Growing radishes in containers for continual harvest

I like growing radishes in containers as it is a fast growing and easy to care for root vegetable ideally suited to be grown in staggered phases for continual harvest.

Radishes are cool temperature vegetables and prefer a temperature around 10-18 degrees Celsius (50-65 Fahrenheit). 

I start radishes in containers from February through October.

Tip: Try growing radishes and other fast growing vegetables and herbs like lettuce, spinach, arugula (rocket) and dill to have easy access to greens for your household. Plant the seeds in rows next to slower growing vegetables like carrots and parsnips to make good use of your available growing space.

If you are planning to plant several batches of radishes in the same spot you will need to add compost or liquid fertilizer between batches.

Growing radishes – a proven method

Plant 20-50 seeds every two weeks starting in February to have continual harvest of radishes from March through November. 

My recommendation is to mix it up with other fast growing vegetables and herbs. You could for example plant one row of radishes and complement them with greens like Swiss chard, corn salad, spinach, lettuce or arugula (rocket).  

Ideally, plant radishes during the shoulder seasons to avoid the hottest months of the year. Even when you are growing radishes in containers you will find that it is difficult to get radishes to grow well in warmer temperatures.

Radishes grown during the hotter periods have a tendency to use energy for foliage growth and then bolt and set flowers early. This is of course not ideal as we want the plant to use its energy on root growth over green leaves and foliage.

Did you now that radishes belong to the Brassicaceae (mustard or cabbage) family and are related to kale, broccoli, horseradish [1] and other cole crops.

Growing radishes in hot temperatures

You can grow radishes in containers in the midst of summer, even though radishes are a cool season crop.

This is on course one of the main benefits of container gardening radishes – we can be more flexible.

To grow radish during the hotter months try shielding the plant from direct sunlight using 30% – 50% shade covers. But even with covers, the hot weather can cause the plant to mature faster and bolt.

Shade covers often use a percentage to indicate how much light the shade cover will block. We use 30% to 50% for our vegetables when environmental factors and conditions call for it. 

The solution is to plan where to locate your container gardens. I plant radishes in containers during the hotter months and place the containers in a couple spots in our garden where there is more shade.

Follow these simple rules and you too will have an urban container garden bringing fresh vegetables to your table for every meal.

Do I need a vegetable garden to harvest homegrown radishes?

You do not need a vegetable garden to grow radishes successfully. We have had bumper harvests planting radishes in containers, raised garden beds, pots and even garden soil bags.

But choose your container or pot wisely. Radishes do not spread out but still need space for growth and root production. And if you crowd root vegetables you will end up with a smaller sized crop. Give you radishes space to grow and you will harvest plump and nice looking radish roots.

Also, if you use garden soil bags to grow radishes, make sure you choose a small root crop variety. Stay away from the longer and cylinder type varieties like the daikon radishes. 

But generally speaking, space is not a problem. There are plenty of other different radish varieties to choose from. You are sure to find a radish variety giving you the colour, shape, taste and form you are looking for.

The importance of potting soil

It is always important to use quality potting soil when growing herbs and vegetables.

And this is in many ways especially true when you grow root vegetables like parsnips, horseradish, carrots, turnips and, of course, radishes.

You can buy a good quality potting mix soil or mix your own potting soil.

Radishes grow well in a compost rich, sandy, fertile potting soil that drains well. You also want a soil that is free from stones and other hard, large objects that may interfere with root growth.

Using a well draining soil is key as radishes will suffer root rot if growing in a constantly wet soil.

Check your seed packet but most varieties of radishes prefer a slightly acidic to neutral potting soil (6,5-7,0 pH).

Grow radishes in containers from seeds

The radish plant grows from a tiny seed. Start your radish seeds directly in the pot or container where they will grow. There is no advantage or benefit to starting or planting radishes in starter pots indoors.

Radishes prefer half shade but will tolerate full sun as long as you keep the soil moist.

Make sure you use a a well-draining, fertile, compost rich and sandy soil. The soil needs to be kept moist and using mulch like grass clippings can be helpful.

1. Planting radish seeds (5 steps)

1. Draw a 1 cm (⅓ inch) deep line in the soil using a stick, dibble or your finger.

2. Water thoroughly.

3. Place radish seeds in the soil leaving about 3 centimeters (1 inch) between the seeds. If you are planting several rows of radishes allow for 15 centimeters (6 inches) of space between the rows. 

3. Cover radish seeds with soil when planted. 

4. Water the planted radish seeds gently using a watering can with a rose (like a shower head) . If you water too hard you may remove the soil and expose the seeds.

5. Cover area with a protective mesh or shade cover to repel harmful insects, pests and bugs.

2. Waiting for radish seeds to germinate and sprout

Now we wait. Radish seeds germinate in 1-2 weeks. But often, seeds will start to germinate in as little as 4-5 days and you can soon thereafter see first leaves sprout.

Most of the varieties of radish seeds you buy for your garden will produce mature radish plants in 20-30 days.

Some varieties may however take as long as 70 days to mature and be ready for harvest.  Read the seed packet before you buy seeds.

3. Caring for your radish plants

You sow seeds and wait for first leaves to sprout. Then, all of a sudden you realise that you have too many young seedlings. Do not worry. This is a happy problem.

Radish greens are a delicacy – especially the young and green leaves.

Use sharp garden scissors to thin out the weaker plants and make sure to wash the radish leaves before adding them to your next table salad.

Radish plants do not like to dry out and need plenty of water to develop that fresh peppery flavor and crispy texture we all look for.

We look for half shade when we grow radishes in containers. Growing radishes in full sun and hot temperatures calls for automatic drip irrigation to stay on top of watering .

It is important to keep the soil moist when you grow radishes in containers. Mulching the container soil with for example grass clippings, straw or hay is a great way to protect the plants from soil borne pathogens while helping to keep the soil moist for longer.

After about 2 weeks you can add more organic materials like compost or aged manure but be careful not to add too much nitrogen by mistake. Nitrogen promotes leafy growth and you have to remember that you want the growth to happen below the ground.

Before adding any type of vegetable fertilizer you need to look at what is already given to the plants. Everything from grass clippings to slow release fertilizers add up and you do not want to overfertilize your seedlings and plants.

4. Radish pests and diseases

Growing radishes in containers you are by no means immune to pests and diseases. Some of the more common pests and diseases include flea beetles [2] aphids, downy mildew, cutworms, Alternaria blight and white rust [3].

Early detection is always key with any type of pest and disease. We use a Neem oil and water spray mixture to treat affected plants. Some years we have even treated plants and vegetables as a preventative measure.

Yu should also make an effort to keep a regular watering schedule and avoid dry outs resulting in plant stress. Good airflow between plants and avoiding to get leaves wet are other measures that will help protect your plants.

You also have the option to choose disease resistant radish varieties. Check with your local garden center but there are varieties that for example are resistant to downy mildew and black rot [4].

5. Harvesting radishes

Most varieties of radishes are ready to be harvested when the base of the root is approximately 2-3 centimetres (about 1 inch) wide.

You will at this stage be able to see the base of the radish root above the surface of the soil.

Always harvest one or two radishes first and taste. The taste will be fresh with a hint of pepper and the texture crisp when your radishes are ready for harvest.

Do not leave your radishes in the ground for two long. The texture will turn wooden and much of the flavor will be lost.

I personally prefer harvesting radishes a bit early to ensure that crisp taste and texture (and to avoid having to wait for too long). 

How to use radishes 

Radishes can of course be used any way you choose. Personally, I have 3 favourite ways to use radishes.

1. Eaten fresh just as they are

Harvest your radishes and put them in ice cold water for a couple of hours. 

Next, wash them and cut off the green leaves.

Now mix up a fresh dip using Sour Cream/Creme Fraiche, salt and pepper.

Add lemon juice or another citrus fruit to add a tangy freshness to taste. 

And there you have it. A perfect way to enjoy your fresh, crisp radishes.

I find that spring varieties are best to eat fresh whereas winter radishes sometimes need a bit of help.

2. Use radishes in salads

Slice radishes and add them to your salads for an instant flavour kick. And why not mix red, yellow and white radishes for beautiful colour contrasts.

Or why not create a creamy salad using Sour Cream/Creme Fraiche, salt and pepper, mayonnaise and thinly sliced och cubed radishes. 

Wonderful to smear on fresh or lightly toasted bread.

3. Add radishes to your raw vegetable salads

Use a mandolin slicer (carefully) to add thinly cut radish slices to your raw vegetable salad. Use tall, slim, oval as well as round radishes if possible.

Add carrots, zucchini, corn, cabbage, celery and broccoli. Now add pepper, salt, oregano and cumin to taste.

Finally add coriander for that fresh zing.

An instant favorite to enjoy with fresh bread or as a wrap.

Helpful resources:

[1] https://www.webmd.com/diet/features/7-healthy-facts-about-radishes

[2] https://extension.umn.edu/yard-and-garden-insects/flea-beetles

[3] https://www.ufseeds.com/on/demandware.static/-/Sites-UrbanFarmer-Library/default/dw0ccd4615/images/content/Radishes-common-pests-and-diseases.pdf

[4] https://plantvillage.psu.edu/topics/radish/infos

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants, and garden vegetables. For the past two years, he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.