When working in your backyard garden or filling containers, the right soil can help your plants thrive. Soil anchors a plant's roots, supports its water supply, helps it breathe and offers the nutrients it needs to grow. This guide reviews the different types of soil to help you find the best choice for your needs. It will also help you test your soil to determine the amendments you can add to help your plants succeed.
Tip: When planting directly into the ground, use amendments to improve your native, in-ground soil. When planting in containers, use a potting mix formulated for adequate drainage and space for roots to grow.
Determining Soil pH and Soil Type
Your soil's pH level reflects its acidity and is measured on a scale from 0 (most acidic) to 14 (most alkaline soil). Plants tend to grow best in soil with a pH between 6 and 7. Certain edibles and grasses prefer more extreme levels.
- Before shopping for soil amendments, do a quick test of your native soil using a simple pH test kit. This will help determine if you should increase the pH with lime or reduce it with sulfur.
The three main components of soil are sand, clay and silt. Most soil combines these three. Depending on where you live, your soil may be sandier or have more clay. A "feel test" can indicate the kind of soil that is most prominent in your yard.
- Moisten a tablespoon of soil and roll it into a small ball.
- If the ball packs together and is moldable, it is clay soil.
- If you can form a 2 to 3-inch ribbon with your ball of soil, your soil has a very high clay content.
- If the ribbon falls apart or feels gritty, you have a mix of clay and sand.
- If the soil ball feels a little gritty and will not hold together no matter how much water you add, it's sandy soil.
Tip: In addition to lime-rich chalky soil, such types as peaty soil, silty soil and loamy soil are defined by their acidity and proportion of sand, clay and silt.
Soil Amendment Types
Good soil is developed to address specific planting needs. Soils can be premixed and ready to use or specially formulated for certain plants. You can also find individual amendments to add to your native, in-ground soil to improve the composition.
- Peat moss increases the soil's ability to retain moisture and nutrients while also improving drainage. It can absorb 10 to 20 times its weight in water.
- Soil compost and all manure types enrich soil and boost fertility. It helps soil to release nutrients to a plant continuously over long periods of time.
- Soil conditioner is added to soils to help prevent compaction. It is often used to help native soil that has been damaged or to promote strong root growth. It improves drainage and aeration when added to potting soils.
- Perlite is derived from volcanic rock that's been crushed and heat-treated into white, lightweight particles. When added to soil, it helps increase air space and improves water drainage.
- Lime increases the pH of a potting mix to around 6.0 and is ideal for plant growth in containers.
- Sulfur helps lower soil pH by reducing excess alkalinity. It provides plants with iron for lush, green growth and enhanced water filtration.
What Soil is Best for My Plants?
Soil is an important building block to growing strong, healthy and beautiful plants. Different plants need different types of support from their soil.
- Determine what you'll be planting before you pick out the corresponding soil.
- Carefully read the amendment and potting mix labels to ensure you've made the right choice for your plants.
- Feed your plants one month after planting and keep them properly watered.
Topsoil has different grades. Lower-grade topsoils are meant for filling and leveling holes and should only be used for that purpose. Higher-grade topsoils are great for conditioning or adding organic matter to the native soil. Neither grade should be used when planting.
Garden soil is a pre-mixed blend of organic matter and nutrients. It is designed to be mixed with your native soil to fix problems such as high or low pH, lack of nutrients and soil compaction. Garden soil is meant for in-ground use only.
Raised Bed Soil
Raised bed soil is used when building a raised bed on top of your native soil. Garden soil and native soil are too dense by themselves to provide adequate aeration and drainage in a raised bed. You can either combine a 50/50 mixture of potting mix and garden soil when filling a raised bed or use pre-mixed raised bed soil.
Potting mixes are formulated for use in pots or containers as they allow for adequate drainage along with providing space for plant roots to stretch out.
- As the size of a container gets smaller, the importance of these benefits gets larger. Since their roots can't travel far to find the food and water that they need, container plants need the extra help a potting mix can provide.
- Avoid misusing native soil and garden soil in containers. They don't provide the necessary drainage, airflow and room for roots to grow when used in containers.
- Potting mix should be replaced annually.
- Most potting soils combine peat moss, perlite and sometimes vermiculite. Most are sterilized to kill microbes that might cause plant diseases.
Right Plant, Right Soil
The different types of plants have different needs for their soil.
- Trees and shrubs need soil fortified with phosphorus and iron to promote root development and prevent leaf yellowing. Soil that provides continuous release plant fertilizer will help establish strong roots.
- Lawns benefit from soils that combine composted materials, fertilizer and water control additives for the best general support.
- Flowers benefit from soils that contain organic materials such as peat moss to allow for adequate drainage. Adding compost to the soil can help offset any shortages in the native soil. Lighter soils give flower roots room to grow, spread and anchor. Be sure to research the specific needs of your flower varieties.
- Fruits and vegetables belong in soil that can help manage moisture to protect your garden from over- or under-watering. Add compost and organic materials as needed to ensure your edibles get the nutrients they need for growth. Fruits and vegetables often have greater need for water than non-edibles. Learn and follow the watering rules for each type of edible plant you have.
- Succulents need very little water. Consider soils with such additives as peat moss, sand and perlite to help with drainage and prevent soil compaction.
When to Fertilize Plants
Many packaged soils contain added nutrients to give plants a quick boost or keep them fertilized through the growing season.
- Nitrogen, phosphorus and potassium are some of the most common nutrients.
- When choosing your soil, look at a product's label to see how long it will keep a plant fertilized. Some soils release fertilizer for up to three months. Others are formulated with nutrients that keep a plant fed for up to nine months.
- Many plants get the most benefit from added nutrition at the start of the spring growing season.
Learning the different types of soil for lawns and gardens provides a base for growing happy and healthy plants.
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