Horticulture Magazine

How To Grow Crisp Radish Plants

deep red radish plants in garden soil

Radishes Overview

Official Plant NameRaphanus raphanistrum var. sativus
Common Name(s)Radish
Plant TypeAnnual Vegetable
Native AreaCultivated
Hardiness RatingH4
ToxicityAll parts edible
FoliageLobed leaves with basal rosette
FlowersSmall four-petalled white flowers
When To Sow / Plant OutFebruary, March, April, May, June, July, August
Harvesting MonthsJanuary, February, June, July, August, September, October, November, December
Sunlight

Preferred
Full Sun

Exposure
Sheltered

Size

Height
0.1 – 1M

Spread
0.05 – 0.1M

Bloom Time
Varies

Soil

Preferred
Most fertile soils

Moisture
Moist but well drained

pH
Any

A crispy, mildly zesty component of summer salads in Europe, and a richly-flavoured culinary ingredient in spicy cooked dishes in East Asia, the Garden Radish is a wonderfully versatile root vegetable, thanks to its very varied cultivars.

Apart from being a popular veggie, the Garden Radish is much appreciated by gardeners of all stripes – growing it is quite literally child’s play!

Introducing the Radish

The radish is one of the few truly global vegetables, for it is consumed the world over.

A root vegetable like the potato, it belongs to the Brassica Family or Mustard Family which accounts for its piquant taste.

This tuber’s amazing variety also adds to its versatility: a few cultivars are mild, even sweetish; at the other extreme, a few are pungent. Many cultivars are flavourful with a pleasingly sharp taste.

These various radish cultivars are all cultivated from what used to be a single sub-species, Raphanus raphanistrum subsp. sativus.

While the commonly-cultivated, edible radish was technically a sub-species of Raphanus raphanistrum, the Wild Radish, it is now usually identified by its synonym Raphanus sativus; this elevates the plant to the level of a species on its own.

It has been so altered by millennia of human cultivation that, disconnected from any confirmed wild ancestor, it is technically a cultigen, defined by the Oxford English Dictionary as “a plant species or variety known only in cultivation, especially one with no known wild ancestor”. 

‘Raphanus’ is naught but Latin for radish while ‘sativus’ means sown, cultured, or cultivated as a plant. Raphanus sativus is also commonly known as ‘Garden Radish.’

This species and its cultivars are not to be confused with horseradish which, though also one of the Brassicae, belongs to the Armoracia genus.

The thick, fleshy taproot of the plant is the vegetable we know and love (or not!) as the radish.

Most frequently light red on the surface and white inside, varieties can be white, orangeish, beige, brown, purple, and even black. However, the flesh is almost always white.

many different types of radish in multiple colours
Many Kinds of Radish; Many Hues and Colours!

Types and Kinds of Radishes

Radishes are broadly divided by season of harvest and by shape and size.

Summer radishes are distinctly smaller than winter radishes and are ready for harvest much sooner. Summer varieties are broadly divided into ‘globe’ which are the familiar round varieties and the ‘icicle’ types with elongated shapes.

Larger winter radishes are usually called ‘daikon’ but it is incorrect to refer to all winter types by this term as there are also ‘Chinese’ winter varieties, and the Black Spanish variety. 

Summer radishes are not only easy to grow, they are especially quick-growing vegetables so that within several weeks the gardener’s efforts yield results that are edible and tasty!

As such, summer radishes are an excellent choice as an ‘entry level’ vegetable for the gardening beginner, or to get kids started on growing veggies.

Because summer radishes are small in size and so quick to crop, they are an ‘in-between’ vegetable in more ways than one.

First, their size allows them to be planted in between rows of other, larger vegetables and in small, unused patches of the vegetable garden to fill in the gaps.

Second, because they can be harvested in about four weeks, they can be sown and enjoyed in between the points in time that an earlier vegetable has been harvested and a later one is yet to be sown and grown.

On the other hand, winter radishes have their own singular strength and standout charm, for how many other flavourful and culinary vegetables will keep growing and be good for harvest through the cold and grey Decembers and Januaries, the dead of winter!

Furthermore, just when you would like a bit of spicy zing to your winter dishes, there’s that flavourful radish you had sown back in October!

scarlet globe summer radishes on a wooden board
The Flagship Summer Radish – ‘Scarlet Globe’

Background and Origins

The origins of the Garden Radish are lost in those proverbial ‘mists of time.’ Quite possibly domestication and cultivation of radishes occurred near simultaneously and independently by the Greek and Italian peoples of the Ancient World and the Chinese and Korean people of the same era.

However, archaeological finds suggest that it is more likely that radishes were originally domesticated in the Mediterranean region in about 2000 B.C. which is also where the Raphanus genus exhibits greatest diversity.

In any event, It is safe to say that radishes began to be cultivated no later than the Third-to-Second Century B.C. 

In the 1300s what we commonly refer to as Summer Radishes, small and fast-growing, were cultivated by Italian horticulturists, and these plants made their way to France and the rest of Europe.

Meanwhile, East Asians were developing larger and slower-growing radishes that are known as Winter Radishes. In various South-East Asian cuisines but particularly those of the Koreas and Japan, these radishes are an essential culinary ingredient, just as carrots and leeks are in British and European cooking.

They are prepared with meats, in stews, in stir-fries, and are pickled, among other methods of cooking. The Vietnamese even enjoy a traditional finger food rather like a sandwich with beef and radish as the main ingredients.

Though there are innumerable summer radish and winter radish cultivars, we present four of each kind below, selected for taste, popularity, and ease of finding seeds in the United Kingdom. All of them are sub-species or cultivars of Raphanus sativus.

lots of cherry radishes
The Teeny-Weeny ‘Cherry Belle’ Radish, Crispy and Appetising

Summer Varieties

All of the following summer radishes are cultivars of R. sativus var. sativus – ‘Small Radish’ or ‘Western Radish.’

Cherry Belle is an heirloom variety and is one of those that defines radish to European eyes, being little, round and red. It is succulent with a relatively mild flavour. Among summer radishes, it is also relatively forgiving if picked a little late. One of the fastest-growing summer radishes, it is ready to be harvested in only three weeks when it is about 2.5 centimetres wide.

Scarlet Globe, aptly described by its name, is not too different from Cherry Belle except for being just a little bigger, and good for harvest in about four weeks at an average size of about 3 centimetres. It too is succulent with a relatively mild flavour. But another difference is that it is not an heirloom variety but is an RHS Award of Garden Merit recipient.

French Breakfast 3 really does originate from France and in some parts of France it is actually enjoyed at breakfast. This heirloom variety has a cylindrical shape, is a bright red above while the lower third or merely the lower tip is white. It is big for a summer radish with a length averaging 6 centimetres. It is a mild but flavourful variety that is ready for harvest in about four weeks.

Sparkler in appearance may be thought of as a mix of Scarlet Globe and French Breakfast – it is about the same shape and size as the former with the colouration of the latter, being a bright red with the lower third or only the tip being white. It is crunchy and mild in taste, and is considered one of the earliest summer radishes that can be sown. Ready in about four weeks. RHS Award of Garden Merit.

sparkler radishes pulled from the ground
Radish ‘Sparkler’ – Round, and Red and White

Winter Varieties

The first, third, and fourth winter radishes are cultivars of R. sativus var. niger – ‘Oriental Radish.’

‘Chinese Radish’, or ‘Longipinnatus’, or ‘Mooli’ is a daikon, perhaps the classic daikon. It is a dirty white and ungracefully cylindrical in shape. Typically about 45 centimetres long, it can attain lengths of 50-plus centimetres when ready for harvesting after 60 to 70 days. As it grows about a third of this radish is above the soil’s surface. It is on the mild side for a winter radish but does not have the light mouth-feel of summer radishes. It is used throughout East Asia and South Asia in a vast variety of savoury dishes, further to which condiments, pickles and such are also made from it.

Black Spanish Round is a radish with a reputation. It has a definite kick, rather like a horseradish – it is spicy, perhaps too spicy for some. Another elongated form is also cultivated; it is not quite as spicy. Both kinds are often as black as coal from the outside and as white as snow inside. The round variety is a proper heirloom plant, going back to the Sixteenth Century. Not properly round, it is lumpily round or pear-shaped. Ready to harvest when it is about 10 centimetres wide in 60 to 70 days, even by winter radish standards this one keeps well. It is best used in savoury, spicy soups and dishes.

China Rose is, well, a variety from China that is rose-red in colour. This daikon is cylindrical, rather tube-like, in shape. It grows to 15 to 20 centimetres in length and 5 centimetres in diameter so it is on the small side for a winter radish. Making up for it, this one is flavourfully spicy rather than overly so. As such, it can be enjoyed raw with Spanish or Tex-Mex foods but this versatile daikon can also be used for making soups, stocks and stews. It is ready for harvest in right around eight weeks.

Miyashige hails from Japan. It is off-white and carrot-shaped, typically growing to 35 to 40 centimetres long and 7 to 7.5 centimetres in diameter. It is ready to be pulled up in 50 to 60 days. Not spicy but quite mild, this radish is succulent and flavourful. A great choice if you want to try Japanese or Korean cuisine at home, this radish is also a versatile one as it can be sliced raw into salads, quickly sauteed, or pickled and stored. 

white Japanese radishes lined up
The ‘Japanese Radish’ – Miyashige

Habitat and Growing Conditions

Raphanus sativus or the Garden Radish has escaped from cultivation in some regions of the United States where it is found, albeit infrequently, in disturbed soils, close to vegetable gardens, near rubbish dumps, and alongside highways. 

It takes root in uncultivated but fertile and moist ground in areas with higher-than-average rainfall and with full sun.

In the wild it puts up four-petalled purplish-white flowers that attract bees and other pollinators. It spreads, though very gradually, by seed.

How to Grow Radishes

The sowing and harvesting season are very long, and sowing and harvesting seasons also overlap; thus, radishes can be sown, grown, and/or harvested literally year-round. 

Sowing season runs from March through September and harvesting season from May through the beginning of January. As such, radishes can be both sown and harvested from May through August.

What’s more, most summer radish varieties are ready for harvest about four weeks from sowing.

Winter radishes take much longer to mature, typically about eight weeks though some winter varieties may take ten to twelve weeks.

As a rough guide, sow summer radishes from March through early August, and winter radishes from mid-July to September. Check the instructions on each seed packet for optimal sowing time.

The trick to enjoying a continuous months-long harvest is to sow seeds in small quantities on a regular schedule during the sowing season. This is known as succession sowing.

Most types of soil will do but a balanced mix of clay, sand, and chalk amended with well-rotted manure or organic compost is a very good type of soil for this root vegetable.

The subsoil and underlying ground must be free of stones and rocks.

It is a good idea to hoe or till the bed to prep and loosen the soil. It must drain very well and not be prone to waterlogging.

Soil pH ideally should be in the Slightly Acidic to Neutral range, that is 6.1 to 7.3, but here too radishes give you a fair amount of leeway.

French Breakfast radishes in red and white
‘French Breakfast’ Radish – Notice the Distinctive Shape and White Tips

Summer radishes should get morning sun and indirect sunlight or shade in the afternoon, especially in the sunnier parts of the country. Winter radishes may be grown in full sun locations.

Besides outdoor beds, summer radishes and the not-so-big winter radishes may even be grown in planters or large containers. Some summer radishes can even be grown in grow-bags.

Sow summer radish seeds in rows with 2 to 3 centimetres between seeds, and with rows spaced about 15 centimetres apart. Seeds should be sown 1 to 2 centimetres deep and just lightly covered with soil. You may sow them on a fortnightly basis from mid-March through early August. 

Winter radishes are significantly larger vegetables so their seeds should be sown (in rows) with 15 to 20 centimetres between the seeds in a row, otherwise sow them about 10 centimetres apart and thin the plants when they are young. However, as radishes are very reliable crops, if your garden is not unduly troubled by pests and diseases and has good soil, you may as well sow the seeds with the aim of reaping a near-full harvest and without the intention of thinning. 

Water well and regularly, say twice or thrice a week, such that the subsoil stays moist. Keeping the soil moist is of special importance when growing summer radishes in full sun. 

Soil moisture is also a factor when growing winter radishes. If the soil dries out and remains dry for some days, the radishes’ growth will be stunted and they may well end up bland and tasteless, lacking their distinctive rich, flavourful appeal.

Chinese radishes poking above the surface of the soil
As it Grows, ‘Chinese Radish’ Stays Partially Above the Soil Surface

Harvesting Radishes 

When harvesting summer radishes, the general guideline is that it is better a little too early than a little too late.

If you harvest summer radishes a little too early you lose nothing except a bit of size. Pick them a little too late, and the vegetable can quickly become stringy or woody, depending on the variety, with the taste becoming flat, bitter, or unpleasantly pungent. 

To use size as a general guideline, it is at about 2 to 3 centimetres in width that summer radishes are young and are best harvested.

While summer radishes must be harvested on time, winter radishes allow more flexibility though do not leave them in the ground too long either.

Pick winter radishes by eyeballing the width – when a given vegetable looks like it is more or less the correct width for that variety, it can be pulled up.

Harvest them early for slicing raw into salads, and late for making pickles, gazpachos, stewing, or for culinary use. Keep in mind that not all types of winter radishes can be enjoyed raw.

If the atmospheric temperature is predicted to stay at -5° centigrade or less, you should pull up any remaining winter radishes otherwise they could sustain frost damage. This should not be a worry virtually anywhere in the United Kingdom except parts of Scotland.

To pick a (small) summer radish, grasp the leaves at the top, wiggle the radish loose, and gently pull it up. It may not work out quite that way with (larger) winter radishes – the elongated or cylindrical types are much longer and much heavier.

You can end up with only foliage or a split or broken radish in your hand! If you do not feel the radish getting loose and coming up through the soil, lightly dig around it and remove and loosen the soil until the radish is ‘unstuck’ enough to pull up.

Summer radishes should be enjoyed soon after they are harvested, when they are fresh and succulent. Winter radishes may be stored as they will keep well in the fridge’s crisper or even in a bin in a cool basement.

The leaves of winter radishes are not only edible, they have their own taste merits. They do not keep well and should be consumed fresh, within 24 hours of picking.

They are wonderful additions to any salad, are first-rate ingredients for pestos, add flavour to soup bases, and can be added to spinach and kale dishes. 

Korean radish kimchi in a white bowl
Korean Radish Kimchi, Anyone?

Common Diseases and Problems

The flea beetle is perhaps the most common pest to attack radishes. Flea beetles chew up the leaves, especially of young plants, weakening and stunting the growing root vegetable.

Organic solutions may be used to kill these pests and the plants can be protected with narrow-gauge wire netting.

Brassica downy mildew is a disease that radishes are prone to. It is a serious disease that destroys the root vegetable.

It is identified by an ‘icky’ white growth covering the foliage, and yellowing of the foliage. Promptly remove and destroy all affected plants. Retail controls to treat downy mildews are not available.

Slugs and snails eat radish seedlings. These common garden nuisances are more easily dealt with.

Where to Get Radishes  

Seeds for summer radishes, as popular as they are, are widely available. You can buy different kinds from your neighbourhood garden centre and through most online merchants. 

Seeds for winter radishes may not be quite as easy to find but this vegetable is catching on fast in the United Kingdom and like as not you’ll find at least two or three varieties at the bigger garden centres and online merchants specialising in vegetables.

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