When the native soil is high-clay and slow draining it is especially important for this soil to be amended with an appropriate formula. Plants fail and are then returned to the nursery; The most common visual appearance (above) is that of the original root ball being the shape and size of the nursery pot. When the surrounding soil is either poorly draining or very sandy and rapidly draining, this is what often happens. New roots are discouraged from growing into this very challenging soil.

Compost is an Organic material and various blends of planting mix, recommended to be mixed in with or replacing the native soil, is vital for helping microbes feed and grow. Beneficial microbes break down soil nutrients and make them available for plant uptake. This "living soil" with beneficial bacteria and Mycorrhizae fungi work in harmony with root systems. Roots require microbial assistance in order to grow.

Just guessing that you have high clay soil is not sufficient or good practice. There are six different categories of clayey soil and all have differing drainage rates. Which type is yours? You can ascertain the composition of your soil by performing a Soil Settlement or "Jar Test" Problems from incorrect amendment of your soil will show up in future years, not necessarily the first year. If you have a large property, testing several areas will be the best idea. Drainage tests can give a ball-park idea of soil composition, but the accuracy is poor.

Just as it is important not to overload a campfire with too much new wood, the amount of green (not fully composted) organic matter added should be in moderation. Whenever the need arises to add high percentages of organic material (higher than 45%); then the types of amendments and their percentage is very important.
Most Compost has (and should have) a reasonable high C:N ratio. This extra carbon feeds the soil microbes. Too much activity and these microbes can reduce available nitrogen from the plants. Resulting is pale leaves and poor growth.

using more stable organics like peat moss (much less green matter) can help. So, too can the addition of sand or perlite help. These have zero carbon, and excellent drainage characteristics. is recommended.

When blending the soil for planting; a portion of any High % clay Native soil will need to be set aside (not used for planting). The goal is to create a soil composition that favors the growth of new roots.
The Garden Calculator Pro I will specify what percent of the Native should be used, as well as the quantities of the other amendments needed. This is based on soil composition and the size hole it specifies for planting.

Once, having dug the planting hole, the compost is saturated with water, then measured. All amendments and remaining Native soil can be mixed together and used to surround the new rootball. Whatever soil is placed under the new plant it should be packed firmly. Avoid situations where the rootball "sinks" after being planted.

With high clay soil, simply adding some organic material will not improve drainage sufficiently. The only real way high clay soil can be "fixed" is by substantially changing the composition formula. This means eliminating some of the clay. This is why the Garden Calculator will sometimes recommend adding sand into the planting formula just as it recommends removing a portion of the native soil which is so high in clay. What is to be done with that portion of clayey soil which is not used will really depend on the homeowner's situation. Filling holes where nothing is growing - gradually putting it into the green waste container, or then some other use is - ok. Maintaining a high percent of clay in the soil surrounding the plant is not ok.

Clay is the foundation for adobe, and this can be used for making a number of useful things around the home. It does a great job of sheltering pets from summer heat. There are lots of ideas for using clay, but not for trying to grow plants. Amending soil is a very important practice for green thumb gardening.

When measuring the amount of native soil and various amendments the most handy and most common measuring tool is the shovel being used to dig and move soil. Actually measuring with a shovel is likely to increase errors. The amount of sand that stays on a shovel will be much less than the amount of other amendments or native soil.
A wheelbarrow or a tarp (laid out near the planting hole) make for good options for mixing. Compost should be wetted prior to measuring (substantial compressing occurs).
Plants typically come in a nursery pot, and this is a convenient device for measuring. The GC-Pro I, provides specifications for using the nursery pot provided with the plant.
A hula-hoe (if available & using a tarp), work well for mixing. A shovel works if using wheelbarrow is good for mixing the soil & amendments,
Do not plant into a dry hole! Generally you'll be putting an inch or so of amended soil beneath the plant. Tamp it down, and then apply around the plant root-ball; as per instructions from GC-Pro-I Analyzer.

The Garden Calculator Pro-I provides mixing ratios in cubic feet, or dry quarts (not shovels). In addition to a shovel-load changing between differing soil and amendments, Some shovels are much bigger than others.
Specific mixing ratios are provided, because the subsequent irrigation run-time and emitter count depends on the final soil composition to be correct in order to assure proper moisture depth, water use efficiency and plant health.

A plant is installed ONLY ONCE, but irrigated thousands of times through it's life. Waste adds up. Beautiful plants require appropriately deep and wide root systems. Take this extra effort at the start, and enjoy many years of beauty and health.

As mentioned, amending high clay soil will often include the recommendation for using some sand. When you looked at the information on "The Jar Test", sand settles first and will move downward in soil, while clay settles last and moves to the surface. Though this visible separation of soil particle sizes is not always this apparent, seeing sand at the bottom and very fine particles at the top is always obvious. The best sand to use is a fine or play sand that will tend to stay mixed with the native soil for a longer time. Construction sand is often too gritty or contains too many large particles, but even then will help to open up a slow draining soil. Doing the job right is the best idea. Know just how much clay is in your soil.

The Garden Calculator Pro-I will actually specify the amount of Native soil, and each of the various amendments to add and mix for surrounding your new plant during the planting process. It calculates the permeability of this "NEW" soil mixture in order to provide the correct number of emitters and the irrigation run time. It is IMPORTANT to amend according to these specs! Putting in too little or too much amendment changes the new soil mix composition to the extent that irrigation moisture will not reach the bottom of the planting hole, or in the case of sandy native soil; it may cause premature wilting of your new plant between waterings.