Size of grow hole

I am growing in an area with clay-loam that was farmed for a long time and then left fallow. There are some grasses and bushes growing, but nothing looks really healthy.
My plan is to dig planting holes for the six plants I plan to grow. What size should they be, how should I construct them and with what should I fill them?

Tennessee T,
Whites Creek, Tennessee

The soil in the field is tired and requires rejuvenation or replacement to support vigorous growth. Your decision to use planting holes is a sound one because you wish to grow only a few plants.

The size of the hole and its contents are the two most important environmental factors determining how large the plant will grow. The other is the plant’s genetic potential regarding size.

Dig the hole using a pitchfork and spade. It should be at least a foot in diameter and 15 inches deep. Gardeners frequently create larger holes, digging cavities up to two feet wide and deep. Larger holes are especially important if the soil is clay-like and impermeable, and the water drains slowly.

The hole should be filled with planting mix that drains well and is rich in nutrients. If the soil is easy to dig into, then it can be used in the mix. If it is sticky, it probably contains a lot of clay, so only a small proportion, perhaps 20-25% should be mixed into the planting mix.

Some organic ingredients that can be added to the mix are compost, worm castings, composted manures, organic fertilizer mixes, kelp and seaweed mixes, rock phosphate, cottonseed meal, and hair ? which is the only fertilizer a barber friend of mine uses.

If the site doesn’t entail a trek, you may find it easier to acquire a high quality outdoor planting mix that is already enriched, and fill the holes with it.

If the soil is tired, but drains easily, you may not have to dig at all. Instead, loosen the soil in the planting area using a pitchfork and use water-soluble fertilizer to provide the plants with nutrients. There are quite a few well-balanced soluble commercial fertilizers, both organic and inorganic, that will provide ample nutrients when they are used regularly.

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