If you want to grow beautiful, eye catching flowers then zinnias are a great option. For beginners they’re ideal as they don’t need a lot of attention and there’s not much that can go wrong with them
They also come in a great variety of colors that you can’t helped to be charmed by them.
So I’m going to will take you through growing zinnias and how to do it without running into any problems. I’ve grown zinnias many times over the years and so feel well placed to give you some tips on getting them to grow successfully.
Choosing the Right Zinnia Variety
Zinnias come in lots of different shapes and sizes. There are the likes of dwarf varieties that work well in pots through to giants that look amazing in your garden beds.
Popular Varieties:
- Dwarf Zinnias (e.g., Thumbelina): Perfect for pots and small spaces as they only reach around 6 to 12 inches tall.
- Medium Varieties (e.g., Dreamland): Great for garden beds, they grow 12 to 18 inches tall.
- Tall Zinnias (e.g., Benary’s Giant or State Fair): Excellent for cutting gardens, growing up to 3 feet or more.
It doesn’t matter which type you choose as there’s a zinnia that will work for every garden. But you should be matching the variety to your garden or space that you have available. And of course how you want that garden/space to look.
When to Plant Zinnias
Timing is everything. Zinnias love the heat and need warm soil. So when you plant them you need to take this into consideration:
- Soil Temperature: Ideally zinnia seeds should be planted when the soil temperature is around 70 to 80°F (21 to 27°C). Cold soil will stop them growing and delay the germination.
- After Frost: Plant them outdoors after the frost has gone. Zinnias don’t like the frost at all.
If you’re starting seeds indoors then you should begin with them around 4 to 6 weeks before the last frost happens. Then you can transplant the seedlings outside once it gets warmer (and will stay warmer). Just be careful when you’re transplanting then though as zinnias can be a little picky when it comes to be moved.
How to Plant Zinnia Seeds
It’s fairly simple to plant zinnias from seed. These easy steps will get you started:
- Soil Preparation: Loosen the soil with a garden fork and mix in compost to give to some extra nutrients. Zinnias like soul that drains well and is a little acidic (pH 5.5 to 7.5). But they will still be ok will most types of soil as long as it isn’t soggy.
- Planting Depth and Spacing:
- Sow the seeds around a quarter of an inch deep.
- Space the seeds or seedlings about 6 to 24 inches apart. Although it will vary depending on the variety of zinnia you’re planting. This distance apart is important as it will leave enough room for the air to flow and stop diseases like powdery mildew.
- Watering: Keep the soil moist but not soggy. When they’re young zinnias really like a lot of moisture but as they get older they don’t mind as much. You should always be watering at the base of the plant though as getting water on the leaves can cause fungal problems.
Thinning and Transplanting Zinnias
One your seedlings have reached around about 3 inches tall then you should thin them so there’s enough space between all of them for the air to flow and they can grow easily. Thinning them also means they shouldn’t get overcrowded and you’ll avoid diseases potentially spreading.
Here’s a good tip: pick the strongest looking seedlings and then get rid of the ones that look weak or leggy. If you hate wasting plants then you can also transplant those ones you would have so scared into pots and grow them.
If you started the seeds indoors then you should harden off the seedlings first before you transplant them. Slowly expose them to the outdoors over the course of a week or so, giving them a few hours of sunlight every day.
Caring for Zinnias
Once they’re planted you need to look after them the right way so they do well.
Watering
Zinnias do best with consistent watering that goes deep. This even more important in the summer when it’s hotter.
Water them early in the morning as it lets the leaves dry out throughout the day and will stop mildew from growing. And try not to water from overheard for the same reason. Instead use a soaker hose or drip irrigation to keep the leaves dry.
Fertilizing
Zinnias don’t need a lot of fertilizing but a little bit will certainly help. Especially if the soil you’re growing them in doesn’t have quite enough nutrients.
Use a general purpose fertilizer when planting and then add some organic fertilizer as the plant grows.
Mulching
Mulching really helps with zinnias. Just a 2 inch layer of organic mulch will mean the soil holds onto moisture and keeps the roots cool.
Mulching will also stop weeds from growing and soil splashing which can carry disease to the leaves.
Deadheading and Pinching for More Blooms
Zinnias really do well when you prune them. Regular deadheading is super important for getting more flowers.
Removing the spent flowers makes the zinnias send their energy to making new buds rather than producing seeds. So you get lots of new flowers.
How to Deadhead:
- Simply snip off the old flower heads just above the nearest set of leaves.
- If you’re hoping to get cut flowers then cut the long stems of your zinnias. The more you cut the more flowers you get.
If you want your zinnias to get bushier then pinch them back when they’re around 6 to 8 inches tall. This should encourage them to branch out and you’ll get a bigger, fuller plant with more flowers.
Common Pests and Diseases
Zinnias can be affected by pests and diseases, just like most plants. Watch out for:
Pests:
- Aphids, spider mites and whiteflies can target zinnias, especially in hot and dry weather. They’re fairly easy to deal with though – just spray them with water or use insecticidal soap.
- Insects that help, like ladybugs, are going to be a real help. They will prey on the pests that hurt your zinnias so use them if you need to.
Diseases:
- Powdery mildew is common, especially in humid areas or when the plants are overcrowded. The best way to prevent it is to water at the base and make sure the air is flowing properly around the plants. That comes down to spacing them apart properly.
- Leaf spots and bacterial wilt are less common but certainly not unheard of. If you notice any then you’ll have to remove the affected plant quickly so it doesn’t have a chance to spread.
You can help keep your zinnias healthy by clearing up your garden and not watering from overhead.
Maximizing Zinnia Blooms
If you want your zinnias to flowering all year round you can help by:
- Pinch back early growth so you get a fuller plant that also flowers more.
- Cut often! Zinnias love to be cut. So the more flowers you take the more your zinnias will produce.
- Extend the season: Sow seeds every few weeks and you’ll get flowers coming all throughout the summer.
Harvesting Zinnia Seeds
Zinnias are really good for saving the seeds. Let the flowers dry out completely and then collect the seeds so you can grow them the following year.
Although be aware that hybrids won’t always produce true to type flowers. But if you’re feeling adventurous then this can be a fun way to see what flowers emerge the next season. It can keep you guessing and be exciting to see what you get.
Final Thoughts
And there you have it! Growing zinnias is t hard and you get some beautiful flowers at the end. Being so low maintenance means you can enjoy your garden and spend less time worrying about them!