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My delphiniums are up and growing - what next? Part Two!

Wanganui, New Zealand

Dowdeswell's Delphiniums has had a Company Forum page for 5 weeks or so but I'm finding it really difficult to start any conversations about growing these plants so I'm repeating my last post on the company forum page in this perennials forum. Perhaps this is the best place for it anyway. What we're trying to do is to glean information about how delphiniums are grown across a range of climates, what problems are faced by gardeners and how these are overcome. We will then, with permission, add this information to that already on our web site. The aim is to have as comprehensive a range of growing information available to gardeners as possible - but for this we need your input. Who's game?

There's also a bribe - a free packet of hybrid delphinium seeds to anyone who contributes.

Who sprays their delphiniums? What with?

Delphiniums attract few pests and diseases. Some folk have problems with army caterpillar and slugs can be a problem early in the season, but neither of these pests are likely to devastate the plants entirely. Careful inspection for caterpillars in the spring can prevent the majority of damage from cut worms. If molluscs are likely to be a problem then placing a few slug pellets actually on the crown of the plant in fall and again a couple of times in very early spring should deal to these. Mulching with something sharp like sawdust will help keep them away too. Do remember though, slugs like delphiniums just as much as hostas, which is a lot. Always put slug pellets down before you plant new delphiniums.

Powdery mildew is minimized by keeping the plants well fed, watered and mulched. Remember to give them plenty of space too, so that the leaves have air around them. Warm, humid weather encourages the disease so make a pact with your local weatherman! A healthy New Millennium Delphinium rarely gets powdery mildew. SA sulphur based preventive spray applied when the plants are six inches tall, again when knee high and maybe once more as the flower spike forms will go a long way to preventing powdery mildew

So, who has problems with pests and diseases in delphiniums? What do you do and what would you advise gardeners in your area? Any takers?

Image New Millennium "Pink Punch"

Thumbnail by dowdeswell
Calgary, AB(Zone 3b)

The only pest or disease that affects delphiniums in this northern climate is "delphinium caterpillars" (or more formally, delphinium leaftier, Polychrysia esmeralda). This is a moth whose caterpillars feed in the growing tips of delphinium, monkshood and larkspur, causing distortion of the foliage and buds as they feed on both. It's very easily treated without resorting to pesticides, simply by squashing the caterpillars within the leafy growing tip with your fingers. (Those who are squeamish can wear gloves!)

This message was edited Mar 31, 2012 9:17 AM

Richland, WA(Zone 7b)

Here in WA I had problems with Earwigs when I first planted Delphiniums, but now that I am watching for them I can control them. Aphids also get on them, but are easily removed with homemade spray (dish liquid, cooking oil and hot pepper sauce)

Wanganui, New Zealand

Thanks for your comments.
Both these comments are in line with other reports we have. No need to resort to chemicals. A great plus.

Jo, Re the earwigs: We have trouble with them eating pollen in our breeding and seed production houses and have found the best solution to be providing them with comfortable home in the form of rolled up newspapers which we place every couple of metres along the rows. We then simply do the rounds of the earwig hotels in the mornings every few days, empty them by tapping on the ground and squashing the evacuees. They soon diminish and only need periodic attention. This method may not work so well in a garden situation. How do you control them?

I'm surprised about the aphids as we have had no problems whatsoever here in New Zealand over the twenty years or so that we've grown them. We do have aphids on other plants though. Maybe they are different species.

Interestingly we don't have problems with caterpillars. The caterpillars we have survive only long enough to ingest about a quarter inch of delphinium leaf before poisoning themselves. I'm please we don't have your species over here either.

Anyone have anything else attacking your delphiniums?



Image New Millennium "Royal Aspirations"

Thumbnail by dowdeswell
Long Beach, CA(Zone 10a)

In my zone and climate, Delphiniums are a "hit or miss" plant.
I normally grow the Pacific Giants and Magic Fountain strains. Both do well if planted in the fall and providing we have a "normal" winter. This past winter was far from normal and my PG's set flower spikes back in February when they were about a foot tall...thus frustrating me to no end because I was depending on them to be blooming the first week of May (as is normal) for our annual garden tour. Normally they're big and lush and 5 to 6' tall or taller. This was a whacky winter, spring came too soon, so maybe next year things will be better !
Most Delphiniums here don't like our hot and humid summers so I just treat them as annuals. RARELY do I have one that returns the following spring.
The prime pest I have with them is cutworms, but I use the Ortho cut worm pellets and it works fine. WIND is also a colossal bummer. Snails and slugs are easily controlled with Sluggo.

I see the dark blue and light blue "belladonna" flower stalks at flower stands and am wondering how they grow them so tall. Mine never get any taller than about a foot. Do cut flower growers have a secret source for the strains they grow ?

Salem, OR(Zone 8b)

I feel like my yard/climate must be the perfect place for growing them. I'm going on my fourth year, and I've never had any pests. They grow large. They bloom for 6 weeks May-June, and then bloom again in August. The delphs in full sun do much better than those who only get about 6 hours of sun per day. I have a couple that are planted in a rose hedge, and they aren't doing as well. They seem to get black spot on the leaves. I am going to move them next week. I love delphiniums so much, and I need to get more. I enrich their soil with compost annually and feed with a slow release general purpose fertilizer.

Salem, OR(Zone 8b)

In terms of my climate, zone 8b, it is semi-maritime. Wet winters and springs. Then Zero humidity in June, July, august. And usually zero precipitation July and august.

Kiowa, CO(Zone 5b)

I love delps. . The only problem I have is of the four legged variety, (deer love them), any suggestions other than what I did in the pix below? My second pix is grandiflora in blue and I love the fact the deer have yet to bother with them and they are beginning to reseed about which is a big +.
In another garden I had here in colorado, they were great. I had so many varieties and I can't ever remember having the deer problem altho they strolled the garden often.
I have not found any problems with critters on my delphs, not any diseases. They just grow like crazy. I'm located southeast of Denver, (at 6800feet), where we get a record 300+ days of sunshine a year and precip. is 15" annually. During the growing season I make sure they get approx. 1" of rain or watering a week. After bloom in June, I cut them back and get a second bloom at a lower height of approx. 12-18" (on the elatums). My grandifloras bloom all season, (deadheading is a must for great continual bloom).
I love making country bouquets from my garden and delphs are a favorite to add, or should I say they used to be my favorite to add.

pix #3: country cottage is my gardening style. Kathy.

Thumbnail by warriorswisdomkathy Thumbnail by warriorswisdomkathy Thumbnail by warriorswisdomkathy
Wanganui, New Zealand

Yes, Longbeach would be very marginal to keep them as a perennial because of the warm winter temps although I would expect the New Millenniums to do better than the Pacifics. We'll send you some seed to try. There are many species of belladonna that may be in the flower stalls and they can look very similar, some will grow much shorter than others. However, you have a very small diurnal temperature ranges so it is likely that plant height will be affected by this too. Were the belladonna in the flower stalls local? If so can you find out what specie? Variety?

kosk0025 - some varieties get black spot more than others and it is often more prevalent on the light blues. It is spread by water. Do you sprinkle?

warriorswisdomkathy - There are no sprays registered for deer are there? Pity. You have a great climate for delph. If you guys want to send me an email with your names, pseudonyms and addresses I'll send you some free seed


Terry Dowdeswell
Dowdeswell’s Delphiniums Ltd
692, Brunswick Rd
Wanganui 4571
New Zealand
Ph 64 6 3421733
Email: [email protected]
Web Site

Richland, WA(Zone 7b)

I just found this photo from last year. I love the bright blue. It is coming up already, and I hope it is as pretty as last year.

Thumbnail by JoParrott
(Arlene) Southold, NY(Zone 7a)

In the past I've ordered from Graceful Gardens. They do carry many of your delphiniums. My problem is that they very seldom return for the following year. I suspect it may be the summer humidity or heat.

Magic Fountains does well here but, of course, it's not my favorite.

Royal Aspirations is my favorite and has done best for me but still I can't get it to live more than three years.

Thumbnail by pirl Thumbnail by pirl Thumbnail by pirl
Hannibal, NY(Zone 6a)

Oh my gosh, Jo. How beautiful! Do you have a picture of the one to the right of the blue one blooming?

Richland, WA(Zone 7b)

OK, Polly- feast your eyes on these! From last year. The mauve ones are "Dusky Maidens" from Spring Hill nursery.

Thumbnail by JoParrott Thumbnail by JoParrott Thumbnail by JoParrott
Caldwell, NJ(Zone 6a)

I have been trying to grow Delpheniums for years with almost no success. I am interested in the newer varieties in the hope I can have some success.

Hannibal, NY(Zone 6a)

Oh, be still my heart, Jo! WOWSER!

Western, WI(Zone 4a)

Terry, I have grown your delphs for yrs. here in Wi. Purchased seed from you to start them. No pests or deer so far!
But of course that can change over night. Don't think I have any pics. from last yr. to post.
Will look later.
I am thinking about ordering seed again as you sent me a very nice e mail detailing your seed.
Thanks for the update.


Marshalltown, IA(Zone 5a)

I have a weird story here.....I am a VERY new gardener......So, the winter of 2011, I decided to winter sow....set out my milk jugs in Jan., (we are in zone 5a here) and started winter sowing coneflowers, lupines, poppies, and a couple country mouse hostas.....

Of course, the cones went crazy .....seedlings everywhere, lupines too, no poppies, and one hosta.....I planted them all in my garden, and last year, I thought "hmmmm, what is this? A weed". I didn't pull it, thank gosh, and the most beautiful blue flower came out of it......Here is was a delphinum! I must have gotten mixed up in the coneflower seed. I would like to say I babied it, but it was really ignored, just watered it along with everything came up this spring, and is twice as big as last year......

It is truly a beautiful, I guess I can wintersow them.....I didn't this year because my little garden is full, but I would like to do so in the future....

This message was edited Apr 7, 2012 9:57 AM

Salem, OR(Zone 8b)

That's a great story, sm! Surprises in the garden are absolutely the best. I cherish those flowers the most. You must have great soil, too. (they most important thing in any garden)

Western, WI(Zone 4a)

Here's some of mine

Thumbnail by Maxine Thumbnail by Maxine Thumbnail by Maxine Thumbnail by Maxine Thumbnail by Maxine
Salem, OR(Zone 8b)

I love them all, Maxine, but especially image #2! And your property/views/gardens look amazing in image #5. Gorgeous, thanks for the thrill! Mine are coming up all over the place. I will have blooms in about 6 weeks.

Western, WI(Zone 4a)

Oh thanks. I used to work in Salem at the state dept. many yrs. ago. Loved living in Oregon.
Do you save seed from your dephs.?
If you do, may I beg some from you?
I need to purchase some from Dowdowells in N.Z. They have the most gorgeous dephs. that I have ever seen.

Have a great Easter, Maxine

Thanks Melody for downloading the pics for me!
This old lady appreciates it.

Salem, OR(Zone 8b)

I don't save seeds from my delphs.....I should though! I'm going to order from Dowdeswells next year, too.

Wanganui, New Zealand

Whoa! sorry for missing so much. There are some fabulous photos you have posted there. It's just great to see them grown so well.

Piri: I would expect Royal Aspirations to at least match Dark Blue Magic Fountains for longivity so I'm surprised that it your experience it did not. Then again warm, humid weather will reduce their lifespan.

sm4657: Yes, winter sowing delphiniums works well. I know quite a few of our customers winter sow. I wish I could - but our winters are far too warm and the seedlings would either damp off or be eaten by slugs and snails.

There are free packets of seed available to all participants so far so if you haven't mailed me your address please do so now. Dmail is ok. I'll close the offer on this thread now though :-)



image - Double Innocence

Thumbnail by dowdeswell
Wanganui, New Zealand

What I'm really interested in now is to see all the different stages of growth that there are among the the Dave's Garden community.

Here in New Zealand we have them at every stage possible from seedlings just emerging to plants in full flower. However, we've had such an atrocious summer that the second growth will be lucky to arrive by winter (June)

Images - a mauve picotee and seedlings growing with flowering plants. These have been grown indoors for trial purposes

So, DO you have images of your growing delphiniums?



Thumbnail by dowdeswell Thumbnail by dowdeswell
Salem, OR(Zone 8b)

Gorgeous, and I love the macro views---you must have a nice macro lens. I love my macro lens (a Nikon) that I received for my birthday last summer. I can't wait to photograph my delphiniums with it soon.

(Arlene) Southold, NY(Zone 7a)

Beautiful photos, Terry. Those tall blues are to die for!

Western, WI(Zone 4a)

Terry, would love to take pics. of my delphs now to show you the height of them, but I can't post any thing here on Daves after I down load them from my camera.
Don't know whats wrong as I can post pics on e-mails and other web sites, so go figure!!!

Terry, how do the cream colored delphs. grow for you? I have tried the seeds 2x and nothing that I could set out. Don't know if it is me or what?


Marshalltown, IA(Zone 5a)


Since many of us plan on planting delph seeds and have difficulty, what is the best way to sow them....maybe some of us are doing it wrong....

Any suggestions would be the way, your delphs are gorgeous!

Richland, WA(Zone 7b)

I am anxious to get my free seeds- :=))

Wanganui, New Zealand

Ok, some answers

I have a Canon 600D with a standard 18mm to 55mm lense. I also have a 200mm zoom. The large files allow effective digital zoom which gives the macro effect

Maxine: reported results from the creams lately have been mixed. Creams are certainly weaker seedlings but no shows are not expected at all. We're looking at alternative crosses for cream for next season

Re the sowing of delph seeds - there are many methods that produce successful results and people have their favourites. We supply our instructions with the seed and these can be found here

There is much more info here

Where there is a good winter freeze and snowfall, sowing directly on the ground, under light mulch in early winter can be a good way to go too.

Jo, have your seeds arrived yet? Let me know if they are not there by the end of this coming week



Image - Royal Aspirations

Thumbnail by dowdeswell
Richland, WA(Zone 7b)

Terry, yes, they came yesterday-thanks so much. They are in the fridge fow awhile until I decide how I will sow them.

(Arlene) Southold, NY(Zone 7a)

The seeds arrived today. Thank you so very much. I'll be reporting on their progress.

Kiowa, CO(Zone 5b)

Thankyou, thankyou Terry, I got my seeds this morning. Might it include the rose colored one above?

Albany, ME(Zone 4b)

Well, hello!

I believe my climate, zone 4a is ideal for delphs, but I have spent literally decades figuring out how to deal with pests. You asked for images of how delphs are doing. I have right now everything from about to bloom belladonna and summer skies to lots of 4 inch high plants I ordered late from Graceful Gardens. Hopefully all will get established and I can send some images next year. Here is the pest story.

Fungus - I love the Dowdeswell web site and am using he mancozeb/copper and sulfer regimen. Seems to work fine.

Slugs - This is what destroyed so many delphs over the years until I learned about copper rings. I tried plain copper (purchased at Home Depot.... not at a garden store. Amazing price differnece) rings, but I kept stepping on them. Now I wrap the copper around a half tin can and fasten with paper clips. It's important to use a half, not a whole can, so the ring can be lifted off in late fall. If it's not, then snow will collect in the can, thaw, and freeze to ice, certainly delaying the plant, if not killing new sprouts. My delphs grow against a rock wall, so the slugs are especially bad, but I have some in a trial garden out in the open sun, and the slugs go for those too. IMPORTANT. Don't let a single TINY bit of grass form a bridge across the copper. Slugs LOVE delphs and can climb along a thread sized bit of grass.

Broad mites (make leaves curl) - Most advice I found pointed to incredibly expensive miticides apparently available only in acre sized amounts. Then I found a university site that recommended those but ALSO insecticidal soap! Seems to work.

Earwigs - Every year when I cut back the delphs that managed to grow tall and bloom the earwigs would eat up the second growth. The solution is Sluggo-Plus. It contains wonderful spinosad and is apparently attractive to earwigs.

I'm 68 and this is the first year that I feel I have a handle on all pests that attack my delphiniums. But a new one will probably show up.... :-(


Richland, WA(Zone 7b)

My free Delph seeds are sprouting! I hope to get them in the ground this fall for a good show next year.

(Arlene) Southold, NY(Zone 7a)

Ours are, too. One slug was found and scissored with great speed.

Pretoria, South Africa

This is my first year growing delphiniums. I covered the soil around my plants with crushed egg shell because slugs tend to be a problem. So far it seems to be working. I'm holding thumbs... just love the blues of delphs.

(Mary) Anchorage, AK(Zone 4b)

I ordered seeds from Dowdswell this spring and now have a dozen or so healthy plants. I don't know if they will get big enough to bloom but have hopes for next year. I have one delph that has returned for three years and I just love it. It is over 7' tall next to a 6' fence. It gets late afternoon sun only. I am hoping the NZ plants will be as long lived.

Center, TX

Good morning, I have been trying to grow delpheniums but all I get is heads like cabbage and no flowers. I live in east Texas, hot east texas, and is it too hot for them.? Or will they come back next year with flowers? Any advise is welcome. Thanks, alda

Albany, ME(Zone 4b)

Delphiniums prefer cooler climates, although some are being bred to withstand heat. I don't know what the symptoms are of too much heat, though.

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