How to Grow Garlic in the Tropics

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It’s important to choose the right variety of garlic if you want to grow them in the tropics. Image: © Marian Weyo
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Most of us love to use garlic in our cooking, and many of us like to grow it in our own gardens so we know it’s been grown without lots of nasty chemicals, but in the tropics, garlic is not so easy to grow as in colder climates. Garlic is essentially a cold climate crop, but it is possible to grow garlic in the tropics if you know how.

The most important points are selecting the right variety, knowing how to prepare the bulb for planting, and keeping the plants well mulched. If you don’t get those three things right, then you may get healthy garlic plants, but the bulb won’t form properly. In this article I’m going to explain those points and then show you how to look after your garlic plants. The bulbs that are produced will be smaller than those from cooler climates, but they will still be healthy garlic bulbs.

Choosing the Right Variety for the Tropics

There are two types of garlic. They are called ‘hardneck’ or ‘softneck’ depending on the development tendency of stalks, hardiness, and the pattern of clove formation. It’s the softneck type that we need to grow in the tropics because that type does better in warmer weather.

The softneck varieties produce up to 18 cloves in a bulb (compared to the hardneck varieties which produce up to 10 larger cloves). Although smaller in size, the softneck varieties have the added advantage of being able to be stored longer.

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There are many different sizes and varieties of garlic. Only the smaller softneck types are suitable for growing in the tropics. Image: Maison Boutarin

Some popular softneck varieties are Lorz Italian, Inchelium Red, California Softneck, California Early, Italian Loiacono, Silver Rose, and Silver White. If you can’t find these locally, seek advice from a local nurseryman or horticulturalist as to what warm weather varieties may be available in your region.

Do NOT use the following varieties which are commonly available because they are not suitable for growing in hot weather: Carpathian, Spanish Roja, Chesnok Red, Italian Purple, Persian, and Russian Red. These are all hardneck varieties that are only suitable for growing in cold climates.

Preparing the Bulb for Planting

Garlic needs a period of exposure to colder temperatures for the transition from vegetative to a reproductive state. This is a process called vernalization. Unless you are living in a tropical highland region, it’s not possible to achieve temperatures low enough naturally to do that.

Therefore, we have to undertake the process of vernalization artificially. To do that follow the three steps below:

  • Put the selected garlic bulb in a ventilated bag or a pot.
  • Place the bag/pot in the refrigerator. Don’t freeze It. The temperature should be lower than 10 degrees Celsius, ideally around 4-7 degrees.
  • Let the garlic chill in the fridge for 1-2 months.
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In cool climates garlic will sprout naturally, but in the tropics it need to be forced through refrigeration. Image: © Adrian_am13

Take out the garlic from the refrigerator and separate the cloves from the bulb. By this stage the cloves may have sprouted a green shoot, but don’t be concerned if they haven’t. They will still sprout after planting if the vernalization is done properly.

Site Selection

Garlic grows and thrives well in full sun. The plants need 6-8 hours of sunlight per day to produce healthy plants and bulbs.

Also, there shouldn’t be other root crops in the same growing bed and the growing bed should be free from weeds.

Soil Preparation

The soil for garlic should be nutrient-enriched, well-aerated and loose. Root crops like garlic grow best in sandy loam soil. They hate clay soil. So, if you don’t have suitable soil already in your vegetable garden, you will need to improve it by mixing in manure or compost. You can also do it by adding organic potting mix to your existing garden soil until it is friable and loose.

It’s a good idea at this stage to incorporate an organic fertilizer with a reasonable content of nitrogen into the soil. Well-rotted chicken manure is ideal.

If you don’t have suitable garden soil. You might want to consider cultivating garlic in a container, planter box, grow bag or raised bed. But the depth of the planter should be at least 10-12 inches. If growing in the garden, the tilling depth should be 5-7 inches.

Planting the Garlic

Maintaining proper spacing and plant density are key to good production. The optimum spacing between cloves is 2-6 inches and the rows should be planted 10-15 inches apart. The planting depth should be about two inches.

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Ensure the soil is loose and friable, and plant the bulbs about two inches deep. Image: © ualinochka

You can make a planting hole or line before placing the cloves in the ground or just push the cloves two inches down into the soil if it is loose enough. If the garlic clove has already sprouted, it’s best to place it in a planting hole and cover it with soil. If the sprout is already more than an inch long, then there’s no problem if it’s poking out of the ground.

Mulching

In the tropics it’s important to mulch your garlic plants. If you don’t, production will be minimal. That’s because garlic roots stop growing if the ground temperature is too hot, so the mulching will act as an insulator as well as conserving moisture. Also, mulching helps prevent weed growth.

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The young leaves of new garlic plants emerge through an organic straw mulch. Image: © geoBee

You can use any kind of mulching material, but the best mulch for garlic is straw, well-rotted grass clippings or leaves. Don’t use a mulching material like large pine bark chips which will be difficult for the young shoots to break through.

Irrigation and Fertilization

Provide the plants with a good soak after planting the garlic. It will accelerate the germination process if they’ve not already sprouted. If you provide a good layer (at least 1-2 inches) of mulch, less watering is required.

You may need to water every day during the growing season if it’s hot and not raining, but best practice is to check the soil under the mulch before watering. If the soil is dry, water immediately. The simplest rule for watering is to provide moisture when it is required, but as is the case with all root crops, you should ensure the soil doesn’t become waterlogged otherwise the garlic bulbs may rot.

Garlic needs a heavy amount of phosphorus for optimum bulb formation. You should start fertilizing after the emergence of the true leaves (about six weeks after planting). Bone meal fertilizer is ideal and should be applied every 3-4 weeks.

Alternatively, you can apply an all-purpose NPK fertilizer. But try to use one with a lower amount of nitrogen. It’s better to have applied nitrogen in the soil before planting the garlic.

Weed Management

Your mulching will help prevent the growth of weeds. Thereafter, if you notice any weeds, they should be easy to pull out by hand. If they are not, use a small hoe. Weeds act as a competitor in terms of water and nutrient uptake. So, regular weeding is very necessary.

Pests and Diseases Management

Cutworms, pink stalk borer, bulb mites, leaf miners, onion maggots and thrips are all common garlic pests.

You should check your garlic plants regularly. If you notice any sign of pest damage, spray with an organic pesticide as soon as possible. Neem oil, spinasod or pyrethrin containing pesticides are suitable for controlling garlic pests without resorting to toxic chemicals.

Brown rust, white bulb rot, pink root, leaf blight, neck rot and downy mildew are the major plant diseases that can affect garlic. Fungi are the causal organism of most of these diseases. If you notice green leaves are turning yellow, any spots on the leaves, collapsing tips or softened and necrotic necks, remove the affected plants gently and spray fungicide thoroughly onto the other plants around the affected ones.

Fungicides containing copper, sulfur, mancozeb and neem oil are recommended for garlic. It’s a good idea to apply fungicide as a preventive measure. That way you can keep your plants healthy before they get affected by fungi.

Alternatively, here are two homemade solutions that are useful for keeping garlic pests and diseases at bay:

1. Neem Oil Spray

This plant oil acts both as an insecticide and fungicide. To prepare neem oil spray, mix one tablespoon of neem oil, and ⅓ tablespoon (a few drops) of mild liquid soap into a liter of water and agitate well.

2. Sodium Bicarbonate Spray

This acts as a fungal spray. Mix in a tablespoonful of sodium bicarbonate (baking soda) into a liter of water and add a few drops of mild soap.

Caution: Always spray water onto the plants before applying any homemade or commercial insecticide or fungicide. And always spray in the early morning.

Topping

Some varieties of garlic may produce flower stalks. It’s best to remove these stalks (a process called ‘topping’) as that will improve the yield of the plants. Average bulb weights can be increased by up to 70 percent by removing any flower stalks soon after their development.

Harvesting the Garlic

Withered and yellowed leaves are the signs that the garlic is mature. Start harvesting when the leaf tops begin to dry, discolor and bend towards the ground. There is no harm done if you are late in harvesting, but early harvesting results in immature bulbs which tend to shrivel when cured.

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After harvesting, the soil around the garlic bulb should be gently removed by hand or with a brush. Image: © Andrew Pustiakin

Hand pulling is the best harvesting method of garlic. Use a fork or digger to loosen the soil and pull out the garlic by holding the neck.

Curing the Garlic

Curing or drying should be done before storing. Shake the garlic or brush the bulbs gently to remove any soil on them. Never wash the bulb with water. It can rot the garlic.

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Without proper curing the garlic wont’ store for long. This process can take up to a month. Image: © Leonid Ikan

Tie 10 to 12 garlic stems together with twine and hang them in the coolest place you can find that is dark and well-ventilated area for 20-30 days. Once the roots, leaves and stems are dry, then the process is done. Try pressing the cloves – if they feel hard and firm, then they are cured well.

Storing the Garlic

After curing, take them down, and use a clean cloth or soft brush to clean the bulb of any remnants of dry soil. Don’t use a wet cloth. Then with sharp garden scissors cut the roots off, and also the stalk about an inch above the bulb.

Now put the garlic in a basket or bag that has good air circulation like a woven basket, wire mesh basket, or a reusable mesh bag.

Place the basket or hang the bag in a dark and ventilated space. Don’t store the garlic in wet or damp areas. Many people store the garlic in the refrigerator, but this is not the right way for long-term storage.

Store separately the biggest and healthiest bulbs for your next planting. That will help you to achieve healthy plants in the next growing season.

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