Soil questions for a gardener

Asked March 12, 2018, 2:23 PM EDT

Hello! I just bought my first house in Phoenix. I want to do most of my veggie gardening in raised beds, but there are a few plants (tomatoes, root veggies, and a couple of fruit trees) that I want to plant directly in the ground. It looks like the previous owners used fill dirt in the non-sod areas. How do I know if this is just fill dirt? If it is, would it need to be removed and replaced? And what's the best way to go about doing that, and what should it be replaced with? Thanks so much Lindsy

Jackson County Oregon horticulture raised beds

1 Response

Lindsy: Removing "fill dirt" would be a herculean task and an unnecessary one. Most of the soil in Phoenix area is good soil on the west side of Bear Creek, and runs into sticky clay soils on the East side. Depending on where you are located, that is the kind of soil you will be working with. Much of what you describe as "fill dirt" has generally not been imported into the yard, but rather scooped away from the immediate area where the house is built. Generally, this consists of the topsoil and a little subsoil (depending on the depth of excavation). You can test this soil's fertility and pH (acid or alkaline content) with an inexpensive soil testing kit available at a nursery or garden supply. It will probably tell you the soil is slightly acid (good for the tomatoes; not so good if VERY ACID for the fruit trees,most of which prefer a neutral to slightly alkaline soil). Root vegetables are adaptable to
The soil will likely lack nitrogen, which is a soluble nutrient and needs replacement on an annual basis. Any other nutrient "needs" can be addressed after the plant is in the ground, watered well, and begins to grow. As for root crops, you may need a raised bed, a grow tub, or containers to achieve the depth of loose soils needed.
One of the mistakes folks make in planting shrubs and trees (including fruit trees) is to dig a hole and fill it with imported or amended soil.This results in a plant's roots remaining in the "rich" soil and not spreading out into the "native" soil. Think of this situation as if the plant were trying to grow in a container. Not a good situation! Always refill the planting hole with the soil dug from it.
I would like to recommend a few sources of information that will help you as you plant your garden. For fruit trees, visit extension.oregonstate.edu, enter EC819 in the search box to download "Growing Tree Fruits and Nuts in the Home Orchard" and then EC631 in the search box for "Managing Diseases and Insects..." These are free pamphlets which will help you immensely. Your local garden supply should have a copy for sale of the Jackson County Master Gardener Garden Guide: "Growing Vegetables in the Rogue Valley". You can also obtain this book from the Jackson County OSU Extension Office at 569 Hanley Road, Central Point. I hope this information gets you off to a good start!