A Short Lesson on Seed Starting

We are nearing that time of year to start our seeds indoors. Today we are going to talk about what a seed needs to sprout so that we can have healthy plants to set out in spring.

Germination

Some thickly sown kale in our greenhouse. Once they are mature each plant will be moved to a larger container.

Before you start seeds at home, there are a few things you should know about germination (which is jargon for when a seed sprouts). Almost all seed varieties have different germination requirements, which can make things confusing. Fortunately, for most of the annual crops we grow in the garden the rules are basically the same. For germination, these vegetables and flowers require:

  1. Moisture (not dampness)
  2. oxygen
  3. warmth
  4. correct levels of light or darkness

Moisture

Getting the moisture right is crucial to starting new seeds. Too wet and you inhibit the flow of needed

A basic spray bottle is the best watering tool you can use for seedlings. It makes soil moist without moving things around.

oxygen, too dry and newly emerged roots will be damaged.

 

Make sure you keep your soil consistently moist. A plastic spray bottle is good for watering young seedlings because the gentle mist prevents seeds from being moved around in the soil.

Some of us may have childhood memories of soaking corn, or pea seeds before planting outside. This does aid in more rapid germination, but if you were to leave them sitting in water for a couple days, the seeds would die from lack of oxygen. It is important to recognize that seeds need a balance of water and oxygen to grow.

Oxygen

The ingredients in our seed starting mix: peat moss, vermiculite and worm castings. You can mix your own or you can buy pre-made mixes.

We all know that plants breathe carbon dioxide, but they also need oxygen for various functions. A seed needs oxygen to grow before it has created any photosynthesizing material that it will use for the rest of its life and begin breathing carbon dioxide. Plant roots also need oxygen, as the soil organisms that help plants take in nutrients are oxygen breathers.

 

To ensure proper oxygen levels in the roots, the type of soil you use to start your seeds is important. Most seed starting mixes are made of a light natural material like peat moss. This is usually mixed with nutrient rich amendments like compost or worm castings, and mineral components like perlite or vermiculite. All these combine together to form a mix that is nutritious and holds both water and oxygen simultaneously.

Starting your seeds indoors in plain dirt or with “hot” amendments like animal manures can lead to problems and poor germination. They do not have the airy properties of a seed starting mix.

Temperature

Temperature is crucial for some but not all seeds. For example, peppers are notoriously hard to sprout. This is because they require temperatures of 80-85 degrees to germinate. Any lower and the seeds won’t budge. To make matters more confusing, swings in day/night temperatures can influence their decision to sprout or not. What the pepper seed is doing, is deciding if the weather can support a full grown pepper plant, before coming out into the world. Always read your seed packet for any important information, and consider using a heat mat when starting tricky seeds.

Most seeds are not as picky. 50 degrees is a very common germination temp for the cold weather crops we want to start in February. This is easily achieved in the home.

Light and Darkness

These alfalfa sprouts have been growing in light conditions since they sprouted. Darkness is not always necessary.

Understanding light levels for germination can be tricky. Most of us have been told that seeds need complete darkness to sprout. However, most seeds will sprout in any light conditions, and some need one or the other. For example, chamomile seeds require light for germination. In contrast, most of the veggies we grow in the garden are less concerned with light levels. Covering seeds with a light layer of soil is usually enough to get them started.

 

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