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| Hydroponic indoor seed starting |
Saturday, January 25, 2025
Are there tricks to successful seed starting? What's the most successful way to start seeds?
The most sure fire I have found in germinating seeds is with a gadget called Aerogarden with the seed starting tray that has room for 72 seedlings at a time. I have almost 100% germination rate with it. I also start many seeds in the basic seed starting kits you get from the big box stores with good luck. It took some time to figure out how to have success with these kits. Here is what I have learned.
With the Aerogarden hydroponic seed starting system, I don't even have to worry about using a heating pad for the warm season crops. It is easy to take the seedlings and just plant into larger pot or directly into the garden when they are the right size for transplanting. There are a couple of drawbacks with this system-the unit is pricey and the plugs you need to buy each year are about twice the cost of peat pods. Also the seedlings can get crowded and leggy.
For other seed starting approaches, I have had the best success using a heat mat and grow light that I leave on during the day and turn both off at night. Many cool season loving plant seeds won't even germinate at the high temperatures the heat mat provides. By turning off the heat mat at night, it gives the cool season crops the temperatures they need to germinate. The warm temperatures during the day give the summer lovers the higher temperatures they need to germinate. The best of both worlds!
Another key learning I had was that you don't want your seed starting medium to be too wet. You want the medium to be moist. Sopping wet soil can cause the seed to mold instead of germinate.
This year, I have already started onion seeds it peat pots with seed starting mix and will likely do a combination of Aerogarden for the smaller warm season seedlings and harder to germinate types and peat pods for the larger seedlings.
For any system, you need to make sure everything you use is sterilized. I have an older Aerogarden seed starting system. It has a styrofoam seed starting tray. Even using a bleach solution did not remove the mold. Last year, I put the tray in the summer sun and that removed all the mold stains.
Seed starting steps
The key is starting with sterile seed starting mix, pots, containers and trays. For the trays and containers, sterilize with alcohol or bleach solution. You can make your own seed starting mix with peat moss or coir (renewable), compost, and vermiculite. Just be sure to heat the compost to at least 150 degrees to kill any pathogens before using to start seeds.
Place the seeds in the starter mix in the pots after wetting the soil or coir thoroughly from the bottom (watering from the top can dislodge seeds). Make sure to eliminate any air pockets in the soil before planting. You can lightly press down on the soil with your finger or water overhead before planting the seed. You don't want your soil mix to be completely wet, but nice and damp. Seeds need oxygen to germinate. Waterlogged soil can result in moldy seeds instead of seedlings.
After fully moist, you are ready to put them in a catch pan. Make sure any catch pan that you use has been thoroughly sprayed with alcohol or washed in a bleach solution so all pathogens are killed. Rinse well after sterilizing and before using for seedlings. I use restaurant style baking sheets. They hold many seedlings and are super sturdy.
Make sure you label your seedlings as soon as you plant them; you may think you will remember 2 months from now what was where, but likely not! Now is also a great time to start keeping a gardening journal. Start tracking what you planted when so you can review next year what worked well to repeat and what didn’t work so well to tweak.
I put my seed starts in a tray in a sunny window or under LED grow lights. Using two T8 fluorescent bulbs or grow light bulbs for 16 hours per day should provide enough light to grow sturdy seedlings.
Keep moist, but not wet, until seedling emerges. Water from the bottom so as not to disturb the seed/seedling. Pour off any standing water to discourage fungal disease. You can use a spray bottle to keep the seedling and soil damp as well to avoid overwatering or dislodging the seeds.
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| Peat pods and Aerogarden on heating mat |
Use bottom heat during the day to encourage speedy germination (turn off at night). As soon as the seedlings have sprouted, discontinue the heat. Additional heat helps speed germination and reduce the chance of mold or fungal disease. By only using heat during the day and discontinuing heat after emerging, that has eliminated the dampening off of my seedlings.
Once your seedlings have sprouted, gently run your hand over them once a day. This encourages the stem to strengthen. I tried this for the first time last year after hearing from an Extension Agent and Master Gardener that she had done studies using this technique. I did see a difference in stem strength doing this.
Another option is to use a small fan to blow on your seedlings to strengthen their stems to make transplanting safer.
Whatever you do, handle the seedling by its leaves and not its stem. This reduces the risk that you will bend over, break or crush the stem which kills the seedling.
Once the seedling is up and going, spacing them a couple of inches apart helps the plants to grow sturdy stems instead of spindly. When crowded, the seedlings race to get to the light. If they are still leggy, it is likely insufficient light. Make sure you are keeping your artificial light as close to the seedlings as possible (about 2" from the seedlings).
Don't be too worried if you have leggy seedlings. Once hardened off outdoors, they will strengthen up very quickly. You just have to be extra careful in handling them as their stems will be very fragile. The best time to transplant is when recommended on the seed packet and when the seedling has nice roots that you can see throughout the soil. Always harden off before planting. Make sure the soil is moist and the seedling is fertilized when you plant so it has everything it needs to get growing.
Your seedlings will need diluted liquid fertilizer starting 3 weeks after planting. Using a weak fish emulsion is said to help prevent dampening off. It should be no greater than half strength as these are tiny plants that don't need as much food as a full size plant.
For larger seeds, and seedlings, I start directly in their garden bed spot or pot at the recommended time on the seed packet. I always start peas and green beans directly in their garden bed spot or pot. You can grow bush type cucumbers, squash, watermelon and dwarf tomatoes in large pots, too. Otherwise larger seedlings like cucumbers, beans, watermelon, cantelope, squash and tomatoes started in a tray or peat pod will need to be transplanted into the garden bed or a larger pot as soon as they have their first set of true leaves.
Your seedling’s first leaves are not “true” leaves, think of them as baby teeth. The second set of leaves are their true leaves. They are ready to be hardened off when they have their first set of true leaves. Seedlings must be hardened and not just thrown outside. You take them out a little at a time, gradually increasing their exposure to sun and cold, only during the daytime. A week or two should be enough to harden them for the great outdoors. I try and plant when there is a warm spell and there are clouds forecasted to minimize the temperature shock and sun scald.
Be sure to keep them watered after transplanting for a couple of weeks to allow their roots to get a good foothold.
It seems I grow more and more varieties from seeds, from flowers to herbs to fruits and veggies. There are just so many fun varieties out there that you can only get as a seed! I also have saved seeds from store bought veggies that I thought were cool and tasted great.
There are great selections of herbs and veggies at nurseries and big box stores nowadays that give you many options, including heirlooms and organically grown. You can wait until spring is officially here and pick up plants that looks good at your nearby store in a couple of months. Your local gardening centers will carry what varieties are best suited for your area. This is also a great back up if your first seed starting adventure goes a little awry........
