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Gardening Tips Soil & Fertilizers

Soil pH for plants: All Things You Need to Know

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Types of Lime Explained

Hydrated Lime

This is fast acting but does not last well in free draining soils. It is very effective to produce a fast change in pH level, and suitable for all types of heavier soil. It is also the strongest form of lime generally available, and some sensible precautions should be taken to keep it out of your eyes and off exposed skin. Sensitive skin may be at risk of irritation or burns.

Ground Limestone

This is natural limestone which has been ground to a powder. Its speed of effect and persistence in the soil will depend on how finely it has been ground. Generally, it is less strong than hydrated lime, needing about 30% more to raise the pH by the same amount. It is also usually cheaper than the hydrated lime, and because it works more slowly and lasts longer, it is more suitable for use on light sandy soils.

Ground Chalk

This is very similar to ground limestone, though it is often more readily available in some parts of the country.

Mixed Lime

This is usually sold under a brand name. It contains a variety of particle sizes so it will give some immediate effect then go on for a long period. The strength is usually between hydrated lime and grounds limestone.

Soil testing FAQ’s

I am not a professional gardener; why should I be testing my soil?

Taking cues from pros is never a bad idea. A soil sample is affordable, quick, and invaluable if you’re shooting for a good season. Many good-intentioned homeowners profess a great devotion to their lawn or garden but end up pumping it full of unnecessary chemicals that are at best wasted and at worst hazardous to the environment. A little time and money up front can lead to greener, lusher plant life and a substantial reduction in cost.

How often should I test my soil?

Definitely at least once to know what you’re dealing with. The only way to ascertain whether the soil is acidic, neutral or alkaline is with a soil test. Upon learning the composition of the soil, your decisions on what to grow and how to care for your lawn will be much more educated. Much like carpentry; measure twice and cut once. Before making any major landscape changes, test your soil again to prevent unforeseen problems due to changes in soil composition.

What are my options For Soil PH testing kit?

Kits are available at garden stores everywhere. They are affordable, easy to use, and fairly reliable. It is important to follow the instructions closely and use distilled water with soil testing kits. And since you are probably not a geologist, it may be a good idea to corroborate the results with a second test.

If you live in an area with an agricultural university, they probably offer this service for around ten dollars. You can rely on the results to be accurate and thorough. There are also plenty of commercial labs advertised in gardening magazines, stores and on websites.

How do I take a sample?

The instructions will be specified on your test kit or by the testing agency. Overall you want to avoid testing recently treated soils, use sterile equipment, and take your samples from 3 to 6 inches deep. If you have several purposes for your soil, you may want to test separate samples to account for any variances.

What is this going to tell me?

A thorough test will tell you the consistency of your soil, the presence of organic matter, and the pH level. If your soil is loamy, you will treat it differently than a soil with more clay. Specific knowledge of organic matter can glean information on proper treatment plans, as can knowing the pH level. Usually, labs don’t test for everything, so tell them if you want your sample tested for lead or other specific nutrients. A gardening center or lab can then assist you in how to turn the results into a plan to keep your yard healthy.

PH Plant Preference Lists

The lists of plants below take you to the various classes of plants from lime haters to lime lovers.

If you find a plant which from your experience you think is in the wrong category, or you can add a plant form your own experience, please email me.

So far as I know, this is the most comprehensive list available anywhere. I hope it will enable you to select plants that are suitable for your soil if you leave it as it is, or help you to identify what pH would be best for the plants that you want to grow.

Plants are listed here in columns according to the pH level they prefer.

Note that some are very sensitive to pH levels outside their tolerant range, in which case they will appear in more than one column even though they are colored yellow as being “sensitive”.

A plain background means the plant is fairly tolerant

pH Plant Preferences of Vegetables, Fruit, Herbs and Food Plants

Vegetables, Fruit, Herbs and Food PlantsVegetables, Fruit, Herbs and Food Plants

PH Plant Preferences of Ornamental Plants



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