How To Grow Radishes

Growing radishes is very easy as they are a very quick crop, ideal to get the children involved in growing their own food. The radish is a member of the brassica family which includes plants such as cauliflower, cabbage, kohlrabi, and broccoli the name of a few. This family of plants are generally quite resistant to low temperatures which means that radishes can be grown throughout the year in most climates except ones that are extremely cold in winter or extremely hot in summer.

Grow radishes in the unheated greenhouse from February, and direct outside from April. Radish seeds can be sown again outside in late summer and in the autumn inside the greenhouse. This way you can have a steady supply of radishes for a long period.

Radish Varieties

  • Winter radishes are cold tolerant and can be growing outside in very low temperatures. Winter radish is for example the Black round Spanish radish.
  • Round radishes are the most commonly available variety, commonly found everywhere. These are summer radish type like the variety Cherry belle. This variety is grown widely as the common garden radish.
  • Long radishes are better suited for loose soil as they have a longer cylindrical root. The white root types are winter radishes.
  • Mooli type radishes are one of the longest root vegetables and better suited for a deep container garden.

Growing radishes with other crops

Additionally, they have the added advantage of being extremely rapid growers, so crops can be produced in as little as 4 to 6 weeks depending on the specific temperature at which plants have grown. This allows radish radishes to be used between other crops that take longer to germinate. 

A common example of this, is planting seeds with radish seeds directly into the garden with carrot seeds. This is done to show the positions of the carrots which can sometimes take a long time to come up. This is helpful when trying to keep a weed free garden without accidentally removing your carrot crop.  

However, due to the speed at which radishes grow, they can be harvested and removed from the area before the carrots reach any reasonable size which is an excellent way to maximise the output of your garden. 

Sowing radish seeds

As mentioned above radish seeds can be germinated year round as required, however, the length of time which it takes were radish seeds to germinate does vary substantially depending upon the temperature. Studies have shown that radishes take around 30 days to germinate at 5C but that time reduces down to between 4 and 6 days at temperatures of 15 to 20C. So ideally a minimum temperature you should be sowing seeds is at around 15C.

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Radishes like neutral soil and slightly acidic soil but can thrive in most soil types. Dig in fresh manure the previous year so that radishes have plenty of nutrients to form bulbs quickly. Radishes grown in poor, stoney soils go woody and bitter.

Plant seeds indoors

So if radishes are sown in the early spring it is important to grow them in seed trays to ensure that rapid germination occurs, however, as temperatures improve in late spring direct sow seeds outdoors into the garden.

If you are sowing seeds we recommend using a modular seed tray and filling it with good quality seed raising mix which is designed specifically for this job. This can be done inside as early as March.

When filling the tray it is recommended that the seed raising mix be firmed into the modules to create solid plugs. Water the soil surface gently until the compost is evenly moist to give the radish seeds the best possible start. The advantage of doing this is it makes it easier to transplant seedlings later on.

Multi-sowing

When sowing the radish seeds we recommend planting between 4 to 6 seeds per seed cell with the aim of getting four seedlings per cell. This is a method is called multi sowing and is recommended by well known market gardener Charles Dowding. This method has several advantages over planting single radish plants by themselves.

The first advantage is that you get more seedlings per tray which maximises any heated space that you have for growing seedlings. Secondly, sowing in clumps means that when you transplant the seedlings into the garden it is much faster to do so as you are planting four plants instead of one with each seedling plug that is transplanted.

The third significant benefit is that because the plants are in clumps they can be spaced further apart without reducing the yield from a given space. This also makes maintaining the plants easier because you can run a Dutch hoe between clumps easily rather than hand weeding.

Plant radish seeds outdoors

This is the most common seed sowing method as radishes are so quick to crop. Direct sow the radish seeds in a well raked soil. The ideal planting depth is 1 – 2 inches deep. You can dig in a small amount of organic matter into the soil the previous autumn, but it is not a must.

Plant radish seeds at least 1 inch deep, water seeds well especially in hot weather and the seeds will germinate in 5 – 20 days depending on the temperature. Keep the soil moisture at optimum level by watering the radish seeds every 2 – 3 days.

Planting radish seeds is very easy and can be done almost all year around. Even the children can grow radishes from seeds as it is one of the easiest vegetables to grow.

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Looking after radish seedlings

Radish seedlings will appear relatively quickly in your seed tray, within a week or so. At this point is important to ensure that you keep the plants moist to encourage rapid growth. Typically, radishes will only need to spend 3 weeks or so in a seed tray provided that the conditions are reasonably warm.

If you are growing radishes in clumps it is important to ensure that the number of seedlings per clump is around four plants. If you have more than four in an individual clump it will result in the radishes being significantly smaller, so thin the radish seedlings before transplanting them.

Also when you sow them in the garden thin seedlings regularly so you can have good sized roots.

Planting radishes out into the garden

As mentioned earlier in the article radishes are relatively frost tolerant plants which means that they can be planted out into the garden as soon as the seedlings are ready unless the temperatures are below freezing on consistent basis. Radishes can typically survive in temperatures as low as -3 to 6C. As long as the soil does not freeze radishes will be okay.

However, despite the fact that radishes can tolerate these temperatures we still recommend only planting them out once temperatures are consistently above 10C as this will ensure that the radish plants grow at a reasonable rate.

When planting the radish seedlings out into their garden bed they need to be placed in rich, moist and free draining soil that has plenty of nutrients. If your soil is somewhat impoverished add compost to the soil. 

In terms of light requirements radishes are quite forgiving and can grow in both sunny locations and partially shaded locations which will slow down the growth rate.

If you are planting in spring or autumn select full sun locations where possible. However, if you are attempting to grow radishes in really hot temperatures, you can sow the seeds in early summer in shade, to ensure that they do not bolt to seed too quickly.

Caring for radishes

Once the radishes have been planted it is important to protect them from slug and snail attack as they can be somewhat susceptible. To do this we recommended using snail pallets, which need to be sprinkled all the way around the seedling to ensure no slugs can access the plants without coming into contact with the pellets.

If you want a mild flavour from the roots pick them young. Summer radishes are the best for overall use if you want to plant radishes from spring till late summer. Winter radishes can be sown in late summer and in the autumn in the greenhouse.

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The other key factors to growing successful radishes is to ensure that the beds are kept free and the plants are watered regularly. This is particularly important in cases where there is minimal or sporadic rainfall.

Radish problems

Radish is from the cabbage family therefore the flea beetles can cause problems. They eat the young seedlings, causing tiny holes on the radish leaves. And can even eat the entire plant and cause a total crop failure. Get rid of infected plants and spray the radish plants with a home made garlic spray.

Radishes can not tolerate heat so best to grow radishes in the summer in semi shade, although make sure to avoid too much shade.

Root maggots can also be a problem while growing radishes, if you have a rich soil for your radish bed they should not be a huge problem as the roots will be growing healthy with the proper nutrients in the soil.

Harvesting radishes

Radishes will develop very quickly particularly as the weather warms up in late spring. As result of this you need to monitor the progress of the radishes every few days and harvest radishes as they are ready.

Harvest radishes at any stage once they reach a reasonable size which the most varieties is once it is the size of a marble or a little bit larger.

If you are growing radishes in clumps and you do not want to harvest the entire clump then select the largest ones first. To remove the radishes twist the radishes rather than pull them as that will remove the root without pulling up the entire clump.

Eat the radish thinning

When you thin radishes you can eat the small roots too. Also the young radish greens are excellent in salads and in quick stir fries.

As the growing season progresses you will never inevitably find that there are radishes that have not been harvested before they start the bolt. At this point these plants are not suitable for harvesting plants for the root, however, they still can provide some useful products for the garden and kitchen.

Eat the seed pods

Radish plants can be allowed to form seed pods which can either allowed to fully mature and produce seeds. These can be collected for the following year or alternatively the seed pods themselves can be harvested and used as a snack when they are still green and immature.  

The pods taste relatively spicy and go particularly well as a snack when drinking beer so if you got excess radishes and you haven’t tried this before, give it a go. Growing radishes is just so much fun and you can eat the whole plant even the seed pods, which just shows how brilliant this small root veg is to grow in the garden.

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