What Every Seed Needs

Every seed has specific needs that must be met before it will even consider germinating. Luckily, almost all seeds need the same things…almost. Some seeds have simple requirements, and some are more complex, but it all starts with Water

Seeds Need Moisture

A seed can germinate and grow into a full sized mature plant without soil…only using water. Did you know that? Hydroponics proves this. So, obviously, the first thing every seed needs if it is to germinate is water.

Water starts the process of imbibation, which causes the seed to swell and activate it’s enzymes and to break dormancy. The introduction of water is essentially an alarm that wakes the seed up and tells it to get to work germinating.

When a seed is planted in dirt or a seed starting mix or any other medium other than water, that medium must stay consistently moist, at least to the depth of the seed, in order for the seed to germinate.

Seeds Need Oxygen

As living things, seeds require oxygen to germinate. Regardless of the amount of water you give a seed, without oxygen, it will not break dormancy. Even though they’re tucked away underground, seeds actually need to breathe to wake up and start growing.

The seed uses oxygen to burn through its stored energy reserves, which is a process called respiration (the same as a human beings respiration, but different), which gives it the power to push that first little sprout through the shell of the seed.

If the soil is too packed or the poor seed is drowning with too much water, it can’t get the air it needs to germinate, and it will die and rot before it ever has a chance to see the sun.

So, how does a seed that is buried under the soil or another growing medium get air?

The Correct Growing Medium

In hydroponics, the correct growing medium isn’t actually water at first. And for those who plan to plant in the dirt, seeds usually are not started in “dirt.”

In hydroponics, seeds are typically started in “starter plugs” or cubes that are made of materials like rockwool, coco coir, or peat. Once the seeds germinate, they can be moved into the main hydroponic setup.

If you plan to have your seeds grow into plants in “dirt,” which my Jeremy constantly reminds me is called “soil” not “dirt,” your seeds are best started in a seed starting mix that contains little or no soil.

I think of my seeds and seedlings as my babies. I view the initial cell or pot where I plant the seed to be the baby’s bassinet, and the seed starting mix to be the baby’s swaddling.

Not wanting to smother or squish the baby, the seed starting mix must be very light weight. It usually starts with peat moss or coconut coir. Then, perlite and/or vermiculite is added, along with a bit of lime (ground or pulverized limestone – NOT hydrated lime or builders lime!). Worm castings or well-screened, fine compost may also be included, but when everything is mixed, it must be LIGHT WEIGHT.

We feed the baby (seed) with water, keeping his or her swaddling moist, but not soggy. And then, we keep providing our babies with other necessities.

The Ideal Temperature

Baby doesn’t like to be too cold or too hot…just like your seed babies. When it comes to getting those seeds to “wake up,” temperature is the most important signal they’re waiting for—think of it as their internal alarm clock.

While most of your common garden favorites will sprout somewhere between 65°F and 85°F, you really have to know if you’re dealing with “cool-weather” or “heat-loving” plants to get the best results.

Cool-season crops like lettuce, peas, and spinach are hardy souls that can start moving when the soil is just 45°F to 50°F, but your summer stars like tomatoes, peppers, and cucumbers are much pickier—they won’t even think about sprouting until things warm up to at least 65°F or 70°F, and they truly thrive when it hits a cozy 80°F.

If it’s too cold, your seeds will just sit there and likely rot; if it’s too hot (usually over 95°F), they can actually “cook” and go into a permanent sleep. Here is a cheat sheet for you:

Warm-Season Crops

These are your “summer stars.” If the ground is colder than 60°F, they’ll likely just sit there and rot.

Cucumbers, Melons & Squash: These are the ultimate heat-seekers; they want a minimum of 60°F but thrive at 95°F.

Tomatoes: Need at least 50°F, but they’re happiest at 80°F–85°F.

Peppers & Eggplant: Minimum 60°F, but they won’t really take off until the soil is a balmy 85°F.

Beans & Corn: Need a minimum of 50°F–60°F, but prefer 80°F–95°F.

It is vital that you understand the difference between air temperature and soil temperature! When a person, website or seed packet refers to temperature, in gardening terms what they are referring to is the temperature of the soil, not the air.

Darkness or Light?

You may think that all seeds like the dark, but this is not true. In fact, there are many that will not germinate unless they can actually feel and see the sun. There are of course, others that will not germinate unless they have the complete darkness that comes with being under the soil.

Think of the seeds that prefer light as “early risers.” You know, those people who love daylight and conduct their lives in daylight. The seeds that prefer the dark are like the people who only function well at night. No matter what time they wake up, their brain doesn’t fully start clicking until it’s dark. These are the people we refer to as “night owls.”

Most of the usual garden seeds are night owls…they want to be tucked in under the soil. These include tomatoes, peppers and beans. But there are other “usuals” that must have the light, such as lettuce, celery and many flowers.

Usually, your seed packet will tell you how deep to sow the seeds. Some will say to “scatter” the seed on top of the soil and to either not cover them, only pressing them firmly onto the surface of the soil, or to lightly cover them. If the package does not say, use the Internet to find out whether your seeds are night owls or early risers.

Up Next: Germination, Emergence and Sprouting – Oh My!