How to Use Straw Mulch in Your Garden

Choosing the right mulch is a big deal for gardeners. Depending on what you want to grow, wood chip mulch is a good option, or maybe grass clippings are best. But for most working in a raised bed vegetable garden, straw mulch is one of the best mulches out there. 

Straw has many benefits. It promotes water retention and prevents soil compaction. It keeps plant roots healthy and is beloved in the organic gardening world. So if root health and irrigation are an issue for you, maybe straw is the answer.

In your home garden, you have to know which organic matter is best for mulch, and which type is most appropriate for your situation. So before you spread more mulch on your garden bed, let’s cover some tips for using straw as a mulching medium. 

What Is Straw Mulch?

Interestingly, there is more than one type in the “straw” category. Each of these has its place in varying garden beds. To figure out which of these straws is the best garden mulch for you, let’s examine each variety. 

Straw Mulch

These are the remnants of cereal and grain crops. Straw differs from hay only slightly because it’s the remaining hollow stalks of wheat, barley, or rye. 

Straw typically does not contain seeds. This prevents the need for pulling weeds constantly in the growing season. It’s a great way to help you do a lot less work in the ground and gives your yard splashes of beautiful golden color. 

You can usually find large bags of straw at nearby hardware and tractor supply stores. You may also find straw in bales at variable costs. 

Certified Weed Free Straw Mulch

It is likely that you’ll obtain straw that isn’t weed-free if buying it in a standard bale or bag. If you’re concerned about weed seeds in your mulch, search for a certified weed-free straw instead.

Just like regular straw, these are cereal and grass crops that have been harvested, but these are steam-treated to remove weed seeds that make gardening laborious. This type of mulch is great for your garden or for composting. 

We’re particularly fond of straw that undergoes an all-natural process that filters out wheat and weed seeds, such as GardenStraw. The finer sizes it’s been chopped and split into make the application incredibly easy, and it’s virtually dust-free.

Some livestock supply companies also produce weed-free straw, but it may include wheat or barley seeds. This means you may end up with unexpected wheat or barley plants in your garden.

Hay Mulch

Unless you’re doing active composting, hay mulch might be the least desirable straw out there because it contains the most seeds from weeds and invasive plants compared to the other aforementioned mulch types. Pure hay is often used to feed livestock and is sourced from farmers and ranchers who have a surplus on hand. 

Although it breaks down easily, mulching with hay can unintentionally steal nutrients from your garden because of the quantities of weed seeds that may be contained therein. As weeds grow, they pull nutrients away from other plants. 

If you don’t mind pulling weeds often, hay might be an acceptable option for your garden. If weeding time doesn’t appeal to you, try one of the other mulch materials mentioned here. 

Alfalfa Mulch

This is a specific cereal crop that is steam treated to remove seed heads. Unlike basic straw and hay, alfalfa mulch starts out green. As these mulches break down they turn golden and provide a wealth of nutrients into the soil, especially nitrogen, which is an essential part of healthy garden soil. After all, alfalfa meal is used as a nitrogen supplement in organic fertilizers!

There are a couple of downsides to alfalfa. First, it’s expensive. Although organic materials like this are great for early root development, some of the nitrogen needed in the vegetable garden could evaporate into the air if it is not applied properly. But overall, it’s a great garden mulch you can find in most garden centers. 

Pine Straw

This is fallen, dried pine needles that act just as other mulches do in garden beds. If you’re into regenerative agriculture, and you live near pine trees, this organic material is great for garden mulch. For those who live near pine trees, it’s practically free. Otherwise, it’s about the same price as straw. 

It’s a great garden mulch because it doesn’t compact as it breaks down, so it won’t create a mulch layer that causes a water table to form, choking out your plants. Pine straw doesn’t contain seeds either so you won’t have to worry about weeds in your mulch or in your garden. 

Some have expressed concern about whether pine straw is acidic. If it has turned brown and naturally fallen from the tree, it’s essentially pH neutral. Green pine needles are still mildly acidic, but the dry brown ones have lost most of that acidity.

Pros And Cons Of Straw Mulch

Here we’ll get into some of the intricacies of straw mulching and how it can help or hurt the plants in your garden. Often disadvantages occur with improper selection and application of mulch. Gardeners would do well to consider which layer of mulch will be best for their soil. 

Benefits

Each type of mulch mentioned above will help your soil retain moisture. That means you won’t need to water as much and you can save some time and money. Established plants in healthy soil, watered by drip line, and covered in mulch are in an ideal environment. 

This is especially the case with certified weed-free mulches. Here, there are fewer weeds to worry about. Without invasive weeds, these mulches help reduce soil erosion. Topsoil loss is something a lot of regenerative gardeners are hoping to combat. Mulch is a huge part of that fight to preserve topsoil. 

Mulches also keep disease down in your garden. As they break down, they not only add nutrient content to the soil but also prevent the proliferation of bacteria and fungi that may be lying fallow in the soil. Concurrently, mulches keep the planting soil within the bed and prevent runoff. They make gardens look great too, adding a splash of color here and there.  

Depending on the source of your mulches, they can cost anywhere from nothing to under $100 for the first application. Often straw mulches can come from sources where they’re no longer desired. Find a farmer who wants to offload some straw and you’re set. 

Finally, in hot climates, the light color of a straw mulch can help reflect extra heat away from the soil. This maintains the right temperature for seed germination without allowing the soil to bake in the sun. Similarly, it protects soil in cooler climates by acting as a blanket over the soil’s surface, keeping it warmer than it would be if exposed.

Drawbacks

Because straw decomposes into the soil quickly, especially compared to wood chips, it may not retain its appealing golden appearance for as long as some would like. Although they’re still regulating soil temperature, you’ll need to spread a mulch of this kind at least once per growing season. 

A hay bale (or bales) can be heavy and hard to take apart, and they might have weeds within them. Some of them may even promote soil-borne diseases if they are applied too thickly or thinly. But even a great job of laying mulch can be completely offset by constant weeding around your plants. 

If you’re interested in more expensive alfalfa or hay mulches, consider a good cost-benefit analysis before spending money. Sometimes larger gardens would do just as well with a free source of mulch rather than something that will cost a lot of money to incorporate in composting or garden soil. 

Probably the least common problem with straw mulches is they could contain insecticides and herbicides that kill off good nutrients present in your soil as they break down. Consider the source before purchasing. Generally, this is not a major issue, but it’s still possible.

What you’re looking for is something that doesn’t contain harmful chemicals, weeds, or pests. If you’re unsure, do some research into your straw source first. 

Where To Use Straw Mulch

There are appropriate times to mulch your garden, and inappropriate times too. Here are a few tips on different ways to apply.

Seed Starting 

You won’t want to mulch the soil right when you direct seed because it could choke out seedlings or provide too much moisture, preventing sprouts altogether. 

Instead, wait until your seeds sprout and mature to the point where they are high enough above the soil so that a thin layer of mulch won’t keep in too much moisture. In that same vein, it’s appropriate to mulch around mature, already-established plants. 

Do not apply straw in a thick layer around newer plants. While your compost heap appreciates a foot deep layer, your garden prefers about three to six inches of spread mulch in the planting area. 

Instead of mounding straw up against each plant, make sure there is a small empty area around the base of your plants instead. This prevents choked roots and allows moisture to flow directly to the root system of the plant. It also prevents fungus and bacteria that occur in overly moist garden conditions. 

Composting With Straw

Straw is great for mulching, and it’s great in composting too. Use it to cover your pile in a layer thick enough to cover green matter, and you’re set for nutrient-rich compost which you can apply to your garden in upcoming seasons. 

You can even use a bale of straw to create the frame for a compost pile. Simply later each bale on the ground in a square or rectangular shape. Then add your compost materials within. As the compost breaks down, so does the straw. There’s no need for wire, tumblers, or piles in this method. 

Use the rich humus compost when you sprout vegetables for the upcoming season. You’ll find gardening with this compost very rewarding, especially if the straw you sourced is free of weed seeds. One way you’ll know the straw is doing its thing is your pile will offset steam in the winter. That’s a good sign things are going as planned. 

Attract Earthworms

One of the best tips I’ve received in my gardening adventures was to incorporate some straw (free of chemicals, of course) into the soil to bring the boys to the yard… the boys being earthworms. I’ve found that adding just a little bit to my beds produces rich soil earthworms love. 

When I’m planting in later seasons, I’ll see earthworms as I dig. Earthworms are always a sign of even healthier soil to come because they leave behind worm castings which provide essential and micronutrients important in vegetable gardening.  

Straw Pathways

One cool way to use excess straw is to put it in the walkways between your garden beds. Not only does this add some contrast and an element of design to your garden, but it also prevents weeds. Instead of constantly pulling weeds from the garden border, you’ll suppress them with straw. 

Just pull a large handful from your bale, and shake it around walkways. Use a rake to fine-tune the design, and add layers as needed. 

Frequently Asked Questions