5 Garden Myths

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The most effective way to water is to fully drench the soil at planting time. Don’t water again until the soil starts to dry out.
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Soil pH levels can largely influence the growth rate of a variety of transplanted plants, from the tiniest berry bush to the largest trees.
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Landscaped trees with mulch in a new housing development.
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Common pests which hinder tomato production include slugs, aphids, and whiteflies.

Every hobby I’ve ever undertaken had one thing in common: The information presented by the so-called experts was only partially correct. I’ve found that gardening is no different.

Many of these garden myths started a long time ago, and have been handed down from generation to generation. Each person believes their gardening mentor’s advice and in turn passes that information along to other new gardeners. The web has worsened the progression of gardening myths by allowing anyone with a keyboard and monitor to claim they’re an expert.

Social media is full of garden myths, and in this article, I’ll discuss five of them and explain why they’re untrue. In the process, you’ll be introduced to new information about plants and their environments, and armed with this basic knowledge, you’ll gain a better understanding of your garden. 

Myth 1: Water New Plants Every Day

Plants that are newly planted need a lot of water because their root systems are almost always damaged during planting, especially if they’re divided or moved. The most common advice for new plants is to keep them well-watered. Many people interpret this to mean they should be watered every day. This isn’t the case and is a good way to kill a plant.

A loss of roots means that the plant can’t take in enough water to support the top greenery, which results in wilting leaves. The key is for soil to have a balanced moisture content. Keeping the soil moist will reduce wilting and allow the roots of new plants to grow.

When water is added to soil, it seeps down and outward, spreading in a semicircular pattern. As it moves, it fills all of the small openings in the soil, and it’s absorbed by organic matter. The soil will stay wet until the water is either used up by roots or it evaporates.

Ideal soil is 25 percent water and 25 percent air. Too much water forces the air out, which causes roots to die. This is exactly what happens when a gardener waters too frequently. Before they know it, the plant is dead.

The advice to water daily is almost never correct, even in hot climates. The most effective way to water is to fully drench the soil at planting time. Don’t water again until the soil starts to dry out.

How will you know when it’s getting dry? Test it using one of your most reliable senses: touch. Dip your fingertips into the soil until you reach the second knuckle, and if the soil feels moist, don’t water yet. Instead, water only when the soil starts to dry.

Also, avoid watering on a schedule. The frequency of watering should change all season long and depend on the plant, soil type, temperature, humidity, and variety of mulch used. 

Myth 2: Peat Moss Acidifies Soil

There are several different types of soil, all of which vary by region and environment. Your soil may have a significant amount of sand or clay, and it may contain minerals from degraded rock. Taking your type of garden soil into account is important because the soil that’s available to you will determine which plants have the best chance for growth.

Many vegetables prefer slightly acidic soil, while other desirable plants, such as rhododendrons, azaleas, and blueberries, demand higher acidic soil for healthy growth. Because peat moss is acidic many believe the addition of peat moss will acidify soil. As a result, a common recommendation for gardeners with alkaline soil is to add peat moss. This seems to make sense, but does it actually work? If it does, how long does the change in pH last?

I carried out an experiment on my blog, www.GardenMyths.com, to answer these specific questions. I began the process by creating several different mixtures of native soil and Canadian sphagnum peat moss. I measured the changes in pH over several weeks, as seen in the “Peat Moss Acidity” line graph.

 Peat moss is clearly acidic with a pH of about 5.5, with 7.0 being the pH neutral point. The five different mixtures of soil and peat moss showed a range of pH depending on the amount of peat moss in the mixture. However, the acidifying effect of peat moss was lost very quickly. After only one day, the soil samples all had an alkaline pH. After one week, the pH of all samples containing soil were still the same.

Keep in mind that this was one test, with one kind of soil. This particular soil is alkaline because of the presence of limestone commonly present in this native soil, which quickly neutralizes any attempt to acidify the soil. In this type of soil mixture, peat moss doesn’t acidify the soil. The same can be expected for most alkaline soils. Peat moss may have an acidifying effect on very sandy soil because such soil contains less buffering capability.

Myth 3: Compost Is The Best Mulch

While there are many types of recommended mulching options, deciding which mulch is best for your garden can be difficult. Mulch is used as the added top layer of a garden bed to help with common problems, such as soil moisture and weed control. Two mulch options, compost and wood chips, are widely considered gardener favorites.

So which form of mulch is better, compost or wood chips? A research study by Bryant C. Scharenbroch and Gary W. Watson compared both to fertilizer. They looked at growing trees in compacted urban soil — the kind you would find in a new home-development project. The “Soil Component” table and “Overall Tree and Root Weight” graph show what they found.

Both compost and wood chips, used as mulch, reduced compaction (soil density), increased organic matter, and added nutrients to the soil.

Compost was better at adding organic matter, but it dramatically increased the level of phosphorus and potassium. Too much compost can increase these to toxic levels, hampering the growing efforts of organic matter.

Both compost and wood chips increased the pH, which also contradicts the commonly held belief that compost makes soil more acidic.

How did the trees grow with these various treatments? Fertilizer and compost each improved growth more than watering alone, but wood chips produced the best growth.

Myth 4: Wood Chips Deplete Nitrogen

While using wood chip mulch in garden beds is a common practice, many people resist it because they believe wood chips rob soil of nitrogen. Microbes found in soil need a balance of nitrogen and carbon to decompose organic matter. As a result of this, many believe because wood contains very little nitrogen, microbes need to get the nitrogen from the soil to decompose the wood chips.

It’s true that microbes take nitrogen from the soil, but microbes are microscopic. They can only remove nitrogen from a fraction of an inch of the soil touching the wood. More importantly, this does not cause depletion of nitrogen at the level where roots grow. The results from the study, represented in the “Soil Component” table, show that instead of a decrease in nitrogen levels, there was an increase in nitrogen when using either compost and wood chip mulch.

Myth 5: Always Remove Suckers

Tomato suckers are the side branches that form at the point where leaves join the main stem. If left on the plant, they’ll become secondary stems and will produce fruit.

Suckers don’t need to be removed. A tomato plant will grow and produce well if you leave all the suckers on the plant — but there are some good reasons why you might want to remove them.

There are three basic ways to grow a tomato plant. The first is to simply plant and let nature take action, in which case the plant will form side branches and tend to sprawl along the ground. The second option is to plant and let nature nurture but maintain the plant inside a wire cage. This promotes the tomato plant’s growth by keeping the fruit off the ground and making it easier to pick. The third option is to prune the plant to a single main stem and tie it to a stake. Each of these methods offer some advantages, as shown in the “Tomato Production” table.

Pruning suckers will reduce the overall production and total weight of a single plant. Plants pruned to single canes can be planted closer together so that there are more per square yard. If you measure productivity on an area basis, productivity is about the same for suckered and unsuckered tomato plants.

A pruned tomato plant will focus more energy on the development of those few fruit stems left behind, resulting in larger fruits. The other benefit of pruning is that it causes tomatoes to mature earlier, and this can be a big benefit when gardening in colder climates.

The disease potential is higher for plants with suckers because their leaves tend to be crowded. This reduces air circulation and makes it easy for disease to spread. Removing suckers also keeps leaves off the ground, making it harder for pests like slugs to find the tomato plant fruits.

Unsuckered tomato plants are less likely to have problems with blossom end rot and cracking, but this can usually be prevented in the single-stem method with proper watering.

I’ve described three methods for growing tomatoes, but you can use hybrids of these methods to produce better tomato plants. With both the cage method and the single-stem method, you can leave the first few suckers attached to the stem to make side branches and then prune all of the remaining suckers. In climates with longer growing seasons, you can also take the early suckers, root them and then plant them to increase the number of plants.

Robert Pavlis is a plantaholic and Master Gardener who’s been growing in southern Ontario for more than 30 years. A background in biochemistry has helped him sleuth out various gardening facts, the findings of which he promotes on his website www.GardenMyths.com.

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