This article was reviewed by Steve Snedeker, professional landscaper.
As you figure out a schedule for your garden's growing season, you may be wondering how often you should add compost to the soil. So to help you out, we've done some research and found the most relevant information about compost, the best times to add it to your garden, and the best ways to do so. Let's get started!
To maintain healthy soil, you should add a thick layer of compost - at least 2-3" - every year. If you're using homemade compost, it's best to add it in early fall so that by spring, it will have broken down and worked itself into the soil. Adding a thick layer of compost in the fall also helps reduce weeds. However, if you're using bagged compost, it's best to add it to the soil in early spring just a few weeks before planting since it's already been broken down finely. You can also add a little less than if you were using homemade - usually a layer of about 1-2".
Additionally, you can add compost to your garden throughout the growing season, particularly in these circumstances:
- After significant storms throughout the summer to help restore any eroded soil
- When trees and vegetable plants are flowering and about to bear fruit, to give a boost of nutrients
- Whenever you notice the soil looking dense, sandy, or full of clay
- If you live in a warm place with a year-round growing season, you'll want to add compost to the entire garden at least twice per year
There are a few other things you'll need to take into consideration as well, such as deciding whether compost or fertilizer best suits your needs, learning how to add compost to either an established garden or an empty plot and more. It may sound like a lot, but have no fear - we have it all covered!
But let's talk about first things first. As you consider your composting schedule, you'll want to take into account the types of plants you have, as different varieties can require different amounts of compost.
How Often Should I Add Compost to Trees?
Compost can be added to trees at any time of the year. When working with trees, it's best to only use it as mulch sitting on top of the ground instead of digging it into the soil, particularly if you have fruit trees. Fruit trees, and many other varieties of trees as well, have a delicate network of roots just below the surface of the ground. Tilling the soil to work in compost will damage these roots and can cause the tree to lose its fruit and leaves, sometimes permanently. However, since the roots are so near the surface of the ground, they'll still feel the benefits of the compost even if it isn't tilled into the soil.
How Often Should I Add Compost to Vegetables?
Prepare the soil for growing vegetables during the previous fall by thoroughly mixing in compost. Then, a few times throughout the growing season, add a thin layer - no more than 1/2" - to continue improving the soil and adding nutrients to your plants. Some types of vegetables, such as tomatoes, squash, and corn, need extra nutrients, and can benefit from a monthly compost schedule.
How Often Should I Add Compost to Flowers?
Blend some compost in with the top layer of soil every spring, either before planting annuals or around your perennials. Add a thicker layer in the fall - at least 2-3" - to protect the roots of your perennials from the cold. Although adding small amounts of compost throughout the growing season won't hurt, it's not as necessary to do this for flowers as it is for vegetables.
How Often Should I Add Compost to My Lawn?
To add compost to an established lawn, "topdress" it by adding a thin layer of compost to the grass and raking it to blend it in. Ideally, this should be done several times per year, but just once or twice per year is incredibly beneficial as well. At a minimum, you should add compost in spring shortly after the grass has begun growing again and again in the fall. Midsummer is another excellent time if you'd like another topdressing session to your rotation.
Adding compost is also a great way to aerate the soil or to adjust soil that has a lot of clay or sand. Check out our article How To Improve Clay Soil for Lawns for more specific information on improving a clay-filled lawn.
How Often Should I Add Compost to Potted Plants?
Did you know that you can add compost to your potted plants? Add a 1" layer to the soil two times per year to give them a boost of nutrients. Compost can also help improve the drainage - read our article How to Improve Drainage in Potted Plants for more information.
How Should I Add Compost to My Garden?
When adding compost to your garden, you'll want to consider whether you're adding it to a garden that has already been planted or an empty plot that can be tilled. To add compost to an empty plot, spread 2-3" inches of compost over the ground and work it in with an electric tiller or digging fork. After this initial application, you'll only need to add half an inch per year to maintain quality.
If you'd like to add compost to a garden that is already planted, spread approximately 3" of compost over the soil and around your plants in the spring, you can repeat the process that autumn and the following spring to renew the quality of your soil thoroughly. Just make sure to only add a thin layer over seeds that were recently planted.
Is Compost Good For All Plants?
Compost can benefit any plant, but you need to aware of its content, the pH levels caused by this content, and the needs of your specific plants. For example, coffee grounds tend to be acidic, making them a poor choice for plants that need alkaline soil such as hydrangeas. However, as long as you are aware of the contents of your compost, it will always be a great way to improve the quality of your soil and increase the health of your plants.
Can I Add Too Much Compost to a Garden?
Even though conventional wisdom sometimes says otherwise, it is possible to add too much compost to a garden. This is particularly true for manure-based compost, which can have high levels of phosphorus. Although phosphorus is an essential nutrient, too much can cause problems such as iron and manganese deficiencies, ammonia toxicity, and the loss of certain fungi that help some plants function correctly.
Can I Plant Directly Into Compost?
Since compost is simply a soil amendment, not a soil replacement, planting directly into compost is not the best idea. The phrase "soil amendment" means that it's useful for adjusting and improving aspects of soil, such as adding nutrients or making it more aerated. However, plants still need nutrients from the soil itself to thrive. Additionally, compost is generally too lightweight to support a robust root system, and it's also too porous to retain an amount of water that's sufficient for plants to survive.
Is Compost Better Than Fertilizer?
Compost and fertilizer serve two different purposes, so you'll need to analyze your plants and soil to decide which is a better choice. To put it simply, fertilizer feeds plants nutrients, while compost works with the soil to make it a better environment. If your plants are lacking certain nutrients, you may want to consider fertilizer. However, if your plants are healthy but the soil is dense or nutrient deficient, compost is probably your best bet. Additionally, although the nutrients in compost are not as highly concentrated as in fertilizer, it still contains small amounts of chemicals that are necessary for plants to thrive.
With that being said, compost and fertilizer can also work together. You'll want to be aware of the contents of each to make sure you don't end up with too much of a particular nutrient. Caution is also necessary when using chemical fertilizers, as too much can throw off the soil's chemical balance. However, compost and fertilizer make a great pair since the compost can soak up the fertilizer's nutrients until the moment the plant needs it. Organic compost and fertilizer are always the best choices since they work holistically with both plants and soil.
Leave us a comment to let us know what you think. When do you add compost to your garden and how often?