generally hear “cactus” and figure that the plant can be placed in full sun with very little water, but that is not always true. Some cacti can get sunburned and severely damaged.

Bringing Saint Peter (San Pedro) Home

We purchased a San Pedro cactus (Trichocereus pachanoi) from our local Target. I never thought I would find this specimen there, but I did. It had three columns, but one had been broken off. The remaining two columns were in very good shape and the plant was marked down 50% with an additional discount on top of that. I couldn’t resist. I brought the plant home and did some research. At Cal’s Plant of the Week** , they explain that in Oklahoma the plant has a tendency to get sunburned and they therefore grow it under shade cloth all year long. Well, I planted it in our courtyard in a spot that only receives full sun part of the day and it seems to be doing fine. The plant has nearly doubled in size.

As a bonus, the broken column sent out a new growth that I have since detached and am now trying to root for growing as a separate specimen. This particular cactus also needs more water than some so I make sure that during the hot summer months it gets watered every seven to ten days depending on how hot it actually is. I especially like the fact that this cactus was used by the ancient natives of Peru for religious and cultural purposes. The San Pedro can tolerate temperatures as low as twenty degrees although we try to avoid such exposure if possible.

One other thing about gardening on the moon, I mean here in Phoenix…when planting, it is more important than ever to try and group plants with similar cultural needs together. You wouldn’t want a plant that needs plenty of water near a cactus that needs very little water or sooner or later one of the two charges will suffer. Over watered cacti have a tendency to get diseased or just plain rot!

Gardening on the Moon, www.gardeningonthemoon.com, originally published this post

Article References:

Cal’s Plant of the Week – http://www.plantoftheweek.org/**

** As this article was posted, the Plant of the Week site was down. I am leaving the link in place in the event the site is restored in the future.