How Seed Soaking Affects Seed Germination

When seed starting time comes around, we all have one thing in common: we want to see the best germination rate possible. Part of this is purchasing from a reputable source, but there are other factors that can help the process be most successful. Seed soaking is one of those factors. 

Nature has a funny way of giving plants the right treatment to help them germinate. In the environment where they are native, the weather between fall and spring is what determines the success of that plant in the following year. For fruit trees, this means getting a certain number of chill hours, for example. 

For many herbaceous annuals, perennials, and biennials, the weather performs a different role. Temperature, moisture, and the shifts in weather in general all play a part in ensuring the survival of that species. That means when we are doing the planting, there are things we can do to help bolster the germination rate. One of those things is soaking. Let’s discuss how this works and how to do it. 

Germination Factors

You may have noticed in the past that some seeds germinate well while others can be spotty at best. If you’re giving all of them the same treatment, there is a good reason for this. All of them need a certain combination of circumstances for optimal performance. There are other factors that can come into play, like nutrient availability and cold stratification, but these are the main drivers. 

Moisture

Water is one of the more significant factors in germination, and without it, you’re unlikely to see any action in those beds. It is responsible for jumpstarting the metabolic process. 

Moisture causes the seed to swell and, ultimately, activates enzymes in the embryo. The nutrients stored inside are then utilized to feed the embryo. As the embryo swells, the hard shell splits, and the seed sprouts. 

Light

Some species need light to germinate. These are the ones that tell you to surface sow. Surface sowing is placing them on the top of the soil and pressing gently. This way, they have moisture from the soil and the light they need to produce hormonal changes, which trigger germination. This usually applies to those that are small and don’t store as much energy.

Temperature

Every plant has an optimal germination temperature.  This regulates hormone production, enzyme activity, and moisture absorption. Until the soil reaches the right temperature, moisture absorption won’t occur. So, this is an important factor in getting your seedlings started as well. 

Oxygen

Oxygen is necessary for metabolism and helps the embryo utilize the nutrients available to it. It also aids in cell division and energy production.

How to Do It

There’s not much about this process that is tricky or particularly difficult. But it’s good to know why it’s important and how it works. Essentially, soaking your seeds initiates the hydration process. It gives them a jump start. It won’t necessarily make or break germination, but it helps them use their stored nutrients more effectively in many cases. It can increase the rate and speed up the process as a result. 

Determine Whether It’s Necessary

Before you get started, it’s important to know which plants benefit from soaking. It won’t matter for some, but for others, it can make a big difference. For very small seeds or those bred for fast germination, soaking is a waste of time. Tiny ones can clump together, making it harder to sow them. 

This is mainly beneficial for those that are large, wrinkled, and have a hard outer shell. Some of the more common types that benefit include pumpkins, corn, nasturtiums, beans, peas, morning glories, and beets. Tropical plants also benefit from this, as they are exposed to a lot of moisture in their native habitat. 

Prepare Your Water

Your water should be at room temperature in most cases. Hot water can damage some, and we talked about the temperature needing to be high enough for germination. Room temperature or lukewarm is typically the way to go. 

When we soak tubers and bulbs, it’s common to add some fertilizer to the water. Seeds usually contain the nutrients they need, so this is an unnecessary step in the process. Adding fertilizer can result in burning, which inhibits the process. 

Fill a container with water and submerge your seeds. Letting them soak for the appropriate amount of time is important. You don’t want to leave them for too long, but you want them to soak for an effective amount of time. 

Get The Timing Right

The usual time frame for leaving them in the water is between 6 and 36 hours. If you leave them for too long, they can split, and that is undesirable. Leaving them for an extended time can also result in rotting which will render them useless. In general, the right amount of time is the time it takes for your seeds to double in size. 

Don’t Delay Sowing

Don’t allow your seeds to sit around after soaking. It’s important to have your soil prepared ahead of time. This way, you can move them directly from the water to the soil, where the germination process continues. 

Leaving them to sit around after soaking can have different negative effects depending on the environment. It can either cause them to dry out again, negating the process or cause them to rot. 

Other Helpful Preparations

In addition to soaking, there are a couple of other ways that you can prepare your seeds for faster and more efficient germination. The most common and effective ones are scarification and cold stratification. You can combine either of them with soaking if the particular plant dictates. 

Scarification

Scarification before soaking is helpful for improving germination from seeds that have a thick, hard shell that is difficult for water to penetrate. Scarification involves using a sharp tool or emery board to put a light score or scratch in the hard coating. For plants like morning glories, nasturtiums, sweet peas, and spinach, this is good to do before you soak them. 

It’s important to exercise restraint when scarifying, as it’s easy to break all the way through the shell of some seeds and damage the embryo. Ironically, the best tools to use for this tend to be nail care tools. A small-sized nail clipper or emery board is light and makes it easy to deal with delicate seeds. 

Cold Stratification

Cold stratification is another process that increases the germination rate. This typically works and is important for plants that are native to colder climates or that experience significant cold temperatures in winter. These go through a process of freezing and thawing over the winter, which breaks down the shell and helps to induce germination. 

If you’ve ever had a round of seeds turn out poorly, check to see if that plant requires stratification. I find this is often the cause of a low germination rate. It’s easy to stratify and requires little equipment. All you need is a paper towel and an airtight bag or container.

Find out before you start whether your plant requires moist or dry stratification. It will more often be moist, but not always, so check ahead of time. Check the necessary time for that particular plant as well. Typically, the farther north it is native to, the longer you’ll need to stratify. The refrigerator is cold enough for stratification in most cases. 

Key Takeaways

Soaking your seeds is a great way to increase the germination rate. Make sure that you identify whether it’s good for your particular plant and if you should pair it with stratification or scarification. By combining these processes, you’ll have tiny plants sprouting in those trays in no time!