10 Container Gardening Mistakes & How to Avoid Them

The Container Gardening Market Is Growing

The U.S. garden planter (pots) market is currently valued at USD 4.08 billion and is projected to reach USD 6.65 billion by 2032, growing at a CAGR of 5.6% (Yahoo! Finance).

This growth reflects rising interest in home gardening, limited outdoor space, and a shift toward more flexible, self-contained growing systems.

Why Gardeners Sometimes Struggle with Container Gardening

Container gardening looks simple. Put soil in a pot. Add a plant. Water it.

But growing in containers is very different from growing in the ground.

In a garden bed, plants have access to a large soil volume, natural drainage, and a steady supply of nutrients. In containers, everything is limited:

• Soil dries out faster.
• Nutrients wash away.
• Roots run out of space.
• Temperature swings are more extreme.

That means small mistakes have much bigger consequences.

“Most people think container gardening fails because they don’t have a green thumb. In reality, it fails because containers create a completely different growing environment. When you control space, moisture, and nutrients consistently, success becomes repeatable.” — Mark Bolt, Vice President of EarthBox^®

The good news is that most container gardening failures come down to a handful of predictable errors. Once you understand what they are and how to avoid them, growing vegetables and herbs in containers becomes far more reliable.

Here are the most common container gardening mistakes. And how you can fix them.

Mistake #1: Selecting the Wrong Gardening Container

Choosing the wrong container size leads to many problems, including poor plant growth, rootbound plants, and dry soil.

“Most container gardening problems start with the container itself. If roots do not have enough room and consistent moisture, everything else becomes harder to manage.” – Mark Bolt, VP of EarthBox^®

For example, the soil dries slowly if your planting box is too large. That leaves your plant roots in wet soil because they can’t absorb all the moisture, making them more susceptible to root rot.

Conversely, the soil dries quickly in gardening containers that are too small. And that leads to you constantly having to water your plants. By the way, clay and terracotta planters have a similar impact. Their porous nature causes the soil to dry more rapidly than a plastic planting box.

The Proper-Sized Container Gives Roots Space to Grow

You need a planter box deep and wide enough for plant roots to get sufficient growing space. The more your plant’s roots can spread in the gardening container, the more they can access moisture and essential nutrients from the soil.

Learn 5 valuable tips for selecting a planter box.

Focus on the Depth of Your Container

Ensure your planting box is at least 8 inches deep when growing vegetables. Generally, the deeper your planting box, the larger your reservoir of moist soil. Equally important, the more room your plants will have for root growth.

Eight inches of depth accommodates a variety of vegetables, including garlic, onions, lettuce, brussels sprouts, strawberries, herbs, and radishes.

Self-irrigated planters are the exception. SIP planters have a water reservoir below the planting area to provide moisture for the plants. For example, EarthBox vegetable planting boxes feature self-watering, removing some of the guesswork from container gardening.

You’ll need an even deeper gardening container (10 inches or more) for beets, broccoli, potatoes, beans, sweet corn, peas, squash, eggplants, and carrots.

Bigger is Better When It Comes to Planting Boxes

Regarding the length of your planting box, leave a planting space at least two inches wider than the plant’s diameter. If you’re going to err, err on the side of too large so that your plants have adequate space to spread.

Because plants come in all sizes, you’ll need to determine the plant's mature size and limit yourself to a number that fits comfortably in the gardening container.

There are plenty of resources online that provide placement charts for plant spacing. For instance, EarthBox offers placement charts for its planting boxes.

Mistake #2: Failing to Consider Plant Requirements

The reality is that most vegetables grow perfectly fine in gardening containers. Still, knowing which plants grow best in your climate is essential. When in doubt, talk to someone at your local garden center or utilize your local Cooperative Extension. Some container gardening companies like EarthBox also have growing guides to show you what grows best in your climate zone.

Equally important, you’ll need to place your gardening containers in an area that provides at least six hours of sunlight – most vegetables require full sun. Without appropriate sunlight, your yields will suffer.

That said, pay attention during the sweltering summer months. Consider moving your plants into a shaded area for part of the day. At the very least, pay close attention to watering needs.

Learn more about the best plants for success with container gardening.

Mistake #3: Overlooking Plant Compatibility

First, don’t overplant. Placing too many plants in a container garden stunts their growth.

Second, pay attention to companion planting. Some plants work well together and benefit each other. Others, not so much.

In some cases, one plant type may produce biochemicals that inhibit the growth of another plant type. For example, beans don’t work well with members of the onion family. However, they do work well with carrots.

In other instances, one plant may be flavored by another. For example, herbs like rosemary and basil can impact the flavor of cucumbers.

Garlic also impacts some plants negatively. For example, when planted with lettuce, it produces chemicals that cause the lettuce to wilt.

You can learn more about companion planting here.

Mistake #4: Over or Underwatering Plants in Your Container Garden

Here’s where many novice gardening enthusiasts mess up. And typically, the results are the same whether you water too much or too little – your plants wilt and die. Or if they survive, your yields are poor.

Underwatering leads to dry soil and stunted growth. Over-watering leads to root rot and other concerns.

Remember that water is lost more quickly from garden containers than from the ground. And, as mentioned, some containers are naturally porous, allowing moisture to evaporate from the sides. By lining terracotta planters or using non-porous planting boxes, you can reduce that concern.

Water also evaporates from the soil surface in containers. So use mulch or gravel to limit the evaporation and minimize your watering requirements.

Checking for Moisture in Your Planting Box

You can check the soil’s moisture by inserting your finger into it. If it feels dry, it’s time to water.

When you water, focus on saturating the soil. Less frequent waterings that soak the soil are better than more frequent ones that only dampen the soil. Check for water coming out of the drainage holes to know when you’ve saturated the soil.

Drainage Holes Are a Must

Speaking of drainage holes, they’re essential. Without drainage holes, water accumulates in the soil. Eventually, it will lead to root rot. If your planting box doesn’t have drainage holes, create some.

You have a couple of solutions if you aren’t sure when to water. One is a moisture meter. The other is a self-irrigated container for gardening.

Mistake #5: Using Poor Quality Soil

Garden soil is too dense for containers. It compacts easily, drains poorly, and suffocates plant roots.

Some folks grab a shovel, scoop up some dirt from somewhere in their yard, and use it for their containers. That’s a disaster. The soil will clump and suffocate your plants.

“Soil quality matters more in containers than in the ground. Once nutrients are gone or drainage breaks down, your plants have nowhere else to recover from.” – Mark Bolt, VP of EarthBox^®

You want to use soil that drains well while holding nutrients and providing oxygen to your plants. Focus on these three essentials for the container soil:

1. The soil should be light and fluffy.
2. It should include peat moss, which helps with water retention.
3. Soil should include perlite or vermiculite, which creates air space.

You can amend the soil with compost, dried manure, slow-release fertilizer, or other essential nutrients to get your plants off to a good start.

You can also save yourself some time by getting a planting kit. For example, EarthBox offers a custom-blended potting mix specifically designed for planting boxes. It also includes fertilizer.

Get more insights into the best soil for container gardening.

Mistake #6: Failing to Feed Your Plants Regularly

Even if you mix composted manure into your soil before planting, that fertilizer will only last a few weeks. In addition to your plants consuming the nutrients, some will drain from the container.

It’s essential to fertilize your vegetable planting boxes every two to four weeks. Some plants require even more frequent feeding. For example, fruiting plants like tomatoes and peppers benefit from weekly feeding. You can even dilute the fertilizer and feed them every day.

Your two best options for fertilizer are granular or liquid fertilizer. The former has slow-release granules that absorb into the soil when you water.

You mix liquid fertilizer with water. Then pour it into the planter. You can also spray some on the plant’s foliage, as they will absorb the fertilizer.

A word of caution. If you spray fertilizer on the plant’s leaves, do it in the morning. That way, the plants can dry out before cooler night temperatures hit. Wet foliage invites fungal diseases. That’s why it’s also best to water in the morning.

Don’t Forget These Initials – N, P, K

They stand for nitrogen, phosphorus, and potassium. Each is critical for your plant’s health. When first planting, using a balanced fertilizer with equal parts N-P-K is fine. You’ll often see notation like 10-10-10 to represent the percentage of each nutrient.

After planting, focus on incorporating nutrients essential to your growing vegetables. For example, leafy vegetables like lettuce require nitrogen.

Fruiting plants like tomatoes and peppers like phosphorus, while root crops like carrots and potatoes thrive on potassium.

This is another reason to focus on companion planting. In addition, you’ll benefit from having plants that need the exact fertilizer requirements.

Mistake #7: Failing to Thin and Support Plants

Keep your plants within the required space. There’s nothing wrong with pruning or thinning plants. However, your plants will grow better and face fewer disease concerns because they’ll have better airflow.

In addition to thinning plants, you’ll also want to support plants that tend to sprawl or produce heavy fruits: cucumbers, tomatoes, eggplants, etc. They can quickly take over a space.

Concerns without Staking

Moreover, fruiting plants can come into contact with the ground without staking, leading to spoilage or pest concerns. You also run the risk of the plant’s stems cracking.

It’s also best to consider staking when you initially plant. Otherwise, you’ll have to force the plant’s stems to fit the trellis. That leads to breakage, which can cause you to lose budding fruits and cut production.

Mistake #8: No Drainage or Poor Drainage

Drainage problems are one of the fastest ways to kill container plants.

When excess water can’t escape, roots sit in soggy soil. That deprives them of oxygen and creates the perfect conditions for root rot, fungal disease, and nutrient lockout.

Even containers that claim to be “self-watering” still need a controlled way to drain excess water or regulate moisture levels.

If your planting box doesn’t have drainage holes, you should create them. If it does, make sure they aren’t blocked by compacted soil or debris.

A simple test: water your container until moisture begins to drain from the bottom. If nothing comes out, you have a drainage problem.

Mistake #9: Ignoring Seasonal and Temperature Changes

Containers heat up and cool down faster than the ground.

In summer, dark containers in direct sunlight can overheat, stressing roots and slowing growth. In spring and fall, sudden temperature drops can damage or kill sensitive plants.

“Containers amplify temperature extremes, especially black pots. When you adjust placement as seasons change, you give plants a much more stable growing environment.” – Mark Bolt, VP of EarthBox^®

Many gardeners forget that they can move containers. Shifting pots into partial shade during heat waves or bringing them closer to a building for warmth during cold snaps can make a significant difference.

To make the job easier, you can invest in a raised garden bed stand with wheels. The raised height makes gardening more comfortable, while the wheels let you move your bed to avoid the hot midday sun or stormy conditions.

As seasons change, it is also important to remove spent plants and rotate in crops suited for cooler or warmer weather.

Mistake #10: Failing to Refresh or Recondition Container Soil

Many gardeners reuse the same container soil season after season without improving it.

Over time, container soil breaks down. It becomes compacted, loses structure, drains poorly, and holds fewer nutrients. Even if you fertilize regularly, old soil can’t support healthy root growth as well as fresh or reconditioned soil can.

Used container soil can also accumulate salts from fertilizer and minerals from tap water. These salts interfere with nutrient uptake, leading to weak growth and leaf burn.

“Container soil is not a one-and-done resource. It needs refreshed yearly to maintain drainage, structure, and nutrient balance.” – Mark Bolt, VP of EarthBox^®

How to Refresh Your Container Soil

At the start of each growing season, remove spent roots and refresh your container soil. You can replace a portion of the old mix with fresh potting soil or amend it with compost to restore structure and nutrients.

If your soil feels heavy, crusted, or drains slowly, it’s time to recondition or replace it.

Refreshing your soil each season helps maintain drainage, improves oxygen flow, and gives plants a healthier foundation to grow.

EarthBox Helps Avoid Container Gardening Mistakes

One of the best ways to avoid container gardening mistakes is by using EarthBox products. We’ve developed complete gardening systems to help ensure your success. It’s why we’ve been a top-rated and trusted provider since 1994.

“Container gardening works best when you remove as many variables as possible. A consistent system makes success repeatable.” – Mark Bolt, VP of EarthBox^®

Commercial farmers developed our planting boxes. They’re tested and proven in the lab. So you get superior results whether you have a green thumb or not.

Our maintenance-free system controls soil conditions and watering, eliminating the guesswork. As a result, you’ll get double the yields of a conventional garden. So whether you’re planting tomatoes, herbs, vegetables, or strawberries, you’ll get superior yields.