10 Tips for Successfully Growing Vegetables in Containers

Lettuce Container Garden in a Reusable Grocery Bag.
Photo © Kerry Michaels

Know How Much Sun

One of the most important things for success with growing vegetables is to know how much sun they will get. While there are some edibles that grow just fine in shade, many need full sun. In my experience, almost everyone overestimates how much direct sun an area gets. Sun exposure can be challenging to figure out, because the sun moves across the sky during the growing season. While an area may get sun all day during the early spring months, by the time July and August roll around, trees, buildings, even your own house or fence may obstruct the sun, creating deep shade for a significant portion of the day.

The best way to figure out how much sun an area gets is to either use a sun calculator or visually check your area. If you are checking visually, you will need a watch and a piece of paper and a day when you are going to be home and able to look at your chosen area every hour or two.

Starting in the morning at around 7, look at your planting spot to see how much sun it is getting. Is it full-on, unobstructed sun? Is it shade? Dappled shade? Write this down and throughout the day, every hour or two take a look and write it down again. It is worth doing this every four weeks during the growing season to make sure your vegetables are getting enough sun. To make matters more complicated, you may need to check this every couple of years. Trees can grow and buildings get additions or appear which can obstruct your sunlight.

Many vegetables will need 7 hours of full sun. And that isn’t late afternoon, that is mid day sun. So 8 AM to 3 PM is perfect. You may have some wiggle room here, but not much (say 10-4 might work too). However, there’s a caveat here. If you live in a hot climate, you may need to give some veggies afternoon shade. Once the heat hits the high 90’s some vegetables can become stressed.

So check you’re your specific vegetables for sun requirements and follow them.  Root vegetables and greens usually require less sun.

Full Sun Vegetables:

Part Sun Vegetables
Salad Greens

  • Growing Potatoes in Containers
  • Growing Arugula
  • Growing Lettuce in a Reusable Grocery Bag
  • Growing Peas in Containers

Garlic Just Harvested - © kerry michaels

Container Grown Garlic.
© kerry michaels

Choose Your Vegetables Wisely

As container gardeners, we usually have space constraints that other gardeners don’t have to worry about. So assuming space is at a premium, how do you decide what to grow? Part of the way I decide is figuring out which vegetables will give me the most bang for my buck and space. I don’t grow cabbage, because that takes up a lot of space and is usually pretty inexpensive at the store. I do grow lots of mesclun and baby greens because they are easy and fast to grow, and ridiculously expensive to buy. Also, you can squeeze a lot of greens into each pot. They are also beautiful.

Then there is taste. I grow tons of tomatoes because their taste far surpasses anything I can buy at the store. I find that cherry tomatoes are easiest to grow in pots, but I like the challenge, so also grow large tomatoes as well. Also because they taste so good warmed by the sun, right off the vine. Potatoes are relatively inexpensive to buy in the store, but like tomatoes, they are another vegetable that tastes so much better homegrown that they are worth the space and care they need.

I grow a huge number of herbs. Again, they are expensive to buy, and they are also beautiful. I also like having them accessible—grabbing handfuls, without having to go to the store.

I also grow edible flowers and fancy vegetables I wouldn’t be able to find, like fairy tale eggplant and blue potatoes.

List of Some Beautiful Edibles

Eggplant - © kerry michaels

Growing Eggplant.
© kerry michaels

Feed Your Plants

Because potting soil doesn’t have many nutrients for your plants, you need to add those nutrients and, depending on the type of fertilizer you use, you will usually replenish them as the growing season progresses.

When I first plant my vegetables, I mix an organic, slow-release granular fertilizer into the potting soil, making sure that it is distributed throughout the pot. This can take some mixing if you are using a large pot, but you don’t want all the nutrients to be at the top of the soil, you want it to also be near the roots.

I then feed the plants an organic, diluted, liquid fertilizer every few weeks following the directions for quantity. I have used a combination fish and seaweed emulsion, though it does smell pretty bad. There are other alternatives that are less stinky. Check at your local nursery.

Espoma Gro-Tone

Nature’s Source
Terracycle Plant Foods

Chard - (c) kerry michaels

Container of Chard.
(c) kerry michaels

Water Just Enough

Depending on the type of pot or container you are using, you may have to water several times a day, so make sure you have an easy access to water. Shlepping big, heavy watering cans gets old quickly, so the closer your pot is to a hose or spigot, the better and the more likely you are to water your plants.

While you don’t want to water too little watering too much is just as deadly to plants—it just is a slower death. The best way to see if your plants need water is to stick your finger, up to the second knuckle into the soil of your pot. If it is moist, down by your finger tip, wait to water. If it’s dry add water. While it is better to water in the morning, if your soil is really dry—whatever time of day or night, give those plants a drink.

Assuming your pots have sufficient drainage (which is so critical, I have written a whole article on it, see link below), when you do water, keep going until you see the water coming out of the bottom of the container. That way you will know that the roots have access to the moisture and that you have thoroughly wet the soil. It can seem like a tremendous amount of water, but until it comes out the bottom, don’t stop. If the soil is really dry, it may take lots of water to re-hydrate. I see many people just giving their plants a sip of water, which means it only permeates the first few inches of soil, which doesn’t do the plant much good, especially if it has deep roots, which many vegetables do.

For some vegetables, particularly tomatoes, a consistent level of moisture is critical. If you let the soil dry out and then water, tomatoes will crack. Also, many vegetables can experience blossom end rot from inconsistent watering.

Using self-watering containers is a great way to give vegetables consistent water and they make it virtually impossible to overwater. Setting up a drip irrigation system is also a smart way to make sure your plants are getting enough water, even if you are away on vacation.

Tips on Watering Containers

Earthbox garden on dock - Photograph © Kerry Michaels

Photograph © Kerry Michaels

Choose the Right Pot

While anything can be turned into a container, for vegetables, bigger is often better. While you can probably grow some greens in a thimble, but to keep that tiny amount of soil moist, you would have to water it about once an hour on a sunny day. You also wouldn’t get much lettuce. The more soil capacity your pot or container has, the more and longer it will retain water and that is critical for healthy vegetables.

Some materials lend themselves better than others for growing vegetables. A big terra cotta is gorgeous, but porous, so will dry out faster than many other materials. I sometimes line terra cotta with bubble wrap or a plastic bag so the soil will retain water longer. Food grade plastic pots can be great looking, colorful and good for veggies. Even 5 gallon buckets, that are sometimes given away by stores and restaurants, can be great for growing tomatoes, peppers or beans. Just make sure to drill enough holes in the bottom to insure good drainage.

I’m a huge fan of fabric pots. They come in a wide range of sizes, from tiny to raised bed sized. They can be decorative or functional, fold up for easy storage in the winter and plants seem to love them.

Cement and hypertufa pots are fine, as long as they are large enough. Be careful with tires and other rubber as there may be a health hazard from the leaching of harmful chemicals. Metal pots, feed troughs or buckets also look great, but heat up quickly in the sun. You can line them with bubble wrap or fabric to protect the plants roots from direct contact with what can be searingly hot metal, but the soil will also heat up, and depending on your climate, might fry your vegetables.

I’m a huge fan of self-watering containers like Earthboxes.

Here are 5 Great Containers For Vegetables

peas on potting soil - (c)

Potting Soil with Pea Seeds.

Use Good Potting Mix

Whatever you do, don’t fill your pots with dirt from your lawn or garden. You need to buy or make a medium that will stay somewhat fluffy and won’t compact. Most potting mixes are a combination of peat (though there are some serious environmental concerns with peat), or coir, vermiculite or perlite and pine bark. Some have a slow release fertilizer mixed in and some have “wetting agents,” or water crystals. I use a good quality, organic potting soil for my vegetables. My favorites are Coast of Maine , Organic Mechanics , and Black Gold. I tried Miracle Gro organic potting soil and didn’t like it. Though inexpensive, it was kind of mucky, with large chunks of bark and not a good texture. It also smelled kind of funny. If it’s all you can find, I would mix it with another brand of lighter soil, like Pro Mix. I also like the potting mixes from Gardeners Supply which is lightweight and has a great texture.

container gardening picture of green tomato - Photograph (c) Kerry Michaels

Green Zebra Tomato.
Photograph (c) Kerry Michaels

Know When To Harvest

This may sound obvious, but when you are growing purple tomatoes and black peppers, it can be a little confusing. Tomatoes generally should be just a hint soft when squeezed, but the real tip-off is when the skin gets glossy. Cucumbers are harder to tell and it depends on what variety you are growing. It’s a good idea to keep a journal so you can look up how big they are supposed to be when ripe. The same with eggplant and many other vegetables. While the plant tags may give you days until maturity, you can’t totally count on that because the weather and where you are growing can impact those dates.

seedlings - (c) Kerry Michaels

(c) Kerry Michaels

Growing Seeds or Seedlings

I live in a cold climate and don’t have all that many growing days (days between frosts). Unless I start seeds indoors, there are many vegetables I don’t have enough days in my season to grow. Conversely, there are some herbs and vegetables that don’t like to be started inside and transplanted.

Generally, quick growing greens and some edible flowers are easy to grow from seed in your containers. However, tender seedlings can be critter bait, so you may have to protect them from chipmunks, groundhogs and other pests.

Before you plant your seeds, find out how many days your growing season is by checking your frost dates. Then look at a seed packet to see if you have enough growing days until harvest.

Put Your Pot Near a Water Source

If you are growing edibles, you will need access to water. The closer you place your pots to a water source, the easier it will be for you to water your plants. During the heat of the summer, particularly if you live in a dry and or windy climate, you may have to water more than once a day. If you have to shlep a large watering can long distances, it is a huge disincentive to keeping your plants well hydrated and therefore healthy/alive.

A lightweight hose, that doesn’t kink, with a good watering head is very helpful. A good, large, well-balanced watering can is the next best option. Making it easier to give your plants the water they will need to thrive, should be considered as you plan your gardens.

Start Small

I know many people who have decided to grow vegetables with a vengeance. They start way too many pots and then are frustrated and overwhelmed with the amount of watering, tending and care that plants need.

The good news is that you can get tremendous pleasure out of one pot of salad greens and lots of tomatoes from a single plant. There is a huge learning curve to growing plants, so starting out small — with just a few pots or a raised bed, can be a way to see if you like it–not everyone does.


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