Hardwood vs. Leaf Mulch

Mulch is a common gardening material. In fact, it’s just as common as soil for its versatile material base and uses. Mulch is anything that can be organically broken down over time, including leaves, twigs, lawn trimmings, and compost, along with wood chips and bark mulch which are the most common varieties. Traditional mulch tends to last the longest. Mulch is used as a booster for plants as it provides them additional nutrients as well as providing a layer of protection in more ways than one, according to the University of New Hampshire extension.

Mulch provides many benefits for vegetable gardens as it does with any kind of garden. Mulch acts like a blanket, insulating soil during harsh winters as well as protecting roots from the harsh summer sun. Mulch kills weeds by smothering their shallow roots, keeping them separate from your garden and keeping gardeners from weeding. It also invites in earthworms, prevents erosion and provides nutrients for the plants as it erodes. Mulch helps slow moisture evaporation, which means more water remains in the soil for the plant roots and less watering.

However, each vegetable garden requires specific types of mulch to survive. Should you use a hardwood mulch or a leaf mulch? There are a few ways to decide.

Hardwood Vs Leaf Mulches. Which is better?

Hardwood

Pros: 

• Hardwood mulch comes in a wide range of colors to match your home and your decorum. 
• It’s easier to rake up and till, given its size
• Some varieties have a smell that wards off bugs or pests.
• It prevents certain weeds from growing 
• This mulch lasts longer and gives you more time to relax.

Cons: 

• It can be harmful when added to soil that is constantly tilled. If tilled into the soil, hardwood will draw necessary nitrogen from the vegetables, where leaf mulch doesn’t do this.
• The pH levels of the soil can change as the mulch decays.
•  Hardwood mulch can be harmful in windy areas as it can be knocked into plants. 
• If the hardwood mulch is layered too thickly, it can crush smaller plants.

Leaf Mulch

Pros:

• Leaf mulch is beneficial during colder months. The multiple layers act as an insulator and better protect against the wind and the cold.
• Leaf mulch decays quicker, which draws in helpful organisms like earthworms
• Retains water exceptionally well
• Preferred for vegetable gardening

Cons:

• Easily blown away if not correctly positioned, hardwood is better, especially if laid more thickly and packed in.
• Leaf mulch decomposes quickly, requiring more frequent reapplication. 
• If leaf mulch is densely packed, it can kill the plant because of no sunlight, which requires more tilling to prevent them from packing too thickly.

Water retention/drainage strengths

Both hardwood mulch and leaf mulch retain and drain water to an extent. Leaf mulch is much better at retaining water. The best type of mulch for water drainage depends on the plant, but given how leaf mulch better retains water, it’s probably best to use hardwood mulch.

Heat and Cold Protection

In the winter hardwood mulch is best for an insulator as the thick layer traps heat better, especially if the hardwood mulch is a darker color. It’s better for it as the same reason it keeps weeds from growing, it insulates better. Leaf mulch is better for heat protection as the layers are looser and a bit more cool, so long as it’s tilled regularly. 

How to use either type correctly in your vegetable garden

What to choose?

Choosing the correct sizing and material quality

Everything in mulch depends on what kind of plants you’re growing and their needs. Hardwood mulch may change the pH, which is not ideal for plants like hydrangeas. Larger mulch may kill smaller plants, so if you have small plants you need a finner mulch. This requires individual research of the vegetables you wish to grow and their needs then select the mulch from there.

Consider your optimal decomposition period/timeline

Your mulch will decay faster in a hotter climate, and if you want your mulch to last longer you’ll want a chunkier, thicker mulch like hardwood mulch. This will also affect what time of year you place it down. Spring is the best time as it gives the seedlings time to sprout through the mulch, having that protective layer before the sun appears.

Measure properly according to bed size

When buying mulch you’ll have to do some math and some research. Smaller plants will only need so much mulch, and a specific amount that is important to pay attention too if you’re using the heavier bark mulch. The average amount of mulch you need is 2-3 inches, usually never more than four, so you’ll have to calculate it. You first multiply the length and width of your box, then times it by the depth of the mulch you need. Once you calculate this you’ll have to convert it to cubic feed and thus buy accordingly.

Place onto freshly cultivated soil appropriately

Before you even put down the mulch you have to cultivate the soil properly. You need to clear out any rocks or debris, and remove any of the grass if you are simply digging into the ground.  You need to have a loose soil, loosened to about 8 inches in depth so your plants have an easier time taking root. When you apply the mulch, make sure your soil is moist but not wet. When placing it you have to lay it on top and leave it alone so as not to disturb the seeds.

Use landscape fabric if needed

If you are going for a leafy compost or a thinner bark mulch, landscape fabric may be beneficial. This layer goes beneath the mulch but above the soil itself. If you are particularly worried about weeds this will be your best bet.

Finish off with light watering layer

When you’re done, lightly water the mulch to give your seeds a nice bath and help start the decaying process for your mulch to ensure optimal nutrient distribution.

Maintenance

Monitor your beds improvement over time

One of the most important things to do with mulch is to watch your plants. If your plants start to decay or wither from lack of sunlight or too much water you may have miscalculated and need to adjust the mulch according to the needs of your garden. You also might need to occasionally till them to keep them from becoming too overpacked, and this can be evident by the condition of your plants.

Careful not to create too thick a layer of use incorrect ratios

As mentioned in 1, too thick of a layer or incorrect ratios can kill your plants. You may not have even miscalculated, you may have just needed to level it better in a few spots. Mulch on average should be less than 4 inches thick, and the soil should be around 8. This all depends on what you’re planting of course but if you haven’t done your research keeping close to these measurements will be your best guess.

Alternating between both types might be beneficial

Alternatively, you may use both depending on what type of year. A layer of leaf mulch in the spring and summer may be beneficial. You can keep reapplying it or if it decays by the fall you can replace it with a layer of hardwood mulch to better keep it safe during the winter. You can even combine the two by placing a larger layer of hardwood mulch and a few scattered leaves to encourage beneficial bugs. The choice is ultimately up to you.

Adding nitrogen sources after initial setup

Nitrogen is essential for the growth and wellbeing of plants. Without it, plants will wither and turn yellow. Too much nitrogen will cause an expansion of foliar growth but at the expense of flower formation, root growth and fruit set. It’s a common myth that mulch steals nitrogen from the soil, but that’s simply not the case. If your mulch is not providing the nutrients it needs you can use all natural nitrogen supplements like manure, coffee grounds, or fertilizer to give the plants the boost they need.

Keep an eye out for pests and weed contamination

Although hardwood mulch can keep out certain pests and both can kill weeds, that doesn’t mean a few might find their way in. Weeds are weeds, they are resilient and you’ll still have to pluck them or apply weed killer depending on the variety. Pests like aphids will still be an issue, which will require bug sprays or organic solutions, so keep and eye out for both.

Regularly add more ground up material where necessary

As previously mentioned, mulch can decay and plants may need more nitrogen than the mulch is providing. When needed, add extra mulch to spots of decay or to plants you spot nitrogen deficiencies in. This will ensure the health and safety of your plants, and ensure the best possible harvest.

Manage levels through freshening techniques 

When you place down more mulch it’s essential to “fluff” it before putting down more. Mulch tends to settle and get compact. Fluffing takes a rake or tool and stirs up this packed layer, revealing more mulch than you initially thought. If you fluff it and see there is more than two inches it’s unlikely you need more. However if you fluff it and it’s still bare you can manage the levels by adding more mulch.

Remove /replace annually if the need is there

Mulch should be removed if you notice discoloration, or soil erosion. It should also be removed if it’s infected with fungi. It is unnecessary to replace it every year, but it does need to be completely replaced after 5-6 years. If your mulch is down to an inch, replacing the old mulch is essential.

Conclusion

In short, there is no winner of the hardwood or leaf mulch debate. Both have their benefits and deficits. Hardwood is hardier but can accidentally harm plants if used incorrectly. Leaf mulch is gentler, a better heat insulator but decays very quickly. Hardwood can drive away pests and leaf mulch can invite beneficial insects in. It’s all down to choice at the end of the day, same as picking your vegetables. You have smaller vegetables using leaves, larger, hardwood. Even the seasons can dictate which to use so at the end of the day you might as well do both, or at least keep the other on hand if need be.

The stopping of putting down mulch isn’t too complicated but is rather tedious. You first have to start with research. Everything you do in your garden is up to you but if you haven’t done your research you will have not only wasted your money, but your time and resources into a garden doomed to fail. You have to consider the time it will take to decompose in order to budget for more mulch and you have to measure properly according to the size of your garden bed in order to not have to make multiple trips to your local hardware store or wherever you acquire mulch from. You have to cultivate your soil before you even begin, tilling it and making sure you have enough of it in the first place. You should debate whether or not you need landscape fabric, and if you do buy it and make sure to cut it down to size and properly place it in the bed. After that you gotta water it and keep monitoring it from then on out.

Either choice is good for gardening beds, but you have to watch what you do. No matter which you choose you still have to monitor your vegetables for problems, watch the ratio’s your place down, remove and replace it annually, regularly add more material, watch out for pests and ultimately alternate between the two materials.

Ultimately the decision comes to you. However it can seem overwhelming with everything involved and if you’re a first-time gardener it’s easy to make mistakes without a guiding hand. Hawkin’s Landscape Supply can provide not only the resources to plant your garden but the knowledge as well. Located in Northwest Washington and Suburban Maryland, Hawkin’s Landscape Supply has been around since the 70’s helping new gardeners and old ones alike, keeping their gardens crisp and keeping their vegetables right. If you have any questions, be sure to give them a call and have one of their certified technicians aid you today!