The soil in your raised garden beds has had a lot of work to do over the summer. Even with regular fertilizer application, summer crops do a very good job of taking all that they can to produce vegetables and fruit.

“Soil will diminish in nutrient levels and organic matter over time because nutrients are being used by plants,” says Cassey Anderson, Colorado State University extension specialist. And that’s only the primary reason why soil declines after a whole summer’s use.

We chatted with gardening and horticulture experts to learn more about why soil declines, what causes it to compact, and what can happen if you don’t amend it throughout the fall before winter starts. They also provided insights into the importance of adding mulch, cover crops and compost to improve your raised bed soil before winter. 

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Ready to fix your raised bed soil ahead of the official start of winter? Read on for the steps you can take right now—you can thank us later. 

The Reasons Soil Declines and Loses Nutrients, According to Experts

While this may seem obvious, one of the main reasons your raised bed soil declines and loses nutrients over time is because your plants use them. Moreover, Randy Forst, extension educator, consumer Horticulture and master gardener coordinator within the University of Arkansas, Division of Agriculture and Beth R. Bolles, a horticulture educator at UF IFAS Extension Escambia County, explain that the soil can settle and lead to the decomposition of its organic matter as your plants grow (and are watered), causing the nutrients to deplete. 

That said, nutrient loss isn’t the only factor that can cause your raised bed soil to decline. “It can be overworked with tillage and lose aggregation, which can lead to compaction and loss of soil organic matter,” says Mina Vescera, Cornell Cooperative Extension of Suffolk County Extension educator and nursery/landscape specialist. “Some soil nutrients can leach from the soil, needing to be replenished with either compost or fertilizers.” 

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What Can Happen to Your Soil If You Don’t Amend It in Fall?

If you don’t amend your raised bed soil in the fall, you increase your chances of permanent nutrient loss that your plants need for proper growth. While we touched on this earlier, soil compaction is one of the main issues that can harm the health of your raised bed soil.  

How to Amend Your Soil Before Winter, According to Experts

The good news is there are several actions you can take right now to amend your soil before winter. 

1. Compost

Even though you might be tempted to add compost as soon as possible, Leandro O. Vieira II, Ph.D., assistant professor and soil fertility specialist at Scott Research and Extension Center at Louisiana State University AgCenter, recommends performing a soil test first. In addition to adding nutrients and drainage, adding organic matter improves aeration and drainage.

You do need to be mindful of how much compost you’re applying, as adding too much can be counterproductive. Adding too much runs the risk of creating a nutrient imbalance in your soil.

Compost will also help you keep your raised bed soil hydrated. “It also improves the soil’s ability to hold moisture while still allowing excess water to drain, which is a nice combination for raised beds,” explains Tabar Gifford, partnership Cultivator and master gardener at American Meadows and High Country Gardens.

2. Cover Crops

Cover crops can be another way to keep your plants from losing nutrients ahead of winter. They can benefit gardens as they help the soil maintain its structure and keep soil microorganisms as healthy as possible. 

While cover crops are beneficial, it’s important to choose the right ones. “Cover crops can help improve soil organic matter, can provide nitrogen (if selecting legume varieties) and can act as a living mulch that can reduce weed pressure,” says Anderson. That said, Vieira notes that selecting those adapted to your location is a best practice for the best outcomes. 

3. Mulch

Mulch is another substance that you can use to protect your raised bed soil from becoming compacted in the winter with rain and snow. “Any natural bio-degradable mulch can be used. (straw, cotton seed hulls, shredded paper, shredded wood mulch, untreated grass clippings, rice hulls and even compost),” says Forst. “They readily break down and build up the soil.” Overall, mulch works to provide protection and therefore should be taken seriously. 

Sources: 

• Leandro O. Vieira II, Ph.D., assistant professor and soil fertility specialist at Scott Research and Extension Center at  Louisiana State University AgCenter
• Cassey Anderson, Colorado State University extension specialist 
• Mina Vescera, Cornell Cooperative Extension of Suffolk County Extension educator and nursery/landscape specialist
• Randy Forst, extension educator, consumer Horticulture and master gardener coordinator within the University of Arkansas, Division of Agriculture
• Beth R. Bolles, a horticulture educator at UF IFAS Extension Escambia County
• Tabar Gifford, partnership Cultivator and master gardener at American Meadows and High Country Gardens