adding soil to potted plants

10 Common Container Gardening Mistakes

What is more cheerful in your outdoor space than pots of planted flowers? Not many types of decor are easier to make happen, either. And even if you’re not new to container gardening, everyone can enjoy learning a new trick or two. Avoid the 10 most common container gardening mistakes.

Filling a Container in the Wrong Place

Ever tried to lift a large garden container filled with dirt and plants? It can be overwhelmingly heavy. When using a large or unwieldy container, place your pot where it will live and then fill it–you’ll save your back!

Also, if you know you are planting shallow-rooted plants in a very large container, fill the bottom third with empty plastic bottles, and then place plastic screening over them. You can also use a product called ​”Better Than Rocks” to take up space. Fillers make your container lighter (and less expensive) because you don’t need as much potting soil.

Pot stands with wheels can also come in incredibly handy if you end up having to move a heavy pot into partial shade during the hottest part of summer.

Selecting Plants With Different Requirements

All the plants in one container should share the same sun, soil, and water requirements. Find out this information from your seed packets or plant labels and plan the containers accordingly.

Starving the Plants

Most potting mix has very few of the nutrients that plants require to be healthy, and they’re either used up quickly by the plants or are washed out with repeated watering. So you will need to add food to the soil. There are many fertilizer products on the market; just remember to choose what you need based on the plant type. Flowering plants have different nutrient needs than vegetables and herbs.

Fertilizing container gardens regularly is key. You can start with a slow-release fertilizer mixed in with your potting soil when you put the plants into the pots, and then add a diluted, liquid fertilizer, such as fish emulsion, every couple of weeks. Organic or all-natural fertilizers will improve the soil as they break down and don’t run the risk of building up chemicals or salts.

Overwatering Your Plants

To avoid overwatering your container gardens, use containers that have drainage holes–lots of them.   Also, be aware of the moisture requirements for your plants and then follow them. Before you water, check if your soil is moist. To do this, put your finger into the soil up to your second knuckle. If the soil at your fingertip feels dry, water the plant.

If you do overwater, the leaves may turn yellow and fall off, or your plants may get limp. If your soil is too wet, move the container to a dry, breezy spot until it dries out. If you have the room, you can also move your container garden into a garage or sheltered spot to dry it out, particularly if the weather continues to be wet.

Underwatering Your Plants

Most container gardens need watering at least once a day in the heat of the summer. Many, especially hanging planters or small containers, need watering even more often because there is less soil to hold moisture. When you water, really soak your plants–if you give them just a sip, only the top layer of soil will get wet. Water until you see it coming out of the bottom of the pot.

Many people use water crystals in the soil that absorb water and then slowly release it when the soil dries out, but they are expensive. More than one study has shown that they aren’t effective, so skip buying those.

If your plants do dry out completely, don’t despair; even the most pathetic, limp plant might revive with a good drink. If the container is small enough, submerge the whole thing in a bucket of water until the air bubbles subside. For a large container, take a skewer or stick and gently poke holes deep into the soil to allow water to reach the plant roots. Then, water generously.

Having an Awkward Plant-to-Pot Ratio

Consider the proportions of your plants to their container. A large container stuffed with short plants can look stunted. If you need a rule of (green) thumb, try to have at least one plant that is as tall as the container. Also, plants that spill over the sides soften the edges and add texture and interest.

Don’t put too much in one pot; remember, the plants will grow bigger as the season goes on. Plants crowded in smaller pots grow more slowly than those that have room to stretch out.

Buying Sick and Weakly Plants

Buying plants at a reputable local nursery is a good place to start in your quest for healthy plants. You have a greater chance of getting plants that are disease and pest free and well cared for at a nursery that starts its own plants than at a big box store that buys from distributors. At a nursery, you can also get a wealth of information and advice from knowledgeable staff. Don’t be afraid to ask someone to help you pick out a good plant.

If you can’t resist the prices at a big box store, buy the plants on or close to the day they’re delivered. Ask an employee on which day the new plant stock arrives. Delivery is usually the same day every week.​

Make notes as to which plants came from where; if you end up buying a tomato plant with blight from a big box store, you can pull it and the others that came from that store, hopefully before the disease seriously affects others in the garden.

Fearing Pruning

When your container gardens start looking leggy or ragged, don’t be afraid to cut them back. You may want to put them in an out-of-the-way spot until they rebound, but chances are they’ll come back healthier and happier with a good haircut.

Living With Ick

After you’ve tried everything a plant still looks dreadful, cut your losses and toss it on the compost pile or in the trash. If only one plant in a container garden doesn’t make it, just pull out that plant and replace it for an instant visual improvement in the container garden.

Having Unrealistic Expectations

Before you plant your containers, evaluate your time available for their care. Do you travel a lot during the summer? If so, either use self-watering containers or an automatic drip irrigation system, enlist some help to keep your plants healthy and alive while you’re gone, or purchase plants that don’t need a lot of water.

Garden how you live. Are you casual or formal? Some people like neat, well-planned, formal containers. Others enjoy plants that spill and sprawl over the edges as they like, planted in a multitude of colors rather than in a particular design scheme.

However your container garden ends up, it’s really a low-risk outdoor decor technique—there’s a lot of room for error. Pick plants that grab your eye, and experiment with combinations and placement. Whatever your lifestyle or personality, you can plant containers that will give you joy and bring beauty to your surroundings.

Even if you're not new to container gardening, you can still learn new tricks. Avoid the ten most common container gardening mistakes.

Soil in Containers Should Be a Good Mix

Garden soil doesn’t offer enough air, water, or nutrients to container-grown plants. Fortunately, it’s easy to amend.

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I work hard to ensure that the soil in my garden is the best I can give my plants, and they reward me with robust health. Yet that same good soil if transferred to a container would cause the plants in it to languish. That’s because garden soil doesn’t offer enough air, water, or nutrients to a plant growing in a container. Potting soils are specifically formulated to overcome these limitations.

Potting soil needs to drain well but still hold moisture

One of the most important things a potting soil needs to do is provide roots access to air by letting water drain away from them. In the ground, the soil is usually deep enough to let excess water drain beyond root zones. In pots, however, water tends to accumulate at the bottom, despite drainage holes. The smaller the pore spaces of the soil in the pot, the higher that water layer will reach. Larger pores, formed by adding mineral aggregates to potting soils, readily admit water into the soil, then carry it through the medium and out the bottom. Then, all those large, empty spaces can fill with air.

Perlite, vermiculite, calcined clay (kitty litter), and sand are the mineral aggregates most commonly used in potting soils. Perlite and vermiculite are lightweight volcanic rocks naturally filled with air. I prefer perlite over the others because it does not decompose with time nor lose its aerating ability if the potting mix is compressed. Vermiculite is a valuable additive because it prevents some nutrients from leaching away, and it even provides a bit of potassium and magnesium.

A potting mix also must have ingredients that help it retain moisture. This is where organic materials—usually peat moss, sphagnum moss, or coir—come in. They cling to some of the water that the aggregates are helping to drain. Organic materials also hold on to nutrients that might otherwise wash away.

In addition to peat moss, vermiculite, and perlite, commercial mixes often contain sawdust or various grades of shredded bark. Lime may be added to help balance the acidity of the peat moss, and a small dose of fertilizer can often make up for the lack of nutrients.

Adding compost or garden soil can be beneficial

Most gardeners make potting soil by combining perlite or vemiculite with peat or sphagnum moss. Two other organic materials that you could add to your potting mix are leaf mold and compost, which offer a wide spectrum of nutrients.

Adding some garden soil to a homemade potting mix contributes bulk while buffering against pH changes and nutrient deficiencies. The reason that garden soil is rarely added to commercial mixes is because of the difficulty in obtaining a steady supply that is consistent in quality and free of toxins such as herbicide residues.

Customize your mix to suit your plants

Soilless potting mixes are relatively free of living organisms, but mixes made with soil or compost are not. Some gardeners talk about “sterilizing” their potting mixes by baking them in the oven to rid the soil of harmful organisms, limiting the hazards of damping-off and other diseases. What I hope they mean is that they “pasteurize” their mixes. Heating homemade potting mixes to sterilizing temperatures wipes out all living things, beneficial and detrimental, leaving a clean slate for possible invasion of pathogens and causing nutritional problems such as ammonia toxicity. Pasteurization, which occurs at lower temperatures, kills only a fraction of the organisms. The best way to pasteurize your soil is to put it in a baking pan with a potato embedded in the soil. Bake it at 350°F for about 45 minutes. When the potato is cooked, the potting mix is ready.

I don’t pasteurize my potting mix. I rely, instead, on healthy container-gardening practices such as timely watering, good air circulation, and adequate light to avoid disease problems. Beneficial microorganisms in compost and garden soil also help fend off pests.

Lee’s recipe for homemade potting soil

I’ve found that making my own potting soil produces better results than commercial mixes and eliminates the need to monitor my containers’ nutrient and pH levels. With plenty of good soil in my backyard, I have no trouble making this traditional potting medium. It features a mixed bag of ingredients, but I figure that plants, like humans, benefit from a varied diet. This mix can support plants for a year or two without additional fertilization.

Mix 2 gallons each of:
* peat moss
* perlite
* compost
* garden soil

with 1/2 cup each of:
* dolomitic limestone
* soybean meal
* greensand
* rock phosphate
* kelp powder

I place a 1/2-inch mesh screen over my garden cart and sift the peat moss, compost, and garden soil to remove any large particles. I then add the remaining ingredients and turn the materials over repeatedly with a shovel, adding water if the mix seems dry. After a few incantations, the stuff is ready to work its magic on everything from my tomato seedlings to my weeping fig.

Make your own soilless mix

Years ago, Cornell University scientists came up with a formula for a soilless potting mix, which forms the basis for many commercial potting mixes on the market today. By following this recipe, you can easily replicate what is sold in bags at the garden center.

* 1 bushel peat moss
* 1 bushel perlite or vermiculite
* 1/2 pound dolomitic limestone
* 1 pound 5-10-5 fertilizer
* 1 1/2 ounces 20% superphosphate fertilizer

Mix the ingredients thoroughly. The mix is initially hard to wet, so moisten it as you stir it. This saves the trouble of doing so each time you remove some for use.

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Garden soil doesn't offer enough air, water, or nutrients to container-grown plants. Fortunately, it's easy to amend.