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How Late Can You Plant Zinnia Seeds – Revealed

No doubt, zinnias are everyone’s beloved flowers. But cultivating them could be quite tricky, and you may wonder how late you can plant their seeds. 

I’m completely obsessed with zinnias and have been planting them for quite a while now. That’s why I would advise you that you should cultivate their seeds in the spring after the last frost. But somehow, if you’ve missed the best weather, you can still plant them later in the summer season (8 to 10 weeks before the first expected fall frost). 

In today’s post, I’ll tell you about:

  • How late can you plant zinnia seeds?
  • How long does it take for zinnias to mature from seed?

How late can you start zinnia seeds?

3 small piles laying on a weathered wood backdrop. The first pile is zinnia seeds and labeled "seeds". The second pile is one single seed half emerging from chaff, labeled "seed in chaff". The third pile is of light colored plant chaff and is labeled "chaff".

I’ll only talk from my personal experience! Zinnia seeds are ideally planted in the spring, after the last frost. It’s the time when the soil has nicely warmed up for your precious little flowers. 

But if you’re a lazy and forgetful person and have missed the best planting window, you still stand a chance! You can sow zinnia seeds later in the summer. This time, you need to make sure to plant them 8 to 10 weeks before the date of the first fall frost in your place. 

To be honest, you need to grab this opportunity with both of your hands. 

Why? Well, timing is very important as it allows the seeds to germinate and helps the plants to make a mark for themselves before the arrival of colder weather.

Once you plant the zinnia seeds in the right weather and they start showing some growth, they will be able to endure cold temperatures like a boss (Provided that you keep feeding them nicely). 

How long does it take for zinnias to mature from seed?

Even if you’re a bit late in planting your zinnia seeds, you can still make amends and see good results in the coming days! Here’s a general timeline for you:

1. Zinnia Seeds Germination (5 to 24 days)

Welcome to the first exciting stage- Germination! This is the time when zinnia seeds sprout and start to show their magic. It usually takes about 5 to 24 days. That’s my calculation! 

The first leaves (Called cotyledons or seed leaves) emerge to support early photosynthesis.

2. Seedling Stage (2 to 3 weeks)

The next part is the seedling of the zinnia plant. 

This happens when tiny zinnia plants poke their heads out of the soil. It takes 2 to 3 weeks (If the plant is healthy). 

They grow their very first set of true leaves (They are different from seed leaves, which I mentioned above). 

At this point, the baby zinnias need special care. They are delicate (Like newborns) and need the right amount of water and sunlight to grow strong (Not too much or not too little, just in balance). 

3. Growth of Zinnia Plant (4 to 6 weeks)

After zinnia seeds sprout and become proud seedlings, they start their gradual growth process. This phase lasts for around 4 to 6 weeks. 

During this stage, the zinnia plants keep getting bigger. They develop a stronger root system, which goes deep into the soil and suck up water and nutrients from the ground.

While above the soil, a whole different party is going on! More leaves and branches start to grow. They play a very important role in soaking up the sunlight to make food. 

I can’t stress this fact enough that zinnia plants need the right conditions if you want the growth phase to go well. They love sunlight. So, give them a sunny spot. Water is vital, too (To keep the soil moist all the time). 

And not to forget! The type of soil matters as well. It should be well-draining and nutrient-rich.

4. Flowering (6 to 12 weeks)

A bright orange zinnia blossom with a backdrop of purple and white alyssum

Once zinnia plants have grown nicely, they enter the phase of flowering. This takes 6 to 12 weeks (After the seeds first sprouted).

You should know that different types of zinnias take different amounts of time to start flowering. Some varieties are quick bloomers. Others might take a bit more time!

The flowering stage is the grand reveal of all the hard work that you’ve put in. Just at this moment, the tiny buds on the plant start to open up and reveal a bunch of colors (Like red, pink, orange, and yellow). 

Hey, wait! Your task isn’t done yet. You need to keep watering the plant and taking care of it just the way you did before. 

5. Full Maturity (10 to 12 weeks or more)

As time goes by, your beloved zinnia plants keep growing and producing flowers during the entire season. 

When I talk about “full maturity,” I mean the point when the plants have reached their maximum height and are giving you the most flowers. 

This usually happens around 10 to 12 weeks (Or more) after the seeds first start growing. At this stage, your zinnias have grown tall, and their branches are filled with lots of beautiful blooms. This is when your garden looks most colorful. 

Here’s a tip from me to you! If you want your zinnias to keep blooming and looking gorgeous, you should go for “deadheading.” 

Now, what is deadheading? It’s just a fancy word for removing the flowers that have finished blooming. 

When you do this regularly, your plant will keep making new flowers. More or less like a haircut! Right? 

What is the fastest-growing zinnia seed?

If you’ve missed the best planting window for zinnias, you don’t need to be worried! I’ve got this. How? I will tell you about the fastest-growing zinnia seed so that even if you’re late, you can expect quick blooms!

So, here it is- “Benary’s Giant.” It is known for its large and vibrant flowers that give you a wonderful surprise in a shorter time frame compared to some other zinnias. 

But wait! You need to provide this variety with good growing conditions (Such as well-draining soil, full sunlight, and consistent watering). And that’s about it!

Ending Thoughts!

Now that I’ve spilled the beans on how late you can plant zinnia seeds, I believe that you’re fully prepared for this task. 

Now go ahead, get your hands dirty, and start planting. Soon, you will see a garden full of zinnia magic, and a beautiful scent will absolutely mesmerize you.