How to grow delphiniums in your garden. You can get started with seeds, purchase a plant or take root cuttings. Delpiniums are easier to grow than many think!
You can easily bring height and grandeur to your cottage garden with a few Delphiniums. Add them to your borders, beds, and the cutting garden. The Magic Fountain series delphiniums are bred to grow shorter and are perfect for cutting and arranging.
My cottage garden gets a boost in July from these beautiful tall spires of blooms. (when they bloom is determined by your gardening season) Some claim Delphiniums are difficult to grow but so far I have found them easy.
The delphiniums in my Entrance garden get full sun most of the day while the delphiniums in the side garden get some afternoon shade. The delphiniums in the Secret Cottage Garden in the back get all-day hot sun and they bloom well there too.
Don’t be put off growing them if you don’t know how they will do in your conditions. Just give them a try and find out for yourself! You may be pleasantly surprised.
Delphiniums attract pollinators such as bees, butterflies and hummingbirds and are resistant to deer and rabbits. Though everybody knows if they are hungry enough they will eat just about anything in your garden.
All of the delphiniums in my garden were started from seed. They have been dug up and divided, cuttings taken from them, and seeds collected to start more. Growing delphiniums is not complicated at all.
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Where do Delphiniums Grow Best
We have cold snowy winters and dry, warm summers. Delphiniums need a cold winter to be at their best. The website where I purchase my seeds has a map showing where delphiniums grow well. Where You Can Grow Delphiniums
The New Millennium Delphiniums are my favorite because of how well they perform in my garden. If you don’t wish to grow them from seeds then you can buy plants here: Annie’s Annuals
Many folks are familiar with the Pacific Giant series or the Centurions. All are beautiful.
Generally, delphiniums grow well in zones 3-8. In areas where you get 95+ degree summer weather, they prefer a bit of afternoon shade. But that being said many of my delphiniums are in full sun. One summer we consistently had over 95 degrees and they did fine. They just bloomed out and started to go to seed much faster than usual.
I also had a friend that grew them in zone 9b and hers were beautiful. She just made sure they got afternoon shade. As I said before don’t be afraid to try them even if you do not have the ideal conditions in your garden.
How to Grow Delphiniums
To be truthful, I don’t treat Delphiniums any different than the majority of my cottage flowers. Plant in soil full of organic matter like compost or well-rotted manure. It should be free draining but still hold moisture well.
Delphiniums do like plenty of water, so if you don’t get summer rains (we don’t), give them at least an inch a week. Most soaker hoses or drip systems will tell you how long to leave the water running to accomplish that. Mulch helps retain moisture and keeps roots cool.
You will need to protect Delphiniums from wind, heavy rain. You will need to stake them to prevent the stems from snapping, they are top-heavy and the stems are hollow.
The delphiniums in the photo above are supported by one of my DIY Obelisks, you can build one yourself! Though I built this one as a tomato support, I decided to use it for this delphinium. The obelisk is 8 feet tall so you can see how big this delph is.
Feed delphiniums with a liquid organic fertilizer every other week. I dilute it to half strength. Delphiniums are heavy feeders so extra fertilizer is needed. I usually don’t fertilize most of my plants in the ground as the soil is nutrient-dense.
In Fall, I dump tons of composted chicken debris from the hen house around all the gardens. This keeps the garden beds rich and well-draining. No further fertilization is usually needed during the growing season but I make an exception with Delphiniums.
Pests & Disease
Here we have dry summers and don’t usually have to deal with much powdery mildew. If a problem does show up I use this spray, but sparingly.
Slugs can be a problem in early Spring as the Delphiniums are just sprouting. Sluggo Plus works well and the one treatment is usually all that needs to be done. Though both of the products are rated for organic gardening I still limit their use. Though accepted for use does not mean it won’t harm the good insects we do want in our gardens.
How do you Keep Delphiniums Blooming
After blooming you can cut off the flower stalk just at the side shoot flowering stem (if there is one).
If you look to the right of the blooms in the photo below you will seed a side shoot with tiny buds on it. Once the main bloom is beginning to lose its petals on the bottom of the plume, cut down to just above that side shoot.
The variety I grow doesn’t keep blooming all Summer though the shorter varieties will keep blooming longer if you cut them.
I don’t cut mine at this time as then I lose the entire plume that is still looking beautiful and I want it that in my garden.
After the small shoots finish blooming cut the main stalk off at the base and sometimes you can get a re-bloom if you have a long enough garden season. I usually do not have long enough.
So instead of cutting off the stalk…..
…let them go to seed.
To let them go to seed do not cut off any blooms, just let them develop seed pods and either collect the seed when it is ready or let them drop to the ground around the parent plant. Plants coming up from seed won’t always come true, meaning they can be different colors than the parent plant. To get true clones of the parent you must take cuttings.
To collect, once the seed pod is dry and starting to crack, I hold something under the pod, like a small paper bag or envelop, then cut the seed pod off and let the pod and seeds fall into it. Set them aside in the paper container to completely dry. Then separate the seed out from most of the chaff and store them in a small baggie in the refrigerator until it is time to germinate.
Do Delphiniums Grow Back Every Year
Yes, in the right conditions. The ones I show in my photos I have been growing for 10+ years. They have been coming back bigger and better each year.
I have read that in warmer zones you should treat them as an annual. But that has not been my experience.
How to Grow Delphiniums from Seed
Click on over to my entire post on How to Start Delphiniums from Seed
Have you been inspired to try growing Delphiniums? They are worth it!
Special note: All delphiniums are considered toxic and parts of the plant and flower may cause severe discomfort to humans and animals if eaten. Gloves should be worn when working with delphiniums, contact with the foliage can result in skin irritation.
I wish you all Happy Gardening!
- Grow delphiniums from seed or buy plants
- Plant in well-draining rich soil
- Delphiniums like 6 hours of sun daily, provide summer shade in hotter climates
- Give 1 inch of water per week, more if the temperatures are above 90 degrees
- Feed with organic fertilizer once every other week
- Dead head or cut for bouquets to keep some types blooming
- Cut back to base for a possible re-bloom
- Propagate by cuttings, root division or saving seeds.
Most say that Delphiniums do best in Zone 3 through 7 but I am in Zone 8 and they grow well for me. I also had a friend that grew beautiful Delphiniums in Zone 9 with afternoon shade.