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Growing vegetables in containers is an ideal way to start your own vegetable garden if you don’t have actual gardening space because you live in an apartment or are just not on the ground floor. Containers can be used to grow vegetables both indoors and outdoors. This article focuses on how to start an outdoor container vegetable garden on a balcony, terrace, or rooftop, but most of the information given will be applicable to any type of container vegetable garden
If you have space to start an in-ground vegetable garden or a raised bed vegetable garden, you may first want to find out the pros and cons of growing vegetables in containers, before fully committing yourself.
Most vegetables grow well in containers, as long as the container used is large enough. A few types of vegetables that are tough but not impossible to grow in containers are pumpkins and corn. Pumpkin plants cover a large ground area and need to be grown in containers that have a volume of at least 10 gallons, making them a bit too bulky for balconies, terraces, and other areas where container gardens are usually placed. For corn, although you can easily grow 4 corn plants can be grown in a 12-inch wide container, you may need at least 16 plants grown together to have them properly pollinated.
Choosing the best place for your container garden
Your container vegetable garden should be placed in an area where the needs of your plants will be met as best as possible. This means that it should be a place that gets:
- Enough sunlight
You can grow vegetable plants in an area that gets at least 2-4 hours of sunlight, but you will be limited to growing leafy greens and a few other types. The ideal amount of sunlight for a vegetable garden is 6-8 hours of sunlight, to be able to grow almost all vegetables, including sun-loving tomatoes and peppers.
In taller buildings shading can be an issue, particularly if there are other tall or taller buildings located very close by. The amount of shade or sunlight in a given area can change throughout the day. So, its important that you observe your chosen space throughout the day to make sure that it’s getting enough sunlight.
- But not too much sunlight
Just as much as not getting enough sunlight can be a problem, getting too much sunlight can also be a problem for vegetable gardens on taller buildings in warmer regions or during warmer weather. This is because vegetable plants and fruiting vegetables can get ‘sun-burned’, resulting in a loss of color and vegetables that aren’t edible.
A location that gets only morning sun or evening sun would be the best without too much afternoon sun, which is usually the harshest. In case you aren’t able to find a cooler area, another alternative is to install shading cloth covers above your container vegetable garden.
- Proper air circulation
Vegetable plants need proper air circulation for photosynthesis and disease prevention.
Photosynthesis is the process that plants use to make food which is eventually deposited in the vegetables that we harvest. Good air circulation helps plants take in carbon dioxide from the air and release oxygen as part of the process of photosynthesis.
Good air circulation also helps plants release excess water into the atmosphere, which helps prevent diseases from affecting the plant.
Areas on balconies and terraces that have stagnant air, which is quite common near walls, should be avoided.
- Near a water source
Locating your container vegetable garden as near as possible to a water source will make it more likely that you will water your vegetable plants regularly, especially since container vegetables will usually need to be watered once a day.
Selecting suitable containers for your vegetable plants
This is probably the most important step in starting your container vegetable garden because the containers that you use will have to hold everything from soil to water that your plants will need. The main factors to consider when choosing containers to grow vegetables in is that they should be:
- Large enough
If the containers that you choose to grow vegetables in are too small, your plants and their roots will be stunted, unhealthy, and as a result, will be easily affected by pests and diseases.
Each type of vegetable plant has a minimum container size that it can grow in, which mainly depends on the maximum size of the plant and its roots. For smaller plants like lettuce, peas, onions, and garlic, a container with a capacity of two gallons or more with a depth of at least four to six inches would do. To grow larger plants, like tomatoes, eggplant, cucumbers, and peppers, you will need containers with a capacity of at least 5 gallons and that is at least 12 to 16 inches deep.
Recommended container sizes for commonly grown vegetables and herbs
- Have proper drainage
Nothing can ruin a container vegetable garden worse than insufficient drainage. The containers that you use should have at least 4 holes with a diameter of at least 1 cm at the bottom. This is so that any excess water and along with it excess salt could easily drain out while watering. You can further adjust the drainage by adding the most suitable soil or soilless mix but proper container drainage has to be in place before.
- Be able to keep moisture
Container vegetable garden plants only have access to the moisture that is in the limited amount of soil or other media in the container. This makes keeping in moisture very important for the plant to continue its usual internal processes between waterings.
Although you may feel like you should use terracotta pots because it’s more natural since you are growing organic vegetables, terracotta is very bad at retaining moisture. In addition, terra cotta pots are on the heavier side and a large number of pots may be too heavy for certain balconies and other areas.
You can also consider using wooden pellets and other wooden containers, but treated wood leaches harmful chemicals and untreated wood has to be of a good type and quality for it to be long-lasting.
Plastic pots are the best for container vegetables since they not only keep in moisture but can also keep in heat and are lightweight. If you are worried if it’s safe to grow food in plastic containers, we’ll see about that next.
- Be safe to grow food in
According to Livestrong.com, it’s safe to grow your food in certain types of food-grade plastic containers. The signs that indicate the type of plastic are usually found at the bottom of the container.
- High-density polyethylene (HDPE; sign: number 2 in a triangle) – used for milk jugs, water bottles, trash bags, and some buckets
- Low-density polyethylene (LDPE; sign: number 4 in a triangle) – used to make milk jugs, water bottles, and trash bags
- Polypropylene (PP; sign: number 5 in a triangle) – a strong plastic used to make caps and lids
- Polylactic acid (PLA) – a newer type of bio-based (wheat, corn, rice derived) and compostable plastic used in 3D printing
Plant pots available for sale at garden centers are usually made from HDPE, LDPE, or PP, and are safe to grow food in. Despite being safe, neither of these types of plastic is specifically made for outdoor use and should be replaced as soon as you see signs of the plastic breaking down.
Plants are also frequently grown in reused plastic containers made out of Polyethylene terephthalate (PET; sign: number 1 in a triangle), which is a clear, tough plastic usually used to make water, juice, and soda bottles. PET bottles are fine for ornamental plants but are not suitable for vegetables and other food plants since they leach out chemicals. Alternatively, you can safely reuse milk jugs, yogurt cups (for seed starting), and other containers made out of PP to grow your food in.
Using the best soil or soilless mix for your container plants
As a general rule, you should never just add garden soil alone into containers, as over time it will compact and throttle the roots of your vegetable plants.
The easiest way to fill your containers is to use a commercially available potting soil mix. Potting soil mixes may or may not contain actual soil, organic material (e.g. cocopeat, compost, rice hulls, bone meal, and worm castings), as well as inorganic material (e.g. sand, limestone, and perlite). Some of the ingredients will add nutrients to the soil over time while others increase drainage and improve the structure of the mix.
Alternatively, if you are able to get any of these ingredients for free or for cheap in your area, you can create your own soil or soilless mixes. A few of my favorite easy-to-make container vegetable substrate mixes are given below.
Each type of mix is more suitable for different types of vegetable plants or climatic conditions. You can use these as a base and change them as needed and based on the materials available.
- Soilless mix for vegetables that prefer loamy soil (suitable for tomatoes, eggplant, and okra under dry conditions; tomato containers containing this mix may need to be brought under cover when it rains heavily)
- 1 part matured compost to 2 parts cocopeat
- Soilless mix for vegetables that need well-draining loams (suitable for chili and peppers, or tomatoes grown in rainy conditions)
- 1 part matured compost, 1 part compost, and 1 part sand
- Sandy mix for vegetables that prefer sandy loams (e.g. gourd vegetables)
- 1 part sand to 2 parts matured compost
Small amounts of perlite, worm castings, gypsum, and other amendments can be added to each of these mixes, as available.
Starting your vegetable plants
You can start your container vegetable garden plants from seeds or you can buy or grow your own seedlings. Starting from seeds is usually cheaper than buying seedlings. Buying seedlings will help you gain time if you have a shorter growing season and is easier since the hard work of seed starting has already been done.
Most types of vegetables can be grown as seedlings and then transplanted. Root vegetables, such as carrots and beetroot should always be grown directly from seeds since transplanting will damage their roots. Corn, gourd vegetables, such as squash and cucumbers, as well as legumes, are better off if grown directly from seeds, but can be transplanted with care, especially when they are a lot smaller.
Vegetable plants should be grown directly from seed in the pots and then thinned or the correct number of plants that match the size of the container can be transplanted. Seedlings are usually ready for transplanting once they have grown at least a pair of true leaves (after the first set of leaves, known as the ‘Cotyledons’, which is actually the growth of the seed covering). Seedlings can be transplanted a bit later provided that they have enough space and nutrients in their original container but long before they start to flower.
Read more: Seeds vs. seedlings
Caring for your container vegetable garden
Now that you have started your container vegetable garden, you need to care for it properly to get a good harvest. Container vegetable vegetables are rather care-intensive because everything that they need has to be in or around the container that they are in.
- Watering:
Container vegetable gardens usually should be watered at least once a day. Early in the morning is best but early in the evening works fine as well. It’s best to water so that a little water runs out of the container, so that excess salts that have built up can be carried away.
You may have to water your container plants as much as twice a day if the weather gets really warm. Similarly, container plants can easily get overwatered during heavy rains or continuous rain. If this happens, you should stop watering your plants and bring your plants into a covered area, if possible. If it rains only slightly, you can continue with your usual watering schedule.
More information on watering container vegetables
- Fertilizing:
The best fertilizer to use as a beginner is compost. This is because matured compost has a balance of nutrients that the plant needs and releases the nutrients slowly. You can add a layer of compost on top of the soil or medium of your container plants once a month to once every two-three months as needed.
Since compost takes time to mature, you will probably need to buy compost from a reliable source the first few times. You can start making your own compost at the same time that you start your vegetable garden just from your kitchen scraps and other garden waste right next to your container vegetable garden. You can buy a suitable compost bin or can simply make your own quite easily.
- Weeding:
Weeds aren’t usually an issue in container vegetables kept in built-up areas, especially if you use commercially available potting soil or other soilless mediums. If an occasional weed pops up, all you’d need to do is to pull it out before it grows further and starts competing with your vegetable plants.
- Mulching:
You can mulch your container vegetable plants using organic mulches, such as dried grass, to help control temperature fluctuations and retain moisture. A very thin layer of mulch that is replaced as needed is best for container plants.
In case your container plants become overwatered during heavy rains or by accident, you should immediately remove any mulch until the soil can dry out. Soil that is too wet becomes a breeding ground for soil-borne diseases.
- Troubleshooting:
Container vegetable gardens are easily affected by pests and diseases because they are easily affected by over or under-watering and nutrient deficiencies. Keeping your plants well watered and fertilized will definitely help minimize problems but you should also take at least 5 minutes a day to have a close look at your plants and their health. This can be at the same time that you water them or during your rest time during the cooler part of the day.
If you do identify an issue, especially if you suspect a pest, it’s always best to move affected plants away from other plants, especially of the same type or same plant family.
Common pests that affect container vegetable plants are aphids (and ants), spider mites, mealy bugs, whiteflies, nematodes, and leaf miners.
Nutrient deficiencies and diseases are tougher to identify because they can be easily confused with issues caused by over-watering or under-watering and are usually related. If the leaves of your plants are turning yellow/brown or dropping, it’s best to first eliminate and slightly change your watering schedule or move the plant into the shade or more sunlight, if possible, to see if it helps.
Reusing containers
Once you have grown and harvested your vegetables, you can easily reuse your containers for the next season after a little bit of preparation.
- Disinfecting the medium:
Disinfection is very important if your plants had been affected by a soil-borne disease or pests that spend at least some of their life cycle in the soil.
There are a few methods of disinfecting your soil. If it’s still warm enough at the end of your growing season or at the start of the next, you can use soil solarization to disinfect your container medium at barely no cost. Other methods include steaming or heating in an oven or microwave.
If you find it difficult to disinfect, it would be best to get rid of the soil or medium and start a new.
- Adding more compost, nutrients, and other structural components: by the end of the season, your container medium would have lost quite a bit of nutrient and structure. You will have to mix in compost, nutrients, and other structural components before reusing the medium.
The containers can be reused as long as they don’t show any signs of breakage or cracking. You can simply remove the existing medium and wash the container under running water.
As you can see, it’s not too hard to start and grow a container vegetable garden. You just need to set it up as best as possible at the beginning and then keep a close watch on your plants, and act as soon as the need arises, so that you grow healthy and productive vegetable plants.
