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Compost is an extremely popular and useful soil amendment that most gardeners can’t go without. Perfect for adding nutrients and breaking up heavy soil, it’s often referred to as black gold. So if it’s so good for your garden, why use soil at all? What’s to stop you from growing plants in pure compost? Keep reading to learn more about the wisdom of vegetable growing in compost without soil.
Compost is often referred to as “black gold” by gardeners due to its ability to enrich soil with essential nutrients improve soil structure and help maintain optimal moisture levels. As you plan your vegetable garden or flowerbeds, you may be wondering can I plant directly in compost?
While the rich, organic matter in compost makes it tempting to use as the sole growing medium for your plants, there are some important factors to consider before planting in pure compost
Using compost improperly can lead to issues with water retention, nutrient balances, and even toxicity, which can negatively impact plant growth. Understanding the properties of compost and how they interact with plant needs is key.
This article will explore the do’s and don’ts of planting in compost, including:
- The benefits and potential drawbacks of using pure compost as a planting medium
- What types of plants are best suited for direct planting into compost
- How to prepare and amend compost for optimal planting results
- Step-by-step planting instructions and care tips when growing in compost
- Troubleshooting challenges like pests, diseases, and watering issues
- Finding the right compost-to-soil ratio for different gardening needs
Follow these tips to successfully use compost in your vegetable and flower gardens,
Can You Plant Seedlings Directly in Compost?
Planting directly into pure, undiluted compost is generally feasible and can provide some benefits thanks to compost’s rich nutrient content and organic matter.
However, it’s crucial to assess the maturity and stability of your compost before planting. Immature compost that is still decomposing can harm plants due to high heat levels and the dynamic microbial activity occurring during the breakdown process.
Mature, finished compost that has fully stabilized provides a much safer environment for planting. Even so, mixing compost with topsoil or garden soil is advisable to create better drainage and aeration for plant roots.
What Types of Plants Do Well in Straight Compost?
When deciding which plants may thrive with direct planting into compost, consider ones that naturally prefer nutrient-dense, organic growing mediums. Some top options include:
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Vegetables: Most vegetables like tomatoes, squash, cucumbers, peppers, and carrots appreciate compost-rich soil.
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Herbs: Pungent herbs such as basil, parsley, cilantro, and dill often flourish when grown in compost.
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Flowers: Compost helps provide nutrients for flowering annuals like marigolds, zinnias, sunflowers, and cosmos.
Certain plants that require fast drainage or low-nutrient environments may struggle in pure compost, for instance succulents, wildflowers, and some native plants. Always research your plant variety before planting.
How to Prepare Compost for Planting
To ensure your compost provides the best medium for your plants, it’s important to achieve the right balance of nutrients and organic matter before planting:
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Mix brown and green materials – Good compost contains a blend of carbon-rich “browns” like dried leaves, straw, or shredded paper, and nitrogen-rich “greens” like fresh grass clippings, coffee grounds, and vegetable scraps. This creates a balanced nutrient profile.
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Allow proper decomposition – Finished compost should be dark, crumbly, and earthy-smelling. Test compost maturity by planting a few seeds; if seeds fail to thrive, the compost needs more time to break down.
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Screen for sticks, debris – Remove any sticks, stones, or undecomposed bits which may obstruct root growth.
By preparing compost properly, your plants will have the ideal growing environment right from the start.
Step-by-Step Guide to Planting in Compost
Follow these simple steps for planting directly in compost:
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Assess compost maturity – Compost should be well-aged, stabilized, and nutritionally balanced before planting.
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Moisten compost – Hydrate dried compost a day before planting to allow moisture to penetrate. Proper hydration encourages root growth.
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Dig holes – Dig holes or trenches just wider and deeper than each plant’s root ball.
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Place plants – Carefully place each plant in its hole, handling the stem gently.
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Backfill soil – Surround roots and fill in holes with compost, gently firming around stems.
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Water thoroughly after planting to soak the root zone. Let soil dry slightly between waterings.
With the right preparations and planting techniques, your plants can get off to a vigorous start in compost-based soils!
Ongoing Care When Growing in Compost
Caring for plants growing in pure compost takes some adjustments in watering, fertilization, and pest/disease prevention:
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Water frequently – Compost dries out rapidly. Check soil moisture daily, watering when the top inch becomes dry.
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Replenish nutrients – Test nutrient levels every 2-3 months. Mix in balanced organic fertilizer as needed.
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Control pests – Compost can harbor fungus gnats. Use sticky traps and let soil dry between waterings.
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Adjust compaction – Loosen and mix up compacted compost monthly to improve drainage.
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Control weeds – Stay vigilant in removing new weed growth before it overtakes beds.
With attentive care, your compost-grown plants can thrive all season long.
What Is the Best Compost to Soil Ratio for Planting?
Most garden experts recommend using compost as a soil amendment rather than the sole planting medium. Blending compost with topsoil or garden soil provides the ideal balance of nutrients, drainage, and moisture retention for healthy roots and plant growth.
Here are suggested compost-to-soil ratios to mix for planting:
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Vegetable gardens – Mix 1 part compost with 2 parts soil
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Flower beds – Use 1 part compost to 3 parts soil
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Potting mixes – Blend 1 part compost with 2 parts potting soil
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Seed starting – Mix 1 part compost with 3 parts seed starter mix
Always assess the nutrient content of your compost and adjust proportions accordingly. Very nutrient-dense manure compost may work best blended in a 1:4 ratio with soil.
Troubleshooting Planting in Compost
Growing in pure compost can sometimes cause issues with plant performance and health. Here are some common challenges and how to resolve them:
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Nutrient deficiencies – Mix in organic plant food or blood meal.
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Leggy seedlings – Increase light exposure, use heating mats.
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Poor drainage – Add extra perlite or horticultural sand.
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Nutrient toxicity – Leach pots with clean water to remove excess salts.
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High compaction – Loosen compost layers using a garden fork.
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Excessive moisture – Reduce watering frequency, allow soil to dry out between waterings.
With attentive soil management and amendments, compost-related issues can usually be overcome.
Key Takeaways on Planting in Compost
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Pure compost lacks the ideal structure for roots. Mix with soil to improve drainage and stability.
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Leafy greens, herbs, flowers, and vegetables often thrive when grown in compost.
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Mature, finished compost is safer for direct planting than fresh, unfinished compost.
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Test compost by growing seeds; healthy germination means it’s ready for planting.
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Adjust watering, fertilization, and pest control when growing plants in straight compost.
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An ideal compost to soil ratio is usually 1:2 or 1:3 depending on the plant variety.
With the right compost preparation and care, your plants can reap the benefits of compost’s nutrient-rich organic matter when added as a planting medium or soil amendment.
Can Plants Grow in Compost Only?
Can plants grow in compost only? Not nearly as well as you’d think. Compost is an irreplaceable soil amendment, but that’s just what it is – an amendment. Some of the essentials in compost are only good in small amounts. Too much of a good thing can lead to problems, such as ammonia toxicity and excessive salinity.
And while compost is rich in some nutrients and minerals, it’s surprisingly lacking in others. Much as it might go against your gut instinct, planting in pure compost could possibly result in weak or even dead plants.
Growing Plants in Pure Compost
Growing plants in pure compost can cause problems with water retention and stability as well. When mixed with topsoil, compost works wonders with water, as it allows good drainage through heavy soil while it retains water in sandy soil. Used on its own, however, compost drains quickly and promptly dries out.
Lighter than most soils, it can’t provide the stability necessary for strong root systems. It also compacts over time, which is especially bad for containers that won’t be nearly as full a few weeks after you plant in them. So while it may be tempting, planting in pure compost is not a good idea.
That’s not to say you shouldn’t plant in compost at all. Just an inch or two of good compost mixed with your existing topsoil is all your plants need.
What to Expect When You Plant Directly into Compost
FAQ
Can you plant directly in compost?
- Nutrient-rich: Compost is packed with nutrients that plants need to thrive.
- Improved soil structure: Compost can help aerate and improve soil drainage, leading to healthier root growth.
- Reduced need for fertilization: Compost acts as a natural fertilizer, reducing the need for synthetic amendments.
Do plants grow well in compost?
Compost helps plant growth by balancing soil density.
Can you grow in 100% compost?
In theory, yes, you can grow in 100% compost, at least if it’s the kind of rich, dark, crumbly compost that you might make on your own from a good variety of sources. Much of the commercially available compost tends to be more homogenous, though — “mushroom compost”, “composted manure”, “composted bark” and so forth.
How long should compost sit before planting?
- Texture and Color: Mature compost should be dark, crumbly, and soil-like.
- Smell: It should have a pleasant, earthy smell, not sour or rotten.
- Turning: Turning the compost regularly (at least every few weeks) helps speed up the decomposition process.
- Squeeze Test: A handful of compost should feel damp but not dripping wet.
- Weeds: If weeds start growing in the compost, it’s a good sign that it’s ready.
Should you plant in pure compost?
So while it may be tempting, planting in pure compost is not a good idea. That’s not to say you shouldn’t plant in compost at all. Just an inch or two of good compost mixed with your existing topsoil is all your plants need. Gardening tips, videos, info and more delivered right to your inbox!
Can you put compost down a plant?
Compost can also be put down in a thick layer over your existing soil to plant directly into. During the growing season you can also side dress any plants with compost as a part of your fertilizing schedule. Additionally, you can even make a compost tea to use as a foliar spray.
Should I use a mix of compost with garden soil?
Even with mature compost, it’s advisable to use a mix of compost with garden soil to provide a better structure for plant roots and ensure adequate drainage. When considering which plants are suitable for direct planting into compost, opt for those that benefit from rich, organic materials:
Can a no-till gardener plant directly into compost?
Many no-till gardeners successfully plant directly into compost. There are a couple of things to keep in mind though. First of all, compost is a soil amendment, not soil. Plants do need soil as well. Secondly, you need to be sure that your compost is completely finished going through the decomposition process.
Is compost good for plants?
Compost is full of nutrients, but they are not necessarily well-balanced for a plant to grow from. Remember that plants have not evolved to be planted into compost, but into soil. Boosting soil and making it rich is great, but compost is just that: a boost, an amendment, not a replacement.
Why should I add compost to my vegetable garden?
In my garden, everything gets planted in a thick layer of straight compost layered over my existing garden soil. Adding good compost to your vegetable garden will help deliver water and nutrients to your plant roots. Compost helps to build soil structure, creating an environment for water to move freely to plant roots.