YAY! It’s almost seed starting season! Notice I said-- "ALMOST!" At least here in North Dakota!
Before we get into the thick of things, let's review the four most common mistakes to avoid...
#1. Starting Too Early!
Starting seeds too early is all too common. Pay close attention to recommended planting dates for your location. Study the growing information on your seed packets or posted by your seed source.
Pro tip—better to start a bit late than too early! Starting too early runs the risk of root bound, leggy plants that are running out of nutrients.
If started too early the risk is being forced to transplant under less than ideal conditions ‘cuz your plants are stressing. The other option is to try to hold them longer for favorable weather. If your plants start out stressed out, they'll have a HARD time living up to their potential. STAY PATIENT!
Find your average last frost date by click this link and typing in your zip code. Compare this information to your experience, if you’ve lived in your location for a while. In our experience it's a good practice to add a few days or a week to the estimate.
Your goal is abundance—your most productive season. That doesn’t necessarily mean the earliest tomato in the neighborhood. Most of us are not market growers trying to be the first to market with those prized tomatoes. Getting the timing right will maximize production because you'll be transplanting the healthiest seedling at just the right time.
If ya’ gotta start SOMETHING to scratch that itch, start some slow growing flowers—like petunias! Or grow a tray of microgreens for an early salad! 😂
#2 Over- and Under-watering!
Pay attention—water will slip you up if you don’t take care. This has to be just right!
Seeds need to be moist while germinating but not too wet. Our best tip is to keep those trays covered with clear plastic wrap or a humidity dome until your seeds germinate—especially if using heat mats!
So critical. If the soil dries out while your seeds are germinating, they will die before they ever have a chance to emerge.
Pro-tip: Moisten your soil before filling your trays. We like to use a 5-gallon pail with a lid, fill about 2/3 with your soil mix, moisten with 8-12 oz of water, depending on how dry your starter mix is. Put the lid on and let sit to absorb the water. Then mix and check to see if it’s moist enough.
Add more water if needed. Replace the lid and let it sit and absorb for a few minutes. Check again, mix and repeat as needed until the soil is damp but not wet—kind’a like damp sand. Soil should still have the ability to flake and flow-- not clump or smear.
Now fill a starter tray with the moistened mix one at a time and-- plant immediately-- before the surface has a chance to start drying out.
After planting, immediately cover the tray with plastic wrap (the kitchen kind) or a humidity dome to keep in the moisture. Or you can slide it into a clear bread bag. Now wait for the seeds to germinate!
You should not have to add any moisture before the seeds germinate. If you find you DO need to remoisten, use a mist to ensure you don’t dislodge tiny seeds or make the surface too wet. Alternately, add ¼” of water to the bottom tray (if using a tray with no drainage holes) and let the cells soak up the water.
Remember-- watch carefully! Once the seeds germinate, remove the plastic wrap or humidity dome immediately and get them the light they need! If you miss it, your seedlings will get leggy in low light conditions very quickly!
After removing the plastic and putting the seedlings in a well lit location, check daily and ensure the soil does not dry out. Water on a 'just enough' basis. Do not water too much! Bottom watering is preferable, keeping the tray moist but not soggy. Overhead watering is doable... being careful not to knock over fragile seedlings.
#3 Not Enough Light!
Seeds generally don't need light to sprout and emerge. The exception is some flowers seeds that are specifically labeled to be surface sown and 'need daylight to germinate'. However, actual daylight hours is sufficient for germination and no grow lights are required until AFTER your seedling begin to emerge from the soil.
Now ya gotta take action! You don’t wanna do all this work and skimp on something so simple… Without enough light, your plants will get leggy and weak.
Simply put, consider these two decisions: 1. type-- fluorescent or LED, and 2. spectrum-- full spectrum vs. cool blue or dual band.
If you're focusing on starting plants for your garden, you won't go wrong with a full spectrum grow light, either fluorescent or LED, with a color temperature in the blue range-- 5,000 - 7,000 Kelvin (K)-- to promote leafy green foliage. Click here to read a deep dive into lighting options.
Seedlings require more light than most mature plants. Once they germinate, they are developing their first true leaves and root system. To get off to a strong start seedlings require a lot of energy. They are “light hungry”. Think of a child on a growth spurt constantly saying, “I’m hungry!”
Seedlings need a high volume of light energy measured in photons. Mimic a plant's natural environment, giving them 12-16 hours of light. Setting a timer will help to ensure there is a regular rhythm to their 'day' and 'night'. Keep the lights positioned just above the top leaves to feed them well.
IF a sunny windowsill is your best option, use white paper or tin foil to surround your trays and reflect the incoming light back onto your plants. One idea is to use cardboard and tape the white paper or tin foil to it as backing. A lined cardboard box with half of the top and one full side panel cut out and facing the window works well!
This strategy will ensure you make use of all the light available to you. And the reflected light will be bouncing from all directions, helping to reduce plants leaning and stretching towards your window for more light.
#4 Over Use of Heat Mats
Most seeds germinate well at room temperature. Pay attention to the temperatures for best germination. Consider the crop you're growing and whether you’re trying to start a cool season plant or a heat lover?
I had a customer call me and tell me her onions were not coming up. As I asked questions I learned she had them on a heat mat. She had planted them two weeks prior to calling me. I told her to take them off the heat mats-- onion seeds don’t like it hot. A few days later she called back and said that her onions were coming up!
Onions and lettuce seed have a built in thermal protector. They will NOT germinate if the temperatures are too hot. That's why it can be difficult to start lettuce seeds for succession planting in summer heat! And it's why those onion seeds would not germinate on her heat mats.
My advice-- don't use a heat mat unless you're sure you need it. A heat mat can help if:
- Your seed starting room is too cold (like mid-60s°F or lower)—your seeds may take too long to sprout.
- You’re growing seeds that need higher temperatures to sprout (e.g. eggplant, rosemary) or like it warmer (e.g. peppers, tomatoes)
If you’re running behind and need to get some annuals established ASAP, only use a heat mat IF the seeds you're starting germinate best at warmer temps! Heat is not necessarily gonna speed things up for you.
Here's to getting off to a running start!
Our best to you,
Theresa