Growing Garlic is something of an Art-form

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The Secret Art of Growing Garlic

Growing garlic is easy, but the secrets of growing good quality garlic have only recently become more widely available.

Three development stages of Garlic.

In the past I have seen people grow garlic and talked to them about it, but this year was my first effort at actually grown it myself. I would have to say, I got a reasonably good crop, but the plants were small and most had only one large, round clove (like the one in at the right of the photo).

I think the big mistake I made was assuming that growing garlic would be much the same as growing onions. Once bulb formation begins, this would be true, but growing garlic in the early leaf-froming stage is really more like potatoes. Still, it was a good learning experience and with a bit of further research, I discovered some secrets that many others seem not to talk about much.

But first, lets go back to the beginning:

History of Growing Garlic

OK, this is just something of an interest for me, but the domestication of Garlic is a bit unusual.

Like many domesticated plants and animals, the origins of garlic in cultivation are not recorded. However, records of garlic indicate it was being widely grown about 3,500 years ago and so estimates put the beginnings of domestication around 5,000 years ago in the region where it evolved (the Caucasus Mountains between the Black Sea and the Caspian Sea). From there, it seems to have spread rapidly throughout Europe, the Mediterranean and Asia, diversifying into many regional-specific strains along the way.

Bulblets forming in the flower-head of garlic.

The really unusual aspect is the sterility of domesticated garlic. Modern varieties either produce small bulblets from the flowering head, or only 'apomictic' seed (ie. without pollination). For many years, it was also believed there was no wild ancestor surviving, but an American expedition to Eastern Europe in the 1980s managed to bring back some wild seed-bearing garlics.

Since the discovery of these wild varieties, some have suggested that true domestication can begin - since they feel domestication involves selection of improved seed-bearing lines and hybrids. However, the reverse is actually true.

Few plants are naturally sterile, but those that are still have some means of dispersal. Not so for Garlic - it is completely dependent on human cultivation for its survival. Plants could persist in one place for a few seasons perhaps. However, they could not spread and, in most regions, would eventually die out as the bulbs also need careful storage to survive between growing seasons.

Actually, if the wild plants had not been found, garlic - like Corn - would have the status of a true 'Cultigen' (literally a plant 'generated in cultivation'). In fact, actually growing garlic reveals there may be even more to selection for sterility than you might expect (see below).

The most likely scenario - given its rapid spread through Europe and Asia during the initial phase of domestication - is that wild seed-bearing plants spread around the World and these were eventually selected in ways that led to one form of sterility or another. This essentially fixed the characteristics of the plant to suit the needs of people in the various areas where they were growing garlic.

Thus, the reintroduction of seed-bearing characteristics actually represents a kind of reversal of the domestication process. However, it has also led to the recent development of onion-garlic hybrids and these have shown improved health benefits due to the combination of functional compounds from each parent. the 'take-home' lesson being that a combination of alliums (garlic, onions, leeks and shallots, etc.) is better for your health than just using garlic alone.

Growing Garlic

Growing garlic is much like growing any bulb-forming plant. One problem often encountered when growing many types of bulbs is that of selecting only the biggest ones and discarding the rest. Have you ever known a gardener who liked Gladioli, but lamented the way they all seemed to turn white after a few seasons. Well, white varieties are stronger and generally produce the biggest corms. By throwing away the 'runts', the gardener was actually discarding all the nice colors and selecting for white!

Something similar happens when growing garlic. We like to eat the biggest and juiciest cloves, but these are also the ones needed for planting, to ensure a good crop. Early garlic growers would have encountered the same problem and could well have preferred sterile forms to use the small bulblets from the flower head as propagation material, rather than risk the next seasons crop by eating the best cloves each year.

These bulblets (and small cloves) will not produce good garlic in a single season from planting, which means you should probably look for ways to grow plants in various stages of development. For instance, you could grow bulblets in a container for one season, to produce single bulb planting stock. Then plant these into a sunny, well-watered garden bed the next to produce planting cloves for the third year's garlic crop. I will be starting a system like this in the coming season, so I'll let you know how it goes.

In general, the most important things to consider in growing garlic are:

Variety,
Planting time,
Soil preparation,
Harvest and storage

However, garlic is a long crop (ie. takes a long time to grow) there is ample time for something to go wrong. One of the main difficulties with growing garlic is that is likes warm, sunny conditions, but also requires continual moisture supply. Together with its soft leaves that look a bit wilted at the best of times, this presents the danger of the crop suffering a check in growth before it shows signs of wilting. One strategy I use is a mulching layer of straw to help conserve soil moisture in warmer months.

Such checks in growth are the main cause of a poor result, so everything else is aimed at preventing them from occurring.

Garlic varieties

Recent genetic analysis has revealed ten groups of garlic:

Five hard-neck groups - Porcelain, Purple Stripe, Marbled Purple Stripe, Glazed Purple Stripe, and Rocambole
Three weakly bolting hard-neck groups - Creole, Asiatic and Turban, plus
Two soft-neck groups - Artichoke and Silverskin

In choosing from this selection it is important to remember that each one is suited to particular climatic conditions ranging from cool temperate to sub-tropical.

In general, Asiatics, Turbans and Creoles prefer warmer climates, while Rocalmbole and Soft-necks prefer cooler conditions. However, all are 'Long-day' plants, requiring day lengths of 14 to 16 hours for bulb formation. This keeps them out of the tropics and also makes planting time and crop establishment very important.

Planting Garlic

When growing garlic, planting begins in Autumn, but not too early. Wait until soil temperatures have fallen below 15°C (taken around 9am). This will keep the bulbs from growing away too quickly.

Make sure they are planted at a depth of only 3cm to 5 cm (depending on the size of the clove), into raised beds to keep them from sitting in wet soil for long periods. In the early stages, the focus is on leaf growth prior to their 'dormant' period during Winter.

This means that while planting should not be too early, neither should it be too late, as there needs to be enough time for leaf growth before conditions become too cold. Temperate growing varieties also need a period of 'vernalisation' before bulb formation begins. This can be as much as 6 weeks (depending on variety) of night temperatures below 5°C (40°F).

Clearly, the balance needed between moist and dry, as well as cool and warm, mean that garlic is often on the brink of being damaged by various soil-borne 'rots'. This proper makes soil preparation for garlic growing vital.

Soil Preparation

Much of the information you need here can be found in our Soil Improvement section, but there are some special considerations when growing garlic. Specifically, you need a very well drained soil that is also good at retaining moisture.

In sandy conditions, it may be worth planting garlic above a layer of well made compost, mainly to improve moisture retention. In heavier soils, don't just rely on cultivation, make sure you do everything you can to maintain strong soil structure.

As mentioned earlier, the requirements for growing garlic are more like those for potatoes than onions. This means garlic will need a fair bit of Nitrogen - but only in the early leaf-growing stage - so don't overdo the fertilizer.

Phosphorus will be essential for good root development and potassium for leaf growth and bulb quality. Also, the compounds that give garlic its health benefits are mostly Sulphur compounds, so this nutrient will also be important. In general, it is best to use an organic fertilizer based on either Poultry or Cow Manure, as these will give the best balance of nutrients.

For Sulphur, sprinkle a little Gypsum over the bed after the plants begin to emerge.

now there is only one more thing to consider:

Harvest and Storage

Just as with planting, harvest of garlic should be not too soon, but not too late. A general rule of thumb is to harvest when about two thirds of the leaf area has died off, but it is often better to try a 'test plant' first. When you think the time is about right, dig one plant to examine the condition of the sheaths covering the bulb and the basal plate. The cloves should be firm, with tight 'skins' and no sign of decay in either the sheaths or the basal plate to which the cloves are attached.

A bulb in this condition and with a covering of two or three dry sheaths will have the best storage characteristics.

The bulbs should be hung (with a few inches of the stem attached) in a cool, dry and well ventilated place. However, the cloves will deteriorate after a while, so for long term storage (once they are properly dry) the bulbs can be kept in a paper bag (not plastic) in the vegetable crisper of the fridge.

Planting bulbs and bulblets should also be stored in a similar way to ensure they are still in good condition for the next season.

All things considered, growing garlic makes a very interesting project and with new varieties coming along, it should be a topic to keep up with. To help, we have added some useful links below and you can also subscribe to our Free email newsletter - The Food Gardener - to make sure you don't miss anything new that comes along.