Plant Seed Basics

In my last post, Plant Seeds – Getting Started, I explained what a seed is and discussed different types of seed such as heirloom, open pollinated and hybrid. Today I’ll discuss the storing of seed and give you some suggests for getting a wide variety of seed. We’ll also look at the germination process – what is germination and what happens during germination.

Where Do You Get Seeds

Your own garden may be a good place for seeds. In a separate post I’ll discuss the process of collecting seed.

There are many seed companies you can use. Most of the well known ones sell vegetable seeds and annual flower seed. A few also sell some perennials. Stokes Seeds is a company I have used in the past.

If you want the more unusual perennials you will need to visit a specialty seed shop such as BotanyCa which specializes in species.

Another good source for seed are social media seed exchanges. People on GardenWeb used to host seed exchanges in the fall. An organizer would receive seeds from various people and then send everyone new seeds. Check Facebook Gardening Groups for similar seed exchanges.

Some plant organizations host seed exchanges for their members. The following are great for perennials, especially rock garden plants.

• Apline Garden Society (AGS)
• North Ameerican Rock Garden Society (NARGS)
• Ontario Rock Garden & Hardy Plant Society (ORGS)
• Scottish Rock Garden Club (SRGC)

Many specialty plant societies also host seed exchanges.

If you are thinking of buying organic seed you will be interested in this post: Organic Seeds – Why Buy Them?

How Long Will Seed Last?

That is an easy question with a complex answer. The oldest seed that has been germinated and grown to a full sized plant was 32,000 years old. Keep in mind that the arctic permafrost kept the seed alive, and that special techniques were needed to germinate it. But it is still an amazing story.

The longevity of seed depends on the type, quality of the seed at collection time, and storage conditions. Some seed lasts 6 months if stored moist, and dies very quickly if dried out. Other seed can be easily stored for 10 years in your fridge and it will still germinate.

Most of the seed a gardener would plant, will be viable for at least 3 years, and many types would still be good after 5 years. My 5 year old tomato seed germinates just fine.

Storing Seed

There are two types of seed. One group likes to dry out and stores best when dried out completely. Another group of seed needs to stay moist until germination. A drying of as little as a month or two will kill the seed.

Seed That Likes to Dry Out

This represents 98% of the seed you will encounter.

Store seed in paper or cellophane packets – not in plastic where it rots. Keep them in the fridge. The air in the fridge is fairly dry and cold which is perfect for extending the life of seed. I put the packets inside a jar with a loose fitting lid. If any of the seed is not perfectly dry – they will continue to dry in the fridge .

Some people suggest adding a drying agent like milk powder, rice or silica gel. There is no harm in drying the seeds too much so drying agents can’t hurt the seeds, but I have never bothered to use these products.

Seed That Needs To Stay Moist

Many of the ephemerals from North America, like Trillium grandiflorum, are in this category. I don’t know of any vegetable seeds that are in this group.

These are best stored in just-moist vermiculite, in a plastic bags. They don’t live long and should be germinated as soon as possible.

The Germination Process

This will be a general overview description of the germination process.

The mother plant makes the seed and through various means it gets spreads around until it is lying on the ground. Nothing seems to be happening, but inside the seed there is all kinds of chemical activity. One of the first things that happen is that water is absorbed through the seed coat. The water activates various enzymes to start creating new chemicals. Some of the food is used to grow new cells. It is all very complicated and as a gardener we don’t need to understand it in detail. It is however important to understand that certain chemical processes must take place before there is any visual change in the seed. These changes can take days or years. Each species of seed is different.

At some point, all the changes that need to happen have been completed, and the seed coat cracks open. The baby plant now starts to grow a root using the food stored in the seed.

Making the root first may seem odd but what the baby plant needs most right now is water. There is lots of food in the seed, but very little water and roots allow it to get more water.

Once the roots start to grow, the seedling starts making leaves. In some cases, like a bean plant, the process of making roots and stems happen almost simultaneously, and quite quickly. In other seed, like a peony or trillium, it takes months to form roots and then several more months, or even a year before leaves are made. Most plants make the leaves a few days after starting root growth.

The first leaf or two of most seedlings looks nothing like the parent plant. These first leaves are temporary leaves to get the plant going. Once they are photosynthesizing and making food for the plant, the seedling will make leaves which look a lot like the leaves on the mature plant.

Just like any baby, the seedling is very vulnerable in these early days. If it survives a few weeks or a month there is a good chance it will grow into an adult plant, especially if you are taking care of it. Chances in the wild are not nearly so good.

This video shows the germination of bean seed which is typical of many seeds. Water is absorbed and then the root starts to grow. A little while later the leaves develop.

If you can’t see the above video, use this link: https://youtu.be/pB4ASdELBbQ

Here is another good video that shows the germination of a pea seed.

If you can’t see the above video, use this link: https://youtu.be/eDA8rmUP5ZM

Seed Dormancy

Seed Dormancy is a development phase which seeds go through after being released from the mother plant. It increases the chance of survival for the seed in nature. For example, most seeds will not germinate if conditions are too dry. This makes a lot of sense from the seeds point of view. If the environment outside the seed is dry, the seedling would die if it germinated, so it is much better for it to go dormant and wait for better conditions.

Seed dormancy can be quite complex and every seed seems to have different environmental requirements for it to germinate. I’ll have a more detailed look at these in my next post. It is important for the gardener to understand seed dormancy so that they know how to handle the seed to make it germinate as quickly as possible. The next post in this series Seed Dormancy Explained goes into the topic in more depth.

For more detailed information about seed dormancy have a look at this post Seed Dormancy – Are Seeds Really Dormant?

Double Dormancy

Some seeds, such as peony and trillium, have a condition called double dormancy. If you plant the seed in the garden it will take two years before you see green leaves above the ground. Many references claim that the seed needs two cold periods to germinate, but this is not true.

Both peony and trillium seed will germinate warm but it takes several months for this to happen. Germination is defined as the emergence of a radicle (ie root) from the seed. Once the root is several inches long, the seed needs a cold treatment to cause the green leaves to start developing.

This so called double dormancy is really more like single dormancy requiring one cold period. for more information on Double Dormancy have a look at Double Dormancy In Seed – Does It Exist.

Double dormant seed is probably not the best seed for beginners to tackle.

More Seed Videos:

If you can’t see the above video, use this link: https://youtu.be/icB9HrqdQqU

If you can’t see the above video, use this link: https://youtu.be/VvGrIAkcv5k

If you can’t see the above video, use this link: https://youtu.be/dhL57pqnHHQ

References:

1. National Geographic – 32,000 year old seed brought back to life: http://news.nationalgeographic.com/news/2012/02/120221-oldest-seeds-regenerated-plants-science/