The Q&A Archives: Many plant questions

Question: I live in Glendale, AZ and have many things I'd like to do in our yard, but many problems/questions:
#1: our yards (front/back) are sloped, and would like to know how to level them more without taking away drainage. The earth we have is clay, and seems to only support weeds.
#2: there's a big pine tree in the front yard (on a downslope), and nothing around it will grow. I don't know if it's because of something poured out in that area, or what. There are patches of weeds right around the tree, but nothing else...I've also noticed that our tree doesn't look as healthy as the others in neighbors' yards.
#3: It seems that part of the front yard will not allow plants to grow. I planted hollyhocks against the brick wall years ago, and they lasted a while, but died off. Awhile after, I tried different plants inthe same area, but they didn't take off at all. The last thing I tried was a purple bougainvilla, and it died, while the red one planted at the oppsite end of the wall is great...Also, in front of that area (if you draw a line, it's pointing to the pine tree), a grapefruit tree I had planted also never took off, while the trees further down the line (inthe direction of the thriving bougainvilla) are fine. What the deal with the dead zone?
#4: The red bougainvilla has grown very tall, and now is brown and ugly (with the winter here)...when can I cut it back without killing it, but keep my yard from looking trashy?
#5: I'd like to transplant some

Answer: I admire your willingness to get out into the yard and make it beautiful. For starters, you are dealing with extremely alkaline soils which will dictate the types of plants you will be successful with. You probably cannot change the slope of the soil without disrupting the drainage so perhaps you might consider gardening in raised beds. Raised beds can be filled with amended soils and provide more hospitable growing spaces for the roots of your plants. If you choose not to install raised beds, try planting shallow-rooted plants so the roots do not have to deal with growing in calache (the soil type prevalent in the desert southwest).

It can be difficult to get things to grow under pine trees. They cast dense shade, their fibrous roots are shallow and will compete with the roots of other plants for moisture, and they drop needles which can acidify the soil. I'd recommend leaving the earth beneath the pine bare, or planting it with a shade-tolerant, acid loving groundcover such as vinca minor.

I suspect that the dead zone you describe has a lot to do with the acidity from the pine tree. Your bougainvilleas grow best in alkaline soils and the excess acidity from the pine has affected the one.

Bougainvilleas can be pruned at most any time of year in your growing region. I'd prune it back now so when the weather warms it will put out a new flush of growth. Transplanting can be done now, too. The recent rains should make digging easy and with more rain in the forecast, the newly transplanted shrubs should root readily.

Best wishes with your landscape!

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