How To Grow Sunflowers From Seeds In Pots. If you live in cool or cold climates, wait until the chance of last frost has passed before sowing seeds or planting seedlings. While you can plant sunflower seeds in doors in pots filled with peat, the easiest way to grow them from seeds is by sowing them right in the soil in the spring.
If your garden has quick draining soil in it, ensure that you work compost into the ground in the area that the sunflowers will be growing. For more information, check out my article on how to do a soil test. This will help with moisture retention.
In the middle of spring, about 4 weeks before the last frost has gone, fill small clean pots with clean compost, or soil and water them.
You can then sow the 12mm deep on their sides. 4 dos and don’t for potted sunflowers Once seeds germinate (10 to 14 days), pinch out weakest plant, so you have one per pot. Cut the head off the plant leaving about 6 inches of stem.