he importance of organic mulch is frequently underrated and misunderstood. However, mulch plays a critical role in Arizona gardens, especially during water shortages and record high temperatures. If you aren't all that familiar with mulch and how it can help your garden, keep reading. By the end of this article, you should have a firm grasp on mulching and can look forward to a lush, vibrant garden.
In simple terms, mulch is anything that is placed over a garden bed that helps to reduce evaporation, insulate the soil surface against heat, and prevent weeds from growing.
You can use all types of mulches in the desert, with many gardeners using everything from straw and wood chips to rocks and living mulches (which is not always a bad idea in the desert).
Let's explore more of what makes a good mulch, and how it can benefit your garden and improve your soil.
Take a look at your plants during summer. Are they thriving despite the scorching temperatures? Or do they look sad, wilted and in need of some attention. If they look like they are struggling now, just wait until the next heatwave hits.
Whether you live in the desert Southwest or make your home in a more temperate climate, plants can suffer during hot, cloudless days.
You can easily tell if your plants are struggling with the heat. Just take a stroll through your garden during the hottest part of the day. If you see signs of wilting, yellowing, or browning leaves, then your plants may be suffering from heat stress.
Mulch can come to the rescue of a heat-stressed garden, so you can enjoy a vibrant garden full of beautiful, vibrant plant life, or increase your harvest yields if you are an avid veggie gardener.
In the dry Southwest, water conservation is always a high priority, and there's no better way than to cover the soil with an extra layer. However, mulch does more than provide a ground cover.
Fluctuations in soil temperature can cause adverse reactions in plants. Mulching the soil helps to regulate the temperatures and even out the wild swings of the mercury.
It's important to note that many artificial mulches like plastic can raise the soil's temperature, while organic mulches like straw will lower the overall soil temperature. Mulches that raise soil temperature may benefit cooler parts of the world to extend the growing season. They are generally impractical in a hot desert environment like most of Arizona, however.
Thick layers of mulch prevent the sun's rays from reaching the surface. Any seeds that are present are unable to germinate, and young plants are prevented from growing. This effect has the benefit of preventing weed growth and reducing the amount of labor required in the garden. Young plants and seedlings that you do want to grow can have small areas of mulch cleared away. Once their roots are established, you can move the mulch back in.
As we stated earlier, mulch is an excellent way to conserve water in the garden, which is especially useful in dry areas like the Southwest. The extra layer between the sun and the soil blocks evaporation, but the mulch also helps with water retention and reduces the need for excessive watering.
Mulches break down and add essential nutrients and organic matter to the soil, including humic and fulvic acid. Humic acid binds to plant roots to help them take in water and nutrients. If you are a veggie gardener, humic acid is essential for growing plants with optimal nutrition levels.
Fulvic acid combines minerals present in the soil and converts them into organic matter that the plants can access more efficiently. Soils with adequate amounts of fulvic acid are also able to retain more water and increase water infiltration.
Mulch can also lower soil alkalinity and encourage earthworms and other beneficial arthropods to take up residence in your garden. Soil erosion and compaction from walking and heavy rain are also significantly reduced with the addition of mulch.
Feeder roots in a mulched garden will develop much closer to the soil's surface because of the improved conditions and available nutrients. The growth of deeper roots will be curbed because the moisture the plant needs sits much closer to the surface.
Just about anything can be used for mulch, but you should consider each of their benefits and drawbacks to help you decide which will work best in your garden.
At first thought, a living mulch may seem like it would use too many resources like water and reduce the availability of other nutrients. However, Arizona gardeners have been using living mulches to smother weeds and cool the soil on hot summer days. Here are a couple of favorite living mulches you can consider using yourself.
Arizona Blue Sage is drought, heat, and cold tolerant and attracts butterflies, honeybees, and hummingbirds to your garden.
You can enjoy hot pink flowers from summer to fall on a backdrop of dense green foliage. This is a heat-tolerant plant that prefers full sun to partial shade and is attractive to hummingbirds and butterflies.
The above two plants are excellent examples of living mulches, but they will require supplemental watering if rainfall is scarce.
Veggie gardens can be attractive, but a good yield is the most critical factor for gardeners. Therefore, the mulch you choose for your vegetable gardens doesn't have to factor heavily on the ornamental side of things. Vegetables will prefer a mulch that breaks down and adds nutrients to the soil, so straw or hay are good choices.
Straw and hay are also the cheapest options in mulches, which is essential when your reason for growing vegetables is to save a little on the grocery bill. Don't neglect free mulches when they are available. Leaves also break down and add nutrients to the soil, as does sawdust, wood chips, and grass clippings.
If you do a bit of online research, you can often find wet hay that a farmer may want to offload for cheap. Make sure you check bales for seed heads, or you could be harvesting wheat in a few weeks. Store bags of leaves you collect in the fall to use for next year's planting. Tree chipping companies will also happily give you their wood chips for free or at a nominal cost.
Avoid grass clippings that are treated with herbicides. If treated clippings come into contact with your plants, it won't bode well for them. Also, the chemicals can leach into your soil and cause you all sorts of problems.
While vegetables will thrive in mulches of hay and straw that are worked into the soil, you might prefer something a little more attractive and less rural for a landscaped garden. Trees will prefer a surface level mulch like wood chips, which will also look more appealing than hay or straw.
Mulch that is only 2 to 3 inches deep is necessary to get good results. If you go deeper than that, then rainfall may not penetrate through to the soil layer. Wood chip mulches reduce evaporation and help the soil retain moisture. You should also be careful to stop the mulch from bunching up against the trunk as constant moisture may cause rot.
The desert has a natural covering of stones, so it seems logical to use rock mulches in your landscaped desert garden.
Rock mulches are nothing more than a layer of stones placed over the surface and may be appropriate for gardens featuring desert natives. However, take care where you use rock mulches as they tend to reflect light and heat and will create hot spots in your garden. The water demands of your plants will also increase.
You should also consider that rock mulches do not break down to add valuable nutrients to the soil. In general, if your Arizona garden features mostly desert natives, then you may not need any mulching at all. Native plants are already perfectly adapted to the prevailing conditions.
Avoid gravel mulches in your desert garden. Gravel will radiate heat into the soil and boil off any life, making it difficult to grow anything. Local wildlife like butterflies, bees, and hummingbirds will also avoid the intense hot spots in your garden. There's also the problem of the radiated heat contributing to the already significant urban heat during summer.
Any areas where you intend to mulch should be cleared of all weeds, grass, and leaves. Lay down the mulch until it's about three inches thick. Clear a few inches of mulch when planting new plants or around tree trunks to avoid any chance of rot from moisture. You will notice your organic mulches (straw and hay in particular) thinning and disappearing over the year. You can be sure that the mulch is decomposing and adding vital nutrients to your soil, but it will need to be replenished for the next crop of plants.
References:
[1] https://www.thespectrum.com/story/life/features/mesquite/2015/05/07/mulch-plays-vital-role-desert-gardens/70972152/
[2] http://viragrow.blogspot.com/2017/07/mulch-is-magic-and-desert-soils.html
[3] https://www.southwestvictorygardens.com/blog/how-to-improve-desert-soils
[4] https://iamcountryside.com/growing/best-mulch-to-prevent-weeds/
[5] https://www.thespectrum.com/story/life/features/mesquite/2015/05/07/mulch-plays-vital-role-desert-gardens/70972152/
[6] https://www.southwestvictorygardens.com/blog/how-to-improve-desert-soils
[7] https://www.azplantlady.com/tag/mulch
[8] https://link.springer.com/chapter/10.1007/978-3-030-22301-4_6
[9] https://www.goveganic.net/article124.html
[10] https://www.ecofarmingdaily.com/build-soil/humus/humic-acid/
[11] https://www.advancednutrients.com/articles/humic-fulvic-acid-for-plants/
[12] https://www.fbts.com/xeric-choices/four-top-drought-resistant-perennials-for-dry-shade.html
[13] https://landscapearizona.com/blog/mulch-for-cooler-soil-and-better-plants/
