Soak Garlic Before Planting – Good Idea?

I have never soaked garlic before planting but it might be a good idea. There is certainly a trend towards soaking with water, fertilizer, fish emulsion or disinfectants. This post will examine these techniques to see if they affect plant growth and the size of harvested garlic.

Claims for Soaking Garlic

Here are some of the claims for soaking garlic. Soaking in fertilizer allows the bulb to pick up moisture more quickly which results in a larger root system before winter. The fertilizer in the water also helps root growth resulting in larger bulbs at harvest time.

Garlic has three major pest problems: fungus, mites and nematodes. It is claimed that a soak in a disinfectant cures these problems.

A variety of soaking solutions are suggested including, hydrogen peroxide, rubbing alcohol, vodka, soap, baking soda, seaweed extract and of course Epsom salt. Some claim that a soak in a warm solution is more effective than a cold one and that repeated soaks are also more effective. Is there a difference between repeated soaks and a longer soak?. The problem is that none of these claims come with evidence to support them – at least not from gardening sources.

Some other claims that are clearly wrong include:

• Soaking will “protect them from diseases”. The DIY solutions might kill a pathogen that is on the clove at planting time, but it won’t protect the clove from infection after planting. Use of a systemic pesticide might, if it is absorbed into the clove.
• Rubbing alcohol kills various types of nematodes. It will probably kill nematodes that are on the surface, but it does not eliminate the bloat nematode, which is the problem pest. Most nematodes are not pests and in fact they eat pathogenic bacteria and fungus that might attack your garlic.
• Soaking improved the flavor – not very likely unless you soak in rum and eat it right away.

I found no evidence that commercial garlic growers, in North America, soak their garlic. Let’s have a look at some of the other claims.

Roots Grow Faster

Some claim that roots develop much faster after a soak, allowing the plant to root down and start on its growth cycle before winter sets in. I have not found evidence that this is true, but it could be. It is true that garlic grows better and larger if it develops a good set of roots before winter. A simple way to accomplish this is to plant earlier than recommended. That gives the bulb time to develop a better root system.

You can see the difference early planting makes in Planting Garlic – When Is The Right Time?

Soaking Garlic in Water

I only found one study, done in Egypt, that compared dry planting to a 12 hour water soak. Soaking resulted in a small increase in plant growth and bulb size, however in this study the germination rate for the cloves was very low – only 60%. Mine is always near 100%.

Soaking Garlic in Fertilizer

The above mentioned study also compared a water soak to a soak in humic acid, both 12 hours duration and found a very slight increase in plant growth and slightly better production of bulbs.

A different study compared soaking in water with soaking in compost tea for either 12 or 24 hours. They found a slight increase in plant size and clove size for compost tea, and a longer soak was better than a shorter soak. The extra growth would be a result of the nutrients in the compost tea and since a longer soak worked better, it does indicate that cloves slowly absorb the nutrients in the soak.

Another test, also done in Egypt, compared no soak with soak in seaweed extract. The extract produced larger plants and bulbs. The soak time was 12 hours.

A fourth Egyptian study tested a soak in mineral nutrients (synthetic fertilizer) and found they increased growth.

I find it a bit odd that all of the studies I found for soaking garlic were done in Egypt and that in at least one study germination was poor. Perhaps the growing conditions in Egypt are such that extreme measures are needed to get a good crop?

Based on the study results it seems as if the cloves do absorb some of the water and probably nutrients in the water. In that case, a soak in any mixture that provides such nutrients should help the plant grow. However, there is no evidence that it provides a big advantage compared to dry planting.

Soaking Garlic to Reduce Fungus

White rot is a fungus (Stromatina cepivorum) that attacks garlic and onion and it is the most important and destructive of the garlic fungal diseases. Studies have shown that soaking the cloves in tebuconazole reduced the disease, although solarizing the soil proved to be just as effective.

Treating cloves with a 10% commercial bleach solution (1 part bleach and 9 parts water) or an OxiDate dip (32 oz per 25 gallons water), a broad spectrum bactericide/fungicide, also reduced issues with surface molds such as aspergillus and penicillium.

A soak in a solution with fungicidal properties can be expected to kill fungus on the outside of the cloves. Things like hydrogen peroxide, rubbing alcohol, vodka should be effective. Soap might dislodge fungal particles, but it is not a fungicide. Baking soda prevents germination of fungal spores on plant leaves, but it does not kill the fungus.

Soaking Garlic to get Rid of Mites

There are two groups of mites that can infest onion and garlic; the family Acaridae and the family Eriophyidae, the dry bulb mite. Treating seed garlic with hot water (130°F [55°C] for 10–20 minutes) before planting will reduce the mite population on the cloves but it might also reduce germination. If you use this technique, make sure you get the water hot enough. Warm water is not much more effective than cold – it needs to reach the higher temperature.

A soak in 2% soap (not detergent), plus 2% mineral oil, for 24 hours will reduce mites. A dusting with sulfur also works. Proper drying before storage helps prevent a mite problem in the first place.

Both the hot water treatment and the soap/oil soak are part of the IPM procedure, so we can expect them to work.

Soaking Garlic to Kill Nematodes

The garlic bloat nematode (Ditylenchus dipsaci) is a very serious garlic pest. Once it is in the soil it takes years to get rid of it. To understand this pest, have a look at the video below.

Sterilizing the surface of cloves will NOT control the garlic bloat nematode.

Treatment with ethoprop resulted in good control early in the season; oxamyl provided good control; methomyl was ineffective. Treating the soil with aldicarb or phenamiphos was also effective.

It’s important to use something that provides systemic control for a nematode soak. None of the DIY products listed above will work.

Is it a Good Idea to Soak Garlic Before Planting?

I think this one is not a complete myth. Soaking in water with or without nutrients may result in better growth, but you should not expect major improvements. For a home gardener it is probably easier to just plant a few extra cloves to get a higher yield.

As for pest management, the above mentioned pests can be significant problems and the above mentioned solutions should provide some relief. The best approach is to start with clean, nematode-free certified cloves and then to follow proper drying and storage recommendations. That goes a long way to reduce a potential problem.

If you do decide to soak for pest control, follow instruction correctly. A lot of online advice suggests a short 10 minute soak – that may not be enough.

More Information On Growing Garlic

Does Real Garlic Seed Exist?

Garlic – the King of Companion Planting

Chives, Garlic Chives, Onion Chives, Garlic Scapes – Which One Do You have?

Leek Moth on Garlic: Identification, Prevention, and Control

Video on Planting Garlic

Video on Harvesting Garlic

Video on Garlic Nematode