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How Late Can You Plant Sunflower Seeds?

  • Amy 

How late can I plant sunflower seeds?

If you plant sunflower seeds in late spring, they should be ready for harvest by early summer. 

However, some varieties need longer growing periods. The best way to find out how long each type needs is to check seed catalogs or ask your local nursery.

The nature of sunflowers means that the plants will increase and produce many seeds. So if you want to have a bumper crop, it’s important to sow them at the right time.

You’ll probably need to start planting late-season sunflowers when temperatures reach 50 degrees Fahrenheit (10 Celsius).

If you live in an area with cold winters, you may not get as good results from sowing later.

When to plant sunflowers?

Sunflower planting times vary depending on your location.

In most areas, you should be able to get started between April and May.

You can also sow seeds indoors in March, but it’s better to wait until the soil has warmed up outside before putting them into the ground.

Soil temperature is one factor that affects how fast your sunflowers grow.

You don’t want to put seeds into cold soil because they won’t germinate properly.

But you want to make sure the soil isn’t too warm either. If it’s too hot, the seeds will sprout prematurely.

It could lead to weak plants that die off sooner rather than later.

It’s a good idea to test the soil temperature before planting.

Option 1 – Early spring: When to plant sunflowers indoors

When planting indoor sunflower plants, you’ll need to consider the length of daylight hours available during the winter months.

Your first step will be to calculate the number of days required for your sunflower plants to complete their growth cycle.

To do this, divide the total number of hours of sunlight per day by 12. It gives you the approximate number of days required for the sunflower plants to mature.

For example, let’s say you live in a location with 10 hours of daylight per day; the sunflower seedlings would require about five weeks to mature.

Once you know how many days until the end of the season, you can decide whether to buy new seeds or use old ones.

You might want to have average garden soil mixed with composted manure if you’re using fresh seeds.

Composting manure helps to improve the quality of the soil. It also adds nutrients to the mix. 

As well as improving the quality of the soil.

Option 2 – Mid-spring: When to plant sunflowers outdoors

For mid-spring, you have to choose different sunflowers that can tolerate cooler weather.

These include ‘Early Sunglow’ and ‘Sungold.’

You can sow these types of sunflowers in late February or early March.

They will need around six weeks to grow before they flower. You also need to have good fertile soil.

Option 3 – Winter: When to plant sunflowers using winter sowing

For winters, you need a dedicated sunflower bed. The best type of soil to use is sand, which allows air to circulate freely.

It would help if you also prepared the bed by adding organic matter such as compost.

You can then sow your sunflower seeds in October. They will need around eight weeks to grow.

The advantage of growing sunflowers in winter is that you can harvest them when the weather is warmer.

However, if you live somewhere with very harsh winters, you may find that the sunflowers aren’t cheerful.

They may not even survive.

In colder climates, you may only be able to grow sunflowers from November onwards.

Late summer sowing of sunflower seeds

You can choose to plant tall-growing sunflowers for late summer-like ‘Tall Sunglow,’ ‘Sunburst,’ or ‘Superbloom.’

These types of sunflowers are ideal for growing in large containers. It would be best to start planting your seeds at least four weeks before the last frost date.

In summer, healthy flowers should appear within seven weeks. However, it takes longer to produce seeds.

It means that you won’t get any seeds until the following year.

Growing sunflowers in autumn

 Autumn is the perfect time to grow sunflowers. The range of flower colors in a single flower blooms in autumn.

It is possible to grow sunflowers indoors all year round. You could grow them all year if you live in a warm climate.

However, if your home isn’t heated enough, you may find that they don’t thrive.

When you plant sunflowers in autumn, you’ll need to ensure that the ground is well-prepared for the seeds.

You should add some fertilizer to the flower head. It will help to ensure that the plants grow strong roots.

It would be best if you also watered the plants regularly.

Soil should be kept moist but not wet.

How to choose a suitable soil type?

If you want to grow a beautiful and enormous flower head, you should select rich loam soil.

The best soil for growing vegetables is loam soil. Loam soil has a high percentage of organic matter, which contains nutrients that plants need to succeed.

This soil also drains well, which helps prevent waterlogging. If you want to grow tomatoes, you should plant them in a sunny spot where they receive plenty of sunlight.

  • Loamy soil

A loamy soil contains plenty of humus. Humus is a decomposed organic material.

Humus improves the texture of the ground. It makes it easier for water to drain away.

Humus also gives the soil an excellent structure.

  • Highly porous soil

Porous soil is one of the most critical factors in growing sunflowers.

Porous soil lets oxygen into the root zone.

  • Wet soil

Wet soil is near rivers and streams. It contains lots of nutrients.

Using a wet type of soil is excellent for growing sunflowers. But you must remember to keep the soil moist.

  • Sandy soils

Sandy soil is light and doesn’t hold much moisture.

It means that it’s challenging to grow sunflowers in sandy soil. Sandy soil is on beaches or dunes.

Last words

Planting ornamental sunflowers seeds is a fun activity. But you have to take care when choosing a location.

Ensure that the soil is fertile and has plenty of room for growth. And always remember to water your sunflowers regularly.

To plant sunflower seeds later than usual, you need to wait until warmer weather.

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Amy Toliver

Hey'all I'm Amy, a born foodie and diagnosed with celiac disease 7 years ago. I refused to cave into tasteless, boring gulten free food and create my own! On my blog you'll find info & cool facts along with recipes, all on gluten free foods!