8 Pro Tips For Getting Seeds to Germinate

By Maegen Lewis, MS Plant Science, Utah State University

It can be very rewarding to sow seeds and notice a couple weeks later that tiny leaves have begun to emerge. You can sense the hope of your new little plants as they absorb that first bit of light. Whether you are starting your seeds inside before the snow has melted or patiently waiting to seed outside when spring has sprung there are a few basic things you need to know that your seed packet may not tell you!

Identify Season Length

The first thing to do is get to know your region. The two things you’ll need to find out are: Frost dates in your zip code, and the USDA hardiness zone for your city. If you never get frost in your area then you’ll need to identify the dates that you start to get more than 10 hours of sunlight and the dates when you start to get 10 hours or less. This framework will provide your season length and determine when you should start your crops and which seeds will mature and produce flowers or fruit before your season ends.

Direct Sown vs. Indoor Seeding

After you have selected what seeds you want to grow, you will need to decide whether to direct seed outside or start your seeds indoors. Direct sown simply means you plant your seeds directly into your garden or raised bed soil when the soil temperature matches the germination temperature requirement on the seed packet. Starting your seeds indoors means you plant seeds inside in pots or trays and once the plants are large enough you transplant into the garden. This method is especially helpful for those with a short growing season who want to get a jump start on their garden. The seed packet may recommend one method over another, but most seed types can be sown with either method if you provide the right conditions!

Media

When starting your seed indoors, there are a lot of different soilless medias you can choose from. Unlike the soil from your garden that is primarily made of sand, silt, and clay particles, ‘soilless media’ is made up of a mix of peat, coir, perlite, vermiculite or a few other materials. This artificial soil provides nutrients, and a good balance of water retention and aeration that is needed for healthy roots when growing plants indoors. Using soil from your yard in small containers is not recommend since it will not drain as well without a large depth of soil below to draw the water down. Any soilless media will work but if you feel nervous about your selection, potting or seed starting mixes are your best bet.

Container

The next item you will need for starting seeds indoors is a tray or pot. Again, there is a wide variety of options from peat pots for individual seeds to plastic seeding trays that are reusable and can fit hundreds of seeds. A few plastic cups can work well too! Don’t worry too much about the “ideal container.” The most important factor of your chosen container is that it has drainage, so punch a few holes in those plastic cups if necessary. Drainage is important because it allows excess water to drain out, preventing your roots from rotting. A lesser consideration is container depth. Larger seeds typically need deeper containers up to 4” for something like a pea or tomato plant. Larger seeds typically have deeper roots and need a bit more space to stretch out their legs. Only have deep containers? Fill them up a little shallower, no need to buy a different container for every type.

Seed Depth

Seed depth is typically listed on a seed packet but if it isn’t, a good rule to follow is a depth 2 times the diameter of the seed. Seed so tiny you can barely see it? Sow it on the surface of your media. To prevent seeds from moving around before they establish roots, press seeds into the soil surface with your finger, or sprinkle a very fine media over the surface. The ultimate fan favorite media for this is vermiculite, which not only secures the seed, but allows light through and prevents water loss from the seed or soilless media.

Water

Water is what gives life to your seed. If seeds dry out even once they will fail to germinate. When watering, you will want to keep a few things in mind: First, always soak your media all the way through. Second, a very gentle surface watering or below tray watering is critical during the first couple of weeks to not disturb the seed. Below tray watering is done by placing your container in a shallow pool of water and removing it once the surface of your media is wet. Third, is maintaining high levels of humidity which can prevent seeds and media from drying out. For indoor seeding, any clear material can be placed over your tray to build up humidity. Once your seeds have grown a set of leaves you can remove or vent the covering.

When seeding outside, water is just as important and your seeds may dry out even faster due to wind and increased light. Frequent light irrigations are recommended to keep your soil surface wet, especially for seeds sown on the surface or at shallow depths. Rather then using plastic, you can use peat or coir or some other media that has high water retention to prevent your seeds from drying but will still let light through.

Light

Some seeds require light for germination, some are indifferent, and others won’t germinate if they are under light. However, all seeds will need light as soon as their leaves have emerged. Pay attention to your seed packet or the Halden site information that will tell you whether your plant requires light or darkness to promote germination. Whether starting seed or growing young plants the most important thing to remember is that plants need light for 12 to 16 hours a day. If your light doesn’t include a timer, consider investing in one or just using an alarm on your phone.

The spectrum of light that you use is also important. Although plants can grow under cool-white or warm-white alone, they will often be spindly or stunted plants. Full spectrum lights will best mimic the sun and produce the strongest plants. The two most common choices are LED and fluorescent bulbs which will give off less heat and be more cost efficient than many other types.

The height of a light above the tray is also important. Closer lights result in more absorption. Too close can excessively heat up your plants causing leaf burn. LED should be 8-12” away and fluorescent lights should be hung 5-6” above your trays. As your seedlings grow you will need to accommodate the new plant growth and raise the height of your lights. Always check to see if you have even coverage over your seed tray. One LED bar may not cover the entire tray evenly so a second may be necessary.

Temperature

It is important to pay attention to germination temperatures as temperature is one of the key components to triggering germination. Lower temperatures will slow seed growth or prevent germination from occurring while higher temperatures may accelerate seedling growth but result in weak plants. Germination temperatures of 50-60 often mean the plants will prefer cooler temperatures after they have emerged between 55 and 70. Plants with warmer germination temperature requirements of 65-80 will most likely prefer temperatures between 65 and 80 after they have emerged.

Although plants are miraculous and can grow in suboptimal conditions, following the tried and true methods above will result in higher germination rates and ultimately stronger, healthier plants, which means more flowers, fruits, vegetables and herbs for you! Each plant will be a little different and the fun is in getting to know them. Find the ones that you love whether it is for their ease of growing or their finicky nature, the success of each crop is so rewarding. I hope this guide will help to fuel your seeding success!