Growing a garden that can support you and your family needs more than just good soil. You also need good seeds and you need to know how to get them to sprout. This can be trickier than you might think, especially if you plan on harvesting some seeds from your garden each year. Here’s the basics of what you need to know.
Types of pollination
Just like people, plants mix their traits with one another when they breed. In order to get a consistent plant year after year, gardeners use different techniques when developing seeds:
This is the natural way of doing things. Open-pollinated plants are genetically diverse and will adapt to your local climate over time. However, if you grow plants of similar species close enough to each other, they can crossbreed into a variety with undesirable traits. Remember that list of Brassica species? Most of them will crossbreed with one another.
Certain plant varieties are so desired that gardeners have taken special care to make sure those types stay the same. Heirloom plants are open-pollinated plants that are protected from unintentional cross-breeding. Some companies, like Seed Savers Exchange, even have documented breeding histories.
Most plants are going to be hybrids. These are species that are crossed by human intervention between two different species or varieties. These crosses focus on improving particular traits, like the size of a tomato. They grow great, but the seeds they make can be pretty bad. They may not even be viable at all. Hybrid gardeners thus have to buy new seed every year from the companies that have the original parent plants.
To summarize the important points, you will want to select open pollinated or heirloom seeds if you plan on saving seed from your garden. Hybrid seeds frequently make sterile or less productive varieties of plants in later plantings. Also, if you like a particular heirloom variety you’ll need to make sure that it doesn’t cross-pollinate with another related plant.
Getting seeds to grow
Assuming you’ve bought seeds from a seed store, your seeds should be ready to germinate. Germination is the process by which a seed sprouts into a plant. In order for a seed to germinate, it needs certain conditions. If they aren’t met, the seed won’t grow. To understand why, we need to look at the anatomy of a seed.
Most seeds are made up of three components. There is an inner embryo which contains the genetic material for the plant. Surrounding this is a layer of food that the seed uses to sprout. Last, there is a surrounding seed coat that protects the seed until its ready to sprout.
To germinate a seed, the seed coat needs to be penetrated, the food store converted to usable food, and the right signals need to be sent to the embryo to start growing. That’s where our requirements come in.
The first important condition for seed growth is water. Nearly all seed coats will absorb water and become weak through a process called imbibition. The seed coat swells up and the water activates enzymes in the food layer to feed the embryo. The presence of food and water tells the plant that it will survive if it sprouts. If there is not enough water, seeds will not grow.
There are certain types of seeds that need specific quantities of water. These requirements will match the water cycles of its natural habitat. For instance, deserts get watered in huge rain storms so many desert plant seeds require long soakings in water before they’ll even think of coming up. Plants that live in water might also need soaking. For most vegetable plants, simply keeping seeds moist for a week will keep them alive.
It is possible to overwater seeds. If there is too much water the seed can swell too much and rot before the plant can get up to speed. Whenever you water seeds the idea is to keep them moist, not soaked. However, if you’re sprouting indoors, giving seeds a soak for a little while then taking them out and putting them in moist conditions can speed the process of sprouting.
Until a plant grows leaves, it cannot take in carbon dioxide. In the early stages of plant growth, oxygen is necessary. The way that seeds get oxygen is through air pockets in the soil. This is why it is important to have soil that is loose and friable. If the earth is packed, the seeds can suffocate before they break the surface of the soil. This is also why it’s important to not walk on your garden beds.
If you have clay soil, a lack of oxygen can be common. If you plant seeds and then have a really hard rain, it can cake the clay and create an impenetrable barrier. If you mix in some of your compost you can keep this from happening.
This is the biggest variable between plants. It affects cellular metabolism and growth rates. Every species has a particular range of temperatures it likes to be in. If it is too hot or too cold, the seed will remain dormant. But there’s more to it than just keeping the temperature steady.
As with most things involving plants, it’s best to look at nature to see how it works. The outdoors is never kept at a constant temperature. There is a temperature difference between day and night. When the seed notices that this range is correct for its growth, then it will activate. That’s not to say that germinating seeds inside at a constant temperature doesn’t work, but you’ll have better results if you can discover the range that works best for your plants. Some species won’t sprout at all unless there are alternating temperatures.
Most seed packets will tell you the minimum soil temperature for a particular species to sprout. If you can fluctuate the temperature from a little above the minimum to about 15-20 degrees above it, you’ll have much higher germination rates if you’re growing indoors.
The alternative, and the easier way in my opinion, is to look at the highs and lows of temperature in your region and look for a similar temperature band, then plant outside. That being said, some people really like the challenge of growing things earlier or later than nature intended. It comes down to temperature control. For more information on some tips and tricks to do that, check out some of these free articles on our website:
Also, some seeds require a long period of cold and humid conditions to sprout. Trees, shrubs, and many perennials take this tactic. More on this in the section on stratification.
Light is necessary for some seeds to germinate, but not as many as you might think. Some species use light as a gauge to how close they are to the surface and what the temperatures might be. For instance, birch tree seeds requires eight successive days of 10 hours exposure to light to sprout! Most vegetables aren’t that finicky. In general, the smaller the seed is the closer it needs to be to the surface to sprout. Read the back of your seed packet for the planting depth and then look at the sizes of your seeds. You’ll quickly be able to gauge how deep to plant if you do this over the next planting season.
Stratification and Scarification
Water, temperature, oxygen, and sunlight may be the basic ingredients for seed growth, but other seeds are very picky. Sometimes a seed must be held at a particular temperature for a long period to simulate winter or spring. This is called stratification. Other seeds need to have their outer coats damaged in order for water to break through. This is called scarification.
The most common type of stratification the home gardener will need is cold stratification. This involves putting seeds through a cold period for several weeks to simulate winter. Perennials often need cold stratification to sprout. The old way of doing this was to plant in fall or winter and hope the seed survived through the winter. We can improve this using several methods:
Cold Frame – Plant outside in October and then a cold frame over where you planted.
Cold water soaks – Take a small jar and fill it with cold water. Put your seeds into the water and stick it in your fridge. Change the water daily for two weeks, then plant as usual. This simulates snow melt washing over the seeds. Changing the water daily prevents rotting.
Refrigeration – Soak your seeds overnight and get rid of any floating ones. Those are already dead. Take a moist paper towel, put your seeds on it, then fold it and press it between your hands gently. Put the packet into a resealable plastic bag and label it with the species and the date you put it in. Slip the whole thing into the fridge. After a month has passed, check the seeds weekly to see if they are sprouting. If they are, transplant them as usual. If they’re not keep them in there. If they haven’t sprouted by three months, plant them anyway.
Refrigeration is also a good way to jump-start spring vegetables that love the cold, like lettuce and peas. Put the seeds into moistened jiffy pellets and refrigerate them for a week or three before planting, then plant outside as normal. You should have a much faster germination rate. By speeding up germination we can grow vegetables in soil that is too cold to support normal germination and get a faster harvest. You can try cold stratification to speed germination for any plant except plants with soft seeds from sub-tropical and tropical regions. Anything that won’t sprout until May anyway doesn’t need cold stratification.
If you’re going to try and grow trees from seed, then you will definitely need to stratify. For an excellent chart on what needs stratification and for how long, read this document from the Pacific Northwest Extension: http://cru.cahe.wsu.edu/CEPublications/pnw0170/pnw0170.pdf
For plants with heavy woody seeds, scarification might be necessary to get them to sprout. The seed coat has to be damaged somehow to allow water to get through to the other layers. Frost heave often does this over winter for trees and shrubs. You can do it by rubbing the seed with sandpaper or a file until it looks dull. You can also do it with near-boiling water. Get water to boiling then take it off the heat. When it stops bubbling, put in your seeds and let them sit there until the water is room temperature. These procedures should be done just before you plant. Scarified seed does not store well.
As a last tip, soaking any seed that isn’t prepared by stratification or scarification can get a head start on germinating by first soaking it 24 hours in lukewarm water. That will considerably speed up the process of germination.
Reputable seed companies
Before we can even think about saving seeds we need to get some from a reputable seed company. As mentioned in one of the linked articles, the best ones are those that carry open pollinated or heirloom seeds and are close to your geographic area. Here are a few we’d like to point out:
Territorial Seed Company in Oregon: http://www.territorialseed.com/
Southern Exposure Seed Exchange in Virginia (grows for the Mid-Atlantic and the Southeast): http://www.southernexposure.com/
High Mowing Organic Seeds in Vermont. Sells seed all over the US: http://www.highmowingseeds.com/
Kitazawa Seeds in California specializes in Asian plants: http://www.kitazawaseed.com/
Seed Savers Exchange specializes in rare seeds from all over the world and heirlooms: http://www.seedsavers.org/
Cottage Gardener in Ontario, Canada specializes in heirlooms. Great for cold weather gardeners: http://cottagegardener.com/
Baker Creek Heirloom Seeds in Missouri also specializes in rare seeds and heirlooms for the Midwest: http://www.rareseeds.com/
To grow seedlings or not?
If you look in any seed or gardening catalog, there’s going to be a section that sells seed growing equipment. Most of it is completely unnecessary. Our ancestors had no need to spend hours hovering over mini greenhouses and adjusting heat lamps to make everything optimal for growth. Instead they paid attention to their local area and studied the natural behavior of plants and copied it.
If your goal is to become resilient in food production, then you don’t want to get dependent on seedlings and all the systems necessary to grow them. What if you can’t spare the electricity for a warming pad? What if you can get the refill sphagnum moss pellets for your mini greenhouse? When the life of you, your family, and your community depends on your ability to grow food reliably, you don’t want to be dependent on anything fiddly.
Yes, refrigeration and jiffy pellets and special fertilizers and all the rest can help out, but if you want to master gardening then you’ll need to take the plunge and try growing outside from the start. Follow the advice you’ve read in this article and take the plunge. Experience is the best gardening teacher.