How To Grow Big Garlic Bulbs: 5 Easy Steps 9 Comments

Garlic is a wonderful vegetable that many growers enjoy planting every season. It's a fairly easy crop to grow and tends to take care of itself without much effort. The cloves send up strong shoots in early spring and are one of the first vegetables to have large plants once the temperatures warm. It has very few pests or diseases and often grows even when given little care.

These positive characteristics, however, don't always guarantee that your garlic will produce large bulbs. In fact, many growers are very disappointed with their garlic harvest because the bulbs are so small. They often have beautiful healthy plants during the growing season, only to find that they have tiny bulbs when they dig them up.

Obviously this can be extremely disappointing and frustrating for even the most patient gardener or small farmer. The good news is that growing large bulbs isn't that difficult and can be achieved by following these easy steps.
 

(1) Plant Big High Quality Cloves

When planting garlic, it is very important to start with healthy seed stock. This means using quality cloves that are firm, disease free and have not started to sprout. Any planting material that looks questionable should be discarded or used for other purposes like cooking. 

Also, it is best to use large cloves as these tend to produce the biggest bulbs when planted. This means that when you crack (break up) a bulb, the largest cloves are the best ones for seed stock. Some growers will still plant the smaller ones and harvest them as spring garlic (similar to green onions) or allow them to mature knowing that the bulbs will likely be somewhat smaller at harvest.   

Bulbs and cloves come in a wide range of sizes depending on the variety. Some varieties like those in the Porcelain family have very big cloves no matter the size of the bulb. Other varieties like Silverskin tend to have bulbs with a large number of small cloves. When growing large cloved varieties most of the cloves can be planted with great success. When growing small cloved varieties, it is best to use the largest cloves for maximum bulb growth.

(2) Use Good Soil With High Fertility

Garlic is a heavy feeder and requires good soil with high fertility to grow healthy plants and large bulbs. Many growers do not realize how important fertility is when growing garlic and they overestimate the capability of their soil to produce a good harvest. 

Most soils are naturally low in Nitrogen and depending on the location, other nutrients as well. They also have often been depleted from years of farming. Even the majority of soils in most urban yards were once heavily farmed until ultimately finding their way to someone’s garden, meaning they will need some additional care to improve their fertility.

Some growers believe that adding a few inches of compost or manure is enough to meet the fertility needs of their garlic. Although it is true that all soils benefit greatly from adding large amounts of organic matter, it does not necessarily mean that nutrient levels will be high enough for the garlic to reach its full potential after it has been applied. 

Organic amendments like garden compost or manure definitely improve soil tilth (physical condition), moderate moisture conditions and add some nutrients, especially phosphorus, potash and micronutrients. This means they can improve overall growing conditions tremendously, however, they tend to be low in Nitrogen which is very important to growing large bulbs.

By applying a well balanced all purpose organic fertilizer in combination with regular amendments like compost, you can ensure your garlic is receiving all the fertility requirements it needs to maximize growth.

See How To Fertilize Your Garlic for more information.
 

(3) Make Sure To Water Enough

Considering how few leaves they have, garlic plants require a surprisingly large amount of water throughout the growing season to develop and ultimately form large bulbs. Making sure they receive enough water and keeping a proper soil moisture balance is another very important step to growing large bulbs.  

Garlic can survive fairly successfully under drought conditions, however, the bulbs will not fill properly and you will end up with an extremely poor harvest. This is often a major cause of disappointment for new growers who don’t pay as much attention to the moisture needs of their plants through the growing season. One or two weeks of dry weather conditions when the plants are still growing is all it takes for the developing bulbs to lose up to half of their potential size at harvest.

Garlic plants should receive at least 1 inch of water per week on clay or loam soils and up to 2 inches on sandy soils during the growing season. On clay soils, heavy watering spaced out over longer periods is best, while shorter, more frequent watering on sandy soils is ideal. 

Watering should stop about 2 weeks before the garlic will be harvested as it helps promote drying of the plants and curing of the bulbs. This is a natural process where the dry conditions help send a signal to the garlic plants for them to start the final stages of growth and begin to move towards dormancy.

(4) Weed Early, Often & Shallow

Garlic is an extremely poor competitor and needs to be kept weed free throughout the entire season. Any weed pressure will steal sunlight, moisture and nutrients from your plants and ultimately result in smaller bulbs.

It is best to start weeding as soon as the garlic emerges in spring and you can see where the rows are. Ideally it should be done when the weeds are still very small and carried out consistently as the season progresses.

It is very common for growers to start weeding too late, once the weeds are already well established. This makes the process much more difficult than needed and often leads to poor growing conditions for the garlic plants. 

For growers who use mulch for the entire season, any weeds that emerge should be eliminated as soon as they are seen coming through the material. Any weeds not removed will grow into large plants and compete with the garlic. 

One note of caution when weeding garlic is to be careful not to damage the plant leaves. This is especially important once the plants are larger and bulb formation starts, as every garlic leaf that becomes damaged can reduce bulb size by up to 20%.

Also, garlic roots are very shallow and can be damaged quite easily with careless cultivation or when pulling large weeds. When cut or damaged, the roots do not regenerate like some other plants meaning that the garlic can become stunted and will have a harder time forming large bulbs.

(5) Scape Removal

When growing hardneck varieties, scape removal encourages larger bulbs. This is because energy is conserved and diverted to the bulb rather than the flowering structure. Research shows that bulb size can be reduced by as much as 30% when scapes are not removed.

Scapes are usually snapped off by hand or cut with shears just above the last leaves once they begin to curl. You want the cut to dry as quickly as possible in order to prevent a route for infection or diseases.

This means it is best to do the removal during dry weather whenever possible. Scapes are wonderful to eat and can be used in cooking like scallions or green onions. Once harvested they can be stored for up to 3 or 4 weeks.

For more information on growing garlic, see our other blog articles or growing garlic pages. 

About the Author: John Côté owns and operates John Boy Farms with his family who have been farming the same land for over 140 years. As an agronomist and experienced farmer, he helps others learn how to grow garlic successfully. He has written many articles and is the author of The Master Guide to Growing Big Garlic.