When planting sunflower seeds, tuck them into soil between 1 and 2 inches deep. Space them roughly 6 inches apart. Soil temperature and moisture influence how long it takes for sunflower seeds to germinate, but in most cases you should see sprouts in 7 to 10 days.
Too much or too little water is the most likely reason for seeds not germinating. With too little or no water, seeds remain dormant. With too much water, seeds become susceptible to rot or infection from soil-borne fungi (also referred to as "dampening off").
If soil temperatures are just right, sunflower seedlings will sprout up in 10 to 14 days. Growing sunflower seeds requires space. To start sunflowers indoors, plant three seeds per each 3- to 4-inch peat pot.
Sunflower seeds need stretched seed skin (scarification), then soaked warm water (40-50 C) for 25 minutes. Then the process of germination, next sowing in place of exposed to direct sunlight, and only then planted as well as cared for.
Sunflowers are mainly sown from mid-April to the end of May. They are an annual plant and will flower in August.
Place one seed in the divot and cover it with soil. If you have extra seeds, you can put 2-3 in one hole and then trim off the two weaker seedlings. Water the soil gently to help settle it. Sunflower seeds of most varieties should be planted about 18-24 inches apart, as they will grow to be quite large.
Some sunflowers are annual and survive only one season, and others are perennials that will return every year. All perennial and annual sunflowers produce brilliant flowers that are a highlight of any late-summer garden.
Sunflowers and Light Requirements
Sunflower seeds do not require light for germination. However, when grown indoors in pots, the plastic wrap is removed at the first sign of germination and the uncovered pots are placed in bright, indirect light.
Sunflowers are fast reproducers, and one plant can create dozens of others. Plant seeds about an 1 inch below the ground. Germination occurs quickly, usually between 5 and 10 days, but spring crops produce more plants than summer crops. Spring crops are planted in April and May.
The narrow end of the seed is where roots will emerge, so putting this end down saves the plant from having to right itself in the ground. Place the sunflowers 1 to 2 inches deep, point-down, every 6 inches or so, and then cover them up.
Sunflower seedlings should be watered daily so the soil is moist but not soaked. As the sunflowers become established, they can be watered once a week. This watering is infrequent but it should be a deep watering that uses several gallons of water.
The first step to any sprouting is to soak the seed or grain. In fact, you should do this to all your seeds, grains and nuts. Yup, you read right, soak 'em, for 1 ½ to up to 24 hours before you eat them raw or cook them.
The ideal spacing in rows for giant sunflowers with large seed heads is 20 in. apart. If you plant closer, you might get taller stalks but smaller heads.
Pick a full-sun location: 6 to 8 hours a day is ideal in a location protected from the wind. Provide fertile, well-drained soil amended with good compost. You can also add a granular, slow-release fertilizer. Sunflowers have large taproots that can grow deep in the soil.
Keep the paper towels in a plastic bag.
Put the damp paper towels in a plastic bag. Check on them once or twice a day, and continue once the seeds have sprouted. Typically, you'll see sprouts emerge from most of the seeds within 48 hours. Once this happens, move on to planting the seeds.
The fastest germinating seeds include everything in the cabbage family – bok choi, broccoli, kale, cauliflower etc, and lettuce. The slowest seeds to germinate are pepper, eggplant, fennel, celery, which may take 5+ days.
The allelopathic characteristics of sunflowers are toxic to some plants, potatoes being one of them. This process inhibits germination and can stunt the growth of potatoes. They also compete for nutrients in the soil. Potatoes should be planted well away from sunflowers to avoid them affecting one another.
While most varieties will germinate at a wide range of temperatures (between 41°F (5°C) and 100°F and (38°C)), the optimal soil temperature for sunflower seed germination is about 77°F (25°C). Read on to learn all about when to plant sunflower seeds.
There are pint-sized sunflowers that grow just a foot tall and giant varieties that reach for the sky, but you don't need a big garden to grow sunflowers. These classic summer bloomers can be planted in plastic pots, fabric planters, or even buckets.
Once your sunflowers have died back completely and the backs of the blooms are brown, it's time to harvest. You'll also notice the seeds are plump and somewhat loose. Cut the stalk with sharp scissors or pruners, about one foot down from the flower head, and place in a container that can catch any loose seeds.
Number of holes x Germination rate = Number of Plants
Let's start with 72 holes and one seed each that has a 70% germination rate. You would multiply 72 by 80%, and get roughly 57 sprouts. In this case, you can plant 2 to 3 seeds per hole and you'll probably experience maximum success.
Now is not the time for sentimentality. Crowded plants not only discourage growth, they encourage pests and disease. Crowded seedlings shade each other from the sun. As they get larger, it only gets worse.
You can plant sunflower seeds directly into the ground after the danger of Spring frost has passed and the soil is thoroughly warmed (soil temperature of 55 to 60 degrees F). This is from mid-April to late May in the Northern United States. Sunflowers can be sown directly into the ground.