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GARLIC GROWING GUIDE
The ten stages of growing garlic
Garlic is a sorely misunderstood plant. It is considered to be a food, a spice and a herb. It is a perennial root species grown as an annual root vegetable. What most of us see as a millimeter-thin root base is actually the stem, the edible cloves are swollen leaves, and the bulbs swell only when the plant is dying.
Garlic has a unique smell and taste and proven antibiotic and anti-inflammatory powers but the jury is still out as to whether or not it wards off demons, werewolves and vampires.
What is Garlic
What is Garlic?
Garlic is one of the 800 Allium (onion, leek and chive) species and one of just seven that are cultivated. It is the slowest vegetable to mature.
Garlic is a single species (Allium sativum), and is divided into two sub-species being sativum (non-bolting types silverskin and artichoke varietal groups) and A. ophioscrorodon (bolting types of turban, creole, asiatic, porcelain, rocambole, standard purple stripe, marbled purple stripe and glazed purple stripe varietal groups). Effectively the two sub-species are distinguished by softneck garlic which that does not send up flower stalks, and the hardnecks that do.
Knowing how to distinguish the parts of the plant and how the plant grows will help you with your own crop. We could say: get to know your garlic before you grow your garlic. Garlic consists of several parts as the diagram below illustrates.
Garlic Plant Diagram
Garlic Bulb Diagram
Roots & Basal Plate
From bottom to top a mature garlic plant consists roots, a flat basal plate which holds the bulb with one or more layers of cloves under its skin (wrapper).
The bulb consists of a cluster of cloves. In a softneck bulb the cloves are arranged normally in three layers (the smallest in the centre) forming an oblong bulb shape. Softneck have two fertile leaves which support the bulb development. In a hardneck bulb the cloves generally have a single radial appearance with one fertile leaf.
Depending on the location in New Zealand and the garlic group (cultivar), garlic clove is planted between March and June and harvested in November to February. Garlic develops its roots first and then produces leaves later - normally 1-2 weeks later for early harvesting garlic, and up to six weeks for late harvesting types. In the germination period in autumn and early winter the plant will produce 3-6 leaves before the cold harshest part of winter begins.
During winter if the temperature is below 12°C (a temperature below which the plant is dormant) the garlic plant will have little to no growth. Once spring appears and temperatures rise above the dormant temperature the garlic rapidly grows and expands.
Bulb formation is dependent on a prolonged cold period, followed by warming spring weather, and increasing daylight length. When the air temperature and soils warm, the plant rapidly grows for 3-4 weeks before forming a bulb.
Some garlic groups need more or less of these factors for bulb swelling. Bulbs and cloves grown in colder climates will generally be bigger (particularly the strongly bolting hardnecks) but with fewer cloves.
The cloves (2-30) cling together and are the part of the plant that most people divide, eat or plant to grow their next garlic crop from the bulb. The shape of the different garlic group cloves vary.
Leaves & Scapes
The bulb supports the tall and narrow pseudostem or false stem (technically they are leaves) plus a cluster of leaves. The pseudostem is supple for A. sativum or softnecks (the ones you can plait) or firm for the A. ophioscrorodon hardnecks. Normally, cutting the bulb off the strong stalk of the hardneck after drying requires secateurs.
The eight hardneck varietal groups generally send up a long, strong stalk late in the season known as a scape.
The eight hardneck varietal groups generally send up a long, strong stalk late in the season known as a scape. The scapes' flower stalk (technically an umbel) produces bulbils - this is a secondary survival mechanism for the plant. Bulbils' size can be rice-sized to pea-sized depending on the varietal group. They are in fact clones of the plant just like the bulb and cloves. While people often call bulbs or cloves seed this is not strictly correct, it's just that until recently that was the only way to garlic could be grown. Around the bulbils of the scapes, flowers can form. For more about bulbils, visit our bulbil planting section.
Very rarely the flowers can produce viable black-sand sized seed known as 'true seed' or TGS. With prolonged cultivation (asexual using cloves) over thousands of years, garlic has almost lost the ability to sexually reproduce.
It's a marvel for anyone to grow and produce garlic seed these days which normally comes from the purple stripe cultivars with strongly bolting and flowering plants. These are the closest relatives of the old wild garlic. True seed generally does not carry over viruses and has increased vigour allowing growers to selectively breed desirable traits.
In NZ it is rare to find someone trying to grow garlic true seed, rarer for the flower to open and seed to form, and nearly impossible for the seed to be fertile and grow into new garlic. We would be keen to learn of any kiwi TGS legends out there. For more about to grow garlic true seed, visit our true seed section.
Being the longest growing annual crop, garlic has several stages that take several months to pass through to reach maturity. A planted clove needs to send down roots first before sprouting before winter. The first signs of any diseased cloves can be found at seedling stage with rogue plants.
Over winter in colder areas the plant does not grow while in warmer areas slow leaf growth continues. It is not advisable to apply any fertiliser during this cold period as there will be little uptake.
In early spring the plant puts alot of its energy into stalk thickening and leaf growth. By late spring and early summer the plant transitions with scapes and some leaves begin browning off as the plant puts its energy into bulb development. The leaves are vulnerable to disease garlic rust at this stage.
The final stage is when when bulbs develop cloves and they begin to swell. By now many leaves are browned off and the bulb and basal plate is most vulnerable to wet weather diseases which might be brought over to when it is harvested and cured.
Wild garlic originates in the cold climate of central Asia, on the north-western side of Tien Shan - the 'mountains of heaven'. This long mountain range borders Uzbekistan in the west and China and Mongolia in the east.
Wild garlic still grows here and its closest relative is the Standard Purple Stripe group. Garlic was traded via the spice and silk roads over millennia. The Mediterranean, Continental and Asiatic cultures have grown the most desirable aspects of the garlic genetics to suit the regions' climate and specific cuisine of those places.
These provincial garlics (of hundreds of cultivars) have shaped the characteristics to help form the ten different global garlic groups we have today.
Garlic has been grown and traded for over 5,000 years, with Egyptian tombs depicting garlic bulbs and scripts describing medicines and forms of cooking with garlic. From there garlic spread throughout the ancient world with varying climatic conditions.
The widespread cultivation around the globe using cloves (clones of the bulb) over the millennia led wild garlic to diversify into different types - it also resulted in a decline in its ability to sexually reproduce. Epigenetic changes in morphology to adapt to climate conditions, softneck garlic types evolved in a warmer climate and were selected for non-bolting characteristics. These will revert to producing scapes in colder climates. Thus today all garlic is one species (allium sativum) with ten main global cultivars also known as 'garlic groups'.
A generation ago there were many large NZ commercial growers of garlic and the sector was in a healthy state like other horticultural and agricultural industries. In the early 1990s the import tariffs were removed from garlic. Our commercial growers could not compete with low-priced Chinese grown single-cultivar imports. Today 3/4 of the world's garlic (about 30 million tonnes) is grown in China, almost all grown in the province of Shangdong. The NZ garlic industry was crushed.
Today the NZ garlic industry consists of only a couple of large-scale growers. They supply the most economicly viable softneck garlic groups which have plentiful clovesthus making it more economic for resowing.
To realise the potential different garlic types to grow and thirive in your area we invite gardeners to explore both the tastes and the variability by offering the widest range of garlic groups available in New Zealand.
Garlic Groups (Varietal Groups)
Garlic is not all the same. There is a range of garlic groups (or varietal groups) which have different optimal times to plant and harvest, their storage length varies as do their flavour attributes. The groups were named by American garlic guru Ron Engeland in 1991, and a decade later his groupings were confirmed by genetic research.
The 10 types of garlic in the group are the two softnecks - silverskin and artichoke, the three semi-bolting hardnecks: creole, turban and asiatic garlic, and the final five strongly-bolting hardneck garlics: porcelain, rocambole, standard purple stripe, marbled purple stripe and glazed purple stripe. Try our garlic group picker to help decide which garlic to grow.
There is alot of confusion over the different names growers put on garlic. Some names like 'Red Russian' is a marbled purple stripe, while 'Russian Red' is a rocambole and is sometimes even an elephant garlic (which is a leek!). It is more useful to identify garlic using the ten global garlic groups because outside the of the groups variability differences are only related to local growing conditions.
Genetic studies by Volt et al in the 2000's identified that garlic is one species with ten main garlic varieties scientifically known as 'garlic horticultural groups' or garlic groups. She found that each group is distinct as related to the bulb arrangement, size, number of cloves, clove colour and tightness of cloves, and number, size and colour of bulbils irrespective of where they are grown. All other variances relate to the variability of local growing conditions and are not reliable.
The diagram below (greatly simplied from the genetic research of Volk et al) shows the genetic diversity between the different groups as a result of genetic sampling. Note the relationships and how the softneck garlics of silverskin and artichoke are not closely related, nor are they closely related to the hardnecks of the purple stripe groups. Also of interest is the close relationship of silverskin and creoles.
Other characteristics such as bulb wrapper colour and size is highly dependent on the location in which they are grown. Nutrients affect bulb size and weight , while scape development is affected by climate, with humidity affecting scape curl. However, growers have noticed that the shape and colour of the scape's umbel base is different within each group. Shape and colour of the spathe varies within each garlic group. The base of a turban and marbled purple stripe have a red blush. Rocamboles and porcelain spathes turn white at maturity and Asiatic scapes have an elongated dimple.
So in summary, outside genetic tests only the leaf and clove appearance, bulbil characteristics and scape shape and colour can be used to identify the ten groups. The chart below shows some of the differences of each garlic varietal group.
Planning Guide Chart
Another factor to consider is that garlic that is moved to a new region will take time to acclimatise to the new location. Some of the traits known for a particular garlic group might take a year or two to occur in a new location and soils.
It is also known that garlic grows better when they are moved from a colder climate zone to one which is warmer. Thus it is best to ensure garlic bulbs/cloves are obtained from a cooler climate rather than a warmer one, otherwise they are likely to miniaturise for the first couple of years until they acclimatise. It's like a Northlander coming down here to the deep south in autumn only wearing a t-shirt and taking time to get used to our colder climate.
Do not attempt to grow garlic which as been imported. This is for three reasons; firstly: they have only been imported for culinary purposes and have NOT been checked for disease - no gardener wants to introduce a new disease to their soils. Secondly, they are likely to have come from the northern hemisphere (most likely China or USA) and will not aclimatise well. Thirdly, they are likely to have been sprayed with a shooting hormone to stop it from shooting during storage - it will not grow properly.
NZ culinary garlic is normally smaller and has been put in a cool store which interferes with its growth often getting secondary shooting if planted. Large NZ commercial growers who grow for culinary use often use the chemical maleic hydrazide which is a sprouting inhibitor as it is not intended for planting. As a result we recommend planting cloves from bulbs which are recommended for gardeners than the plate.
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