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Greenhouse Gardening – How to Grow Radish?

How to Grow Radish in a Greenhouse

Table of Contents

Radishes grow at lightning speed, sometimes merely within a few days. They are ideal for fresh and particularly inexperienced gardeners. You can easily grow radishes in your own greenhouse even during wintertime without much struggle.

Radish is a root vegetable belonging to the Brassicaceae family. This crunchy veggie is a component of many salads that is native to Europe. Although it now is grown in all parts of the world. Radish is pungent, juicy and sweet and is a great source of folate, fiber, potassium, manganese, magnesium, and calcium.

These guidelines below will show you ways on how to easily grow delicious radishes.

Quick overview of growing radishes in a greenhouse

  • Type: Cool-season crop
  • Time from seed to harvest: 22-70 days
  • Germination temp: 40°F
  • Time until first emergence: 7-10 days
  • Best temp to grow: 50-70°F
  • Height: 6-8 in
  • Spread: 4-8 in
  • Grow from seed: 1/4-1/2 in deep, 1-2 in apart in rows
  • Companions: Chervil, marigold, brassicas, dill, parsnip, pole beans, mint, peas, oregano, borage, nasturtiums, rosemary, eggplant
  • Keep away from: Corn, kohlrabi, sunflower, hyssop, turnips, melons, pumpkin and potatoes

Planting radishes

  • Be sure you supplement it with organic compost or aged manure into the soil, to start with
  • Sow the seeds about an inch into the soil spacing them an inch apart from each other in rows that are one foot apart
  • After the plants germinate, thin them so the plants are spaced two inches apart
Radish sprouts planted two inches apart

A bit of advice for growing radish

  • Ensure the greenhouse kits you have provides your radishes adequate sunlight since shade conditions will encourage the plants to produce more leaves and little of the sweet edible roots.
  • Thinning the plants when they are a week old gives rise to the best roots. If not thinned, you are expected to end up with shriveled, inedible, bad roots.

General challenges when growing radish in a greenhouse

Flea beetles are the common problems with radish since it flies and bounces around. Sprinkling insect repellents such as neem will not be a good help. What you can do is cover them with a mosquito net or insect-proof screen.

Mulch your radishes with fertilizer enriched with wood ashes. It keeps those annoying root maggots at bay and at the same time helps your soil hold moisture that could indicate the distinction between perfect and poor radishes. Do not plant radishes in an area that contained cole veggies in the last three years.

Radishes are virtually disease-free. Long radishes, however, produce black roots that create dark spots at the base of the roots. If this becomes a determined problem, try to grow simply the round radish species.

Radish sprouts and freshly picked radish with the text: How to grow radish in a greenhouse

Watering needs

Radishes require adequate watering meaning the soils need to be wet but not waterlogged. Optimally, provide one inch of water every week. Watering in moderation is the key. If your soil is extremely dry, radishes will bolt and may become short and too sour to taste. If excessively saturated, its roots will break and decay. Do not allow the soil to dry out, and do not keep it dirty, either.

Excellent soil conditions for radishes

Radishes thrive in loose, well-drained soil that is rich in organic matter. It is helpful if the soil has less or no stones at all. The optimal pH for radish-growing soil should be 6.5 but the plant can stand soils with pH ranging from 6.0 to 7.0.

Keep the soil moistened. Avoid fresh compost and organic substances or fertilizers that are high in nitrogen because extremely rich soil will promote lush foliage which will lose crisp, appetizing roots.

Lighting and temperature

The secret is simply obtaining adequate sunshine. Radishes do well if they get at least six hours of full sun every day. They, however, are a cool weather plant and can tolerate some level of shade.

Keep the temperature between 50°F to 70°F most of the time. Don’t pout if you want to grow radish in the heat of summer. Check out our Cooling and Ventilation Collection to keep your greenhouse cool in summer!

Time to reap your radish!

Some varieties of radishes mature as early as three weeks after planting. You will see a big sized head poking out of the ground. To harvest, lift the root off the ground using a fork and cut off the leafy head.

Ready to harvest radish

If you need larger ones, simply leave them for an extra ten days. However, don’t leave them longer than that. If you hesitate to gather them for too long, they will get starchy with a hollow center and it won’t taste good. The leaves are also good so you can also pick a few to eat as they arise, but leave some for the crop. Be cautious as the leaves of the red and roundish radishes will normally have tiny spikes.

When they are left to mature more, they will develop a flower stalk and begin flowering to create seeds. These seedpods are also yummy too! Leave the pods to dry and there you can have seeds for the following season.

Have you ever planted radish before? Leave a comment to share your experience or to ask further questions!
Picture of Jesse James
Jesse James

Jesse James, an Army Veteran, now shares his passion for gardening through engaging articles on Greenhouse Emporium. Leveraging his experience and love for nature, Jesse provides practical advice and inspires others on their gardening journey.

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