How to Improve Germination
Starting your own garden plants from seeds is one of the best cost-saving moves you can make for your garden. But what if you can’t get your seeds to sprout reliably? Ending up with too few, or too weak or spindly seedlings can be a waste of precious time and money. So how do you get healthy, happy baby plants to start your garden right? Check out these four factors for how to improve germination and let’s get your garden off on the right foot.
What is Germination?
Germination is a fancy word for getting seeds to sprout. There are several stages that your seeds go through before you see those first little leaves poking up above the soil. First they soak up water and it makes the seeds swell. This kicks off the sprouting phase and they may split open their seed coat at this stage.
Next there is a lag phase where changes happen inside the seed getting it ready to sprout. How long this phase lasts can vary a lot from seed to seed, some varieties only take a few hours, others take a few weeks. The seeds are taking in oxygen and starting to make proteins and process the food stored in the seed.
Finally, the root and the sprout start to emerge. Depending on how deeply the seed is buried, it may take some additional time after the sprout splits open the seed to get above ground, but you will finally see something happening at this stage. Getting the conditions right at each stage in the process is key to improve germination.
Dialing in Humidity
Humidity is very important in getting your seeds to sprout reliably. Not just having enough moisture, but also keeping it at a relatively constant level. Letting your seeds or the soil they are in dry out, even for a few hours can spell disaster for a tiny sprout. The little plants don’t have enough reserves to survive without water for very long.
Use the greenhouse effect to your advantage when setting up your seed starting area. Using covered trays can make sure your seeds get the consistent humidity they need. It will also reduce the amount of watering you need to do by preventing evaporation. This can help keep your seeds from being drowned or parched by uneven watering. Make sure to check your seedlings often in the early stages. Especially if the lids get obscured with moisture, you will want to know as soon as any sprouts emerge or if any parts of the tray are getting too wet or too dry. You can use clear plastic containers as lids for planting seeds outdoors as well. Make sure to allow air flow under the lid if the temperatures in your mini-greenhouse get too hot on a sunny day.
Once you have sprouts, you will still need to keep the humidity relatively constant. You may need to open the lids to prevent too much moisture from collecting on the fragile new leaves or encouraging fungus or mold growth. But try to keep the soil moisture consistent. You’ll get the best root growth if your plants avoid drought stress for their first few weeks. When you get ready to start hardening them off, you can let them go a little longer between watering.
Maintaining Temperature
Temperature is another key factor in how to improve germination. But the temperature range you’re shooting for will depend on what kind of seeds you plant. Research the ideal soil temperatures for sprouting online or on your seed packet. Measuring soil temperatures outside can be tricky as the weather and the time of day can greatly affect the result. Using dark colored mulch or ground cloths can raise soil temperatures rapidly in the spring allowing you to plant some seeds earlier. Using shade cloth can help cool soil temperatures when planting in the summer.
If you are starting warm season seeds indoors, use a programmable heat mat to maintain the ideal temperatures to keep your seeds cozy. However, the heat mat can also increase evaporation from your seed starting trays. Check on heated trays frequently to make sure your soil isn’t drying out. Once your seedlings move to larger pots, heat mats may no longer be necessary, but they can increase how fast your seedlings grow.
It can be difficult to start cool season succession plants or fall garden seedlings in the heat of summer. Starting the seeds indoors in air conditioning or a cool basement or garage can make sure your seeds sprout and get a good start. Then they will be ready to move outside as the weather cools down for fall or winter harvests.
Maximizing Soil Contact
Soil contact is key for getting your seeds to sprout. If the seed is sitting on top of the soil, it might not absorb enough moisture to start the germination process. If the seed is buried in compacted soil, it won’t get enough oxygen or be able to get rid of the carbon dioxide it produces when it starts to sprout. The seed could suffocate or not be able to force it’s sprout through the compacted soil.
Good soil aeration can also help keep temperature and moisture in line. Heavy, compact soil can keep too much moisture around the seed and prevent it from getting enough oxygen. Soil with a lot of clay can also form a crust over the top which can be difficult for delicate seedlings to push through.
You want your seeds to be firmly pressed into the soil without being compacted. Large seeds like melons, squash, peas, beans, and corn can handle heavier soils and push through a crust more easily than smaller seeds. But all seeds benefit from well aerated soil high in organic matter. Get your soil texture right and maximize seed-to-soil contact to optimize your germination.
Getting Light Right
Most seeds want to sprout in darkness. In fact, some won’t sprout if they aren’t completely covered by soil. There are a few wildflower, herb, and greens seeds that need light to sprout, but those are the exception to the rule. Keeping your seed trays in the dark can help improve germination and reduce evaporation and temperature swings before sprouting.
However, as soon as your seeds sprout, you need to get strong light close to their baby leaves. If you don’t notice your new sprouts, even for a few hours, they can quickly grow long, skinny stems looking for light. These “leggy” seedlings will never be as strong or healthy as seedlings that grow on shorter, stockier stems. Check your seed trays often, especially when you expect your first sprouts to appear.
Although you want strong light close to your seedlings once they sprout, you have to be careful with your lighting too. If the leaves grow up and touch the light fixtures, they can burn the leaves either with heat or with excess ultraviolet (UV) radiation. Some gardeners also like to mimic natural lighting by turning their supplemental lights off overnight. This gives the plants time to rest each day. Putting the lights on a timer will keep your plants on a schedule and prevent accidentally leaving your plants in the dark.
Putting it All Together
Now you need to set up your seed starting area, or prep your outdoor beds to take all four factors of how to improve germination in to account. It can be difficult because changing one factor can impact another. Try to find the happy medium where each plant variety can thrive. It will be different for different seeds. For hearty cool season seeds, planting outside with no cover but ensuring good soil contact and consistent watering may be enough. For more delicate warm season seeds, a mini-greenhouse on a heat mat for several weeks of tightly controled humidity and temperature with optimal lighting might give you the best results.
Taking the time to dial in the right conditions can significantly improve how many seeds sprout, how fast they sprout, and how healthy your seedlings are. Growing a crop of healthy, thriving seedlings can save you a lot of money over buying started plants at the garden store. You also have more control over the varieties you can grow and their growing conditions. Take steps to dial in the four factors in how to improve germination today!
Need help finding a seed starting mix that’s right for you? Check out my blog post on How to Make Your Own Seed Starting Mix for a simple recipe to start from.
Looking for more help in getting your plants off on the right foot? Check out my Mission: Healthy Plants mini-course with everything you need to know about keeping your plants thriving from seed to harvest.
