Growing Zinnias

Growing Zinnias

Zinnias are a fantastic flower to grow in summer, and you can't beat an armload of these bright cheery flowers. Some of the colours that are now available to grow from seed are stunning and they come in a wide range of colours and sizes.

       Below: Zinnia elegans Queen Lime Red, Giant Limes, White Cosmos and Achillea millefolium Weser River from the gardens at Puriri Lane

Puriri Lane | Zinnia elegans 

We would have to say Zinnias are amongst the easiest flowers to grow and a perfect choice for beginners.  Flower Farmers also tend to always grow these as they are such prolific producers as well as being reliable.


As Zinnias are not a fan of cold weather, they prefer to be planted after the weather warms up a bit.  Many gardeners in warmer parts of the country are able to sow their Zinnia seeds direct, but we like to be able to get them well established before planting them out and grow them in our plastic house around 4-6 weeks before our last spring frost.   We planted our Zinnias at 30cm spacings although you can for intensive flower farming plant them as little as 23cm apart.

Zinnias love the heat, so they must be grown in full sun to produce well. We would normally use black weed matting to grow them in to keep weeds at bay and also provide that extra boost of heat although this year we did not do that and we had a bumper crop of flowers.  You can succession sow zinnias every 2-3 weeks to ensure you have an ongoing supply all summer long and well into autumn.


Visitors to Puriri Lane always ask how do we get long stems? Pinching them out when the plants are around 20-30cm in height will help you to achieve long stems. By "pinching out" the growing tip, this sends a message to the plant to throw out multiple stems from beneath where the cut has been made which will result in many more flowers as well as longer stems.  Make sure you use some fine sharp snips to do this - we find that ARS snips which you can find here are excellent for fine work such as pinching out.

As you want to ensure you maximise the numbers of flowers that are produced, you will need to ensure that you are regularly harvesting your flowers otherwise they will go to seed.

Below: Zinnia haageana | Jazzy mix

Puriri Lane | Zinnia haageana Mix


Picking zinnias at the right time when they are fully ripe is also important to ensure that you get longevity from them.  The best way to check is to hold the stem about 20cm down from the top and do the "wiggle" test.  Gently shake your flower stem whilst holding it and if it droops or bends over, it is not ready to pick. If the stems are firm and erect then they are ready for cutting.

Puriri Lane | Zinnia elegans | Cut Flower Patch

When conditioning your flowers, zinnias are what are termed as "dirty flowers" meaning they will discolour the water, so they will benefit from a drop or two of bleach in the water.

If you are not regularly harvesting your zinnias - the early morning or late afternoon is best - be sure to deadhead any spent blooms to help focus the plant’s energy into producing new flowers and not going to seed.

Below: ZInnia elegans Queen Lime Orange

Puriri Lane | Zinnia | Queen Lime Orange

Floret who of course are the experts on growing have said that many people growing zinnias in warmer climates do not get the same high percentage of double flowers and has done quite a lot of research about. Many of the breeders that Erin contacted have said that if plants undergo any stress including not getting enough water of if the temperatures are too high, they can start producing single flower, which is interesting to note if you are having this problem with your seeds.  We get the odd singles amongst some double varieties but mostly we have no problems with them.


Collecting seeds from zinnias is quick and easy, and each flower produces loads of seeds! The only thing that you will want to be sure about is whether or not your plants are hybrids or open pollinated.  Hybrid plants will not produce offspring that are true to the parent so you may well be disappointed with the outcome, so we suggest harvesting seed from open pollinated plants. 

Below: ZInnia Oklahoma Ivory

Puriri Lane | Zinnia elegans | Oklahoma Ivory

When it comes to saving your seeds, just remember that if you have lots of varieties growing in the same area they may not come trues as they can be cross pollinated by a variety of different insects and the work involved can be relatively involved as you will need to bag or cage several flower buds before they flower to prevent accidental cross pollination so that is why we tend to purchase our seeds rather than harvest them.

Below: A Bumblebee pollinating a Zinnia elegans flower

Puriri Lane | Zinnia elegans with Bumblebee

If you do want to harvest your own seeds, and do as we have mentioned previously, you will need to let the flowers dry on your plants by allowing the seeds to ripen. You will need to ensure that you select healthy plants and ones that have not succumbed to powdery mildew as this disease can transfer to the seeds.

Let the flowers air dry and each flower will turn to a dark brown colour and become dry to the touch when it is ready to harvest and make sure you do not water your flower beds beforehand as the heads will need longer to dry as the plants are drinking the water when you water them!

Place the harvested seed heads on a screen - ( we use a sieve ) so that they can dry thoroughly on all sides.  The seed heads can take up to a week to dry depending upon the amount of moisture left in the head.

Take the dry head of your zinnia flower and hit it gently onto a plate or edge of a container to release the seeds.  The seed heads are small and shaped a bit like an arrow. Occasionally you get some that will stay fixed to the flower head and you can just gently pull the remaining seeds away from the flower head. Spread the seeds out onto a paper towel and let them air dry naturally for a few days which will help to keep them fresh whilst you have them in storage.


Keep your dried seeds in a paper bag or envelope - plastic is not ideal as it sweats.  We use brown paper bags when we save any of our seeds and write the variety and date that we harvested them on the bag.  Store them in a cool but dry place out of direct sun.  You can then sow your seeds once the danger of frost has passed and the whole growing cycle can begin again.

Please note that the above content is from our own personal experience at growing Zinnias, we hope that it is of some help to you.

Below: Zinnia elegans | Zinderella Peach

Puriri Lane | Zinnia elegans | Zinderella Peach
Below: Zinnia elegans Queen Lime - Butterflies Love Zinnias!
Puriri Lane | Zinnia Queen Lime

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1 comment

  • Kay McRae

    Love the Zinnias, would love to have these in our zinnia bed as well.

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