What Does A Seed Need?
What Does A Seed Need?
Originally published March 1994
Seed is the least expensive component of gardening, so it makes good sense to buy the best quality seed you can obtain.
Start With The Seed Packet
The packet usually gives you a great deal of information about how to grow the seed successfully. Whether you purchase the seed packet from a retail store or a mail order catalog, the packet is the first place to look for guidance.
The Miracle of Seed
Seed is the botanical equivalent of an egg. It contains the very beginnings of a plant, along with enough “food” to get the seedling started. But a seed won’t sprout and grow unless four things are provided: light, heat, air and water.
Light. Once sprouted, all plants need sunlight to grow. But some seeds germinate better in darkness, and some seeds germinate better in light. Again, the seed packet should indicate this, or a good garden reference book will tell you. Germinating seeds that like darkness is simply a matter of covering them with the growing mix or germinating mixture you sow them in. For complete darkness, put the seed flat in a black plastic bag after you have watered it. This will also help retain the moisture for germination. Check the flat every few days. Once the seed has sprouted you can remove the bag. The seed packet will usually indicate how deeply to sow the seed, but that is more important if you are sowing them directly into the garden than if you are starting them indoors in a germination flat. Generally, sow seed one or two times its thickness.
For seeds that germinate better in light, simply sow them on top of the growing medium and do not cover them with the medium. Normally, indirect sunlight is all that is needed, however, you may want to invest in some grow lights that you can use once the seed is sprouted. This is important in areas where the late winter and spring months are often cloudy. If you put the germination flat in direct sunlight there is a danger of the medium drying out or the sprouted seedlings getting burned from the heat and intensity of the sun.
Heat. Just like an egg, seed needs warmth to germinate. An ideal germinating temperature is often given on the seed packet. If it isn’t given, a normal room temperature, or a little warmer, is usually sufficient for most seed to germinate. Professional growers usually prefer bottom heat for germination. At home, using heating mats that are available through mail order catalogs or at some garden supply outlets can provide this. Bottom heat is not essential for success, but it is a good idea to use if possible. Remember that you are concerned with the temperature of the growing medium, not the air temperature. Placing germination flats on a cold floor, near a door or window, will lower the medium’s temperature even if the air temperature is sufficient. If you are simply providing basic room heating, elevate the flats off the ground so that the air can warm the entire flat. Some boards held up by blocks, or a table or bench should be adequate. The top of your refrigerator is a good place, too. Protect your flats from drafts by putting plastic sheets around the germination area or in some other way keeping drafts away from the flats.
If you are sowing seed directly into the ground, it won’t sprout until the soil warms. Sow seeds into the garden after the last frost date in your area.
Air. Seeds, like plants, need air to breathe. The most common way that seeds and plants are kept from the air they need is a result of overwatering or a lack of drainage. This is why it is necessary to provide loose growing medium that allows excess water to drain away. If a seed is surrounded by water it will drown from lack of oxygen. The same is true of tender young roots – they need air to develop, and too much water will kill them.
Water. Seed requires water for germination. When the seed absorbs water, the seed swells and that is the first physical sign that germination has begun.
Water needs to be provided to the seed as uniform moisture. The sowing flat or container should remain uniformly moist for 7 to 14 days while seeds are swelling and beginning to germinate. To maintain uniform moisture, wrap the sowing container in plastic, or use the plastic dome on a seed starting kit. It is very important not to let the medium around the seed dry out.
After germination and when the seedling has used up the food stored in the seed, the water carries nutrients that plants need to survive.
Seeds come in an almost infinite range of sizes. Some are extremely small, the size of dust, such as begonia seeds that add up to about one million seeds per ounce. Others are quite large, such as pumpkin seeds, sunflower seeds, and the jumbo seed of the coconut. Large seeds are easily handled when sowing, but small seeds can be difficult to see and control when sowing.
There are several ways to handle small seed more easily and to keep them from falling in clumps or piles when sowing. One easy way to handle small seeds is to mix them in a jar or bowl with white table sugar. Most seeds are dark, so they contrast with the white sugar and are then easier to see. Mix the seeds into the sugar by stirring or shaking. This will help distribute them more evenly throughout the sugar. You can then use a spoon to scoop out the mixture and shake it over the growing medium for more even sowing. The sugar won’t hurt the seeds or seedlings, and it will dissolve into the soil when you water. There are also seed sowing implements available that allow you to pour your seed into them (usually into a deep groove with a small opening at one end) and have better control as you sow than if you were to simply shake them out of the packet. A piece of paper folded in half can give you a deep groove to pour seeds into so you can see them, and then you gently shake them onto the medium by tapping the open end with your finger.
If you are sowing seed directly into cells in a flat or into a growing container, be sure to put more than one seed in each cell. It’s possible that not every seed will germinate.
After your seeds have sprouted in germination flat, you need to continue to provide light, heat, air and water to keep them growing. When the second or third set of leaves appear, you can transplant them to growing flats so that they will have more room to grow.
Seed, Glorious Seed
Growing a plant from seed is a wonderful way of achieving a strong sense of accomplishment, and gives you a heightened sense of pride.