Top 10 Principles of Growing Great Vegetable Seedlings

The principles that govern plant growth don't change, but understanding them will change your experience with seed starting. If you have ever planted seeds only to be dissappointed when they fail to germinate, or spout only to damp off and die? Maybe you can keep them growing but they look floppy, leggy and pale. How does anyone get great seedling starts? This video covers 10 key things to get right when planting seeds indoors.
1. Start with good quality seeds.
Pick seeds with the potential to grow into the plants you need. Looking for disease resistance? Pick seeds that meet those needs. Do the same with flavor, timing and yield, keeping your end use in mind. Grow what you want to use. Seeds can last several years, but old seeds can germinate unevenly. Some seeds last longer than others.
2. Choose the right growing materials.
Choose pots or trays that are shallow (seeds don't need lots of depth), even (you want light to reach all your seedlings evenly) and clean (to avoid disease).
Choose a growing medium that is light (so seeds won't have difficulty emerging), airy (so you get plenty of oxygen to the roots), disease-free (so you won't introduce disease), and has both the ability to retain moisture and well as drain off extra water effectively.
3. Plant seeds correctly
Two common problems with planting seeds are too dense and too deep. Seeds planted too deep won't have enough stored energy to emerge, or will take too long.You might water them so much while waiting for them to sprout that they rot. Many seeds need light to germinate and if they are planted too deep they can't get it.
Planting seeds densely prevents plants from reaching their full potential as the seedlings have to compete for resources. They will grow smaller and stretch more. Some of the seedlings will die or you will have to thin them which is a waste of resources if you have good quality seeds. The risk of disease is also increased as dense seedlings struggle to get good airflow.
4. Water Correctly
To water correctly you need to find the "Goldilocks zone" for each type of plant. Generally you want moist soil but know your seeds needs.
Water gently to avoid washing seeds away by using a mister or water bottle sprayer until seeds have emerged and are stronger. You can bottom water after the seeds have grown enough roots. As seeds grow they will use more water so adjust watering to match as they grow.
5. Control your humidity
Seed starting kits often come with a humidity dome to prevent evaporation while seeds are germinating. Take them off after seeds have germinated so that condensation on the dome does not lead to problems like damping off, and so seedling won't stretch. Try to plants seeds that germinate around the same time together so you they emerge together and the domes can come off at the right time.
6. Give seedlings enough light
Supplemental lighting is essential for top quality seedlings. It is almost impossible to get adequate window light in the winter months for seedlings that want the light they would have in summer. Good lighting is on at least 14 hours a day directly over the plants with lights that are at least 5000k. Place lights close to but not touching the seedlings.
7. Get the temperature right
You need to know the needs of your seeds. Generally seed germination temperatures are higher than growing temperatures. Use heat mats to help bump the temperature up 10-20 degrees. Peppers are happy to germinate at 90 degrees, but lettuce and brassicas want to germinate and grow at much lower temperatures. Once germinated most seeds no longer need the heat mat.
8. Feed your plants
Plants in small containers have limited resources, so make sure you are taking care of their needs. Feed plants lightly at first and after they have germinated and have true leaves. Use a diluted plant food. Frequent light feedings are better than infrequent large feedings for producing nice stocky seedlings.
9.Transplant seedlings
Bumping your seedlings up to bigger containers gives your seedlings room to grow bigger and healthier. This is done after you have at least 2 sets of true leaves.
10.Time the planting of your seeds
Determine your frost date and plant your seeds relative to this date paying attention to how much time is needed for each seed to grow. Onions and leeks take 10-12 weeks to grow. Peppers, eggplant, and tomatoes want 6-8 weeks to grow before the last frost, cucumbers, melons and corn only need 4 weeks, and pumpkins and squash only 2. Lettuce, kale, peas and cabbage get planted early but get set out before last frost dates. Know your capacity from grow lights, to greenhouse to garden and make a plan!

[@annmc3878]

For home gardeners, small trays for seed starting is good. Because we usually not growing 100 tomato plants. I find that the corners of trays seem to dry out faster than the middle cells, so I pay attention to the corners. I like the tip that I heard this year, you can put something under the tray to raise it up rather than always moving the lights up and down.

[@iowabackyardfarmer2952]

Excellent suggestions! Those smaller trays are great for doing small batches. I find I have to watch my corners too, and good point on the lights. Mine are easily changed but if they weren’t this is a great idea. Thanks for taking the time to share your thoughts and experience!

[@NicoleSmithGardening]

I just love listening to you guys talk seeds! 😌🌱

[@iowabackyardfarmer2952]

Thank you!!!

[@villanella]

i discovered your channels a few days ago and i love it. incredible thorough and great knowledge, delivered in a simple and understandable - often humorous way. you guys are great!

[@iowabackyardfarmer2952]

Awesome, thank you!

[@C3Voyage]

Nice, a lot of good info. Some things I do are a bit different, but still great stuff.

[@iowabackyardfarmer2952]

Thanks! I looked up and subscribed to your channel! It looks like you have great gardening experience too! There are so many cool things to experiment with. Thanks for the stuff you post and thanks for stopping by with an encouraging word!

[@vickiperkins476]

Lots of wonderful information. Thanks so much 😊

[@iowabackyardfarmer2952]

Glad it was helpful!

[@lcfarmer9352]

What do you guys have started so far? I started some habaneros Lemon Starrburst, and Lesya peppers, along with onions last weekend. Planning a few more peppers this weekend, and the rest the weekend after that. Tomatoes I was planning to wait until early-mid March.

[@iowabackyardfarmer2952]

We have started lemon grass, lavender, rosemary, thyme, parsley, chives, spearmint, peppermint and oregano started in herbs. Im ordering onions from Dixondale but they would be in now too. I’m trying a bunch of perennial flowers that are good for herbal teas, hummingbirds or bees that are planted early. I did some more yesterday. Also pansy, petunias, vinca and lobelia for hanging baskets went in early.
Peppers so far I have Carolina reaper, habaneros, Scotch bonnet, Ghost pepper Leysa, Aji peppers and some of my cayenne. If it took over 80+ days to mature after transplanting then I started them early. I planted my hanging pot peppers and tomatoes this week and some of the medium ones like guajillo, pasilla, chile de Árbol, Tabasco, hot wax, Thai, Hungarian wax and Havasu. Most of my sweet peppers are only 60 days to harvest from transplanting so I’ll probably plant them up over the next few weeks too. Sweet ones in about 2 weeks. Tomatoes I will also wait for until early-mid March. The Leysa I planted is doing great. My habaneros are growing slow. The lemon Starburst sounds cool! I’ve also planted some lettuce, chard and yesterday some kohlrabi that like the cold and can go out early. Today I’m planting peas inside to give them a quick jumpstart and then I’ll put them into the garden about March 10. It won’t be long now! I just potted up my rhubarb starts yesterday. They will sit under the lights until I need the space and then go out to the greenhouse with the bareroot strawberries, raspberries, and blackberries that I ordered and will pot up in mid March!