How to Grow Delphiniums: The Complete Delphinium Flower Guide

H, Sandra, Larkspur (Delphinium grandiflorum) is naturalized in much of Texas. However, they are fall-seeded annuals and they complete their flowering in late spring. Then you replace with hot-season annuals, such as periwinkles, celosias, or purslanes. As you said, they do better in places with fairly moist summers versus hot weather but there are heat-tolerant varieties in Texas and perhaps you have one! Just put lots of composted manure in their bed and make sure the soil stays well-drained as delphiniums hate wet soil. Don't let the soil get too hot. Stake them as they grow tall!

Very informative info, I bought one 2 feet tall from a greenhouse 3 weeks ago and it is thriving. Now almost 3 feet tall with 2 flowing spires and a third growing. I'm in Denver and it's very hot now. I keep it moist with the ground soil damp. It seems to be working...

Will Delphiniums winter over in Lake Tahoe in the Sierra Nevada's ?? We can have up to 20 feet of snow ... Many thanks

Many varieties of delphiniums are winter-hardy up through Alaska and Canada. Mulch well with several inches of hay; some folks use pine branches to provide a loose protection from severe frosts.

I’ve been growing delphiniums in New York City (on a very sunny terrace) for many years. I grow the delphiniums in fairly large clay or plastic pots--24 in to 30 in. diameter, using a combination of top soil, sand and compost. (I use soil and peat-moss with most plants, but peat-moss is acidic and delphiniums don’t like acid soil.) I buy the top-soil from a local garden center,and I find that it serves well for a great many years. I just add a little compost annually. In the past, my delphiniums always bloomed, but it took me a while to figure how to help them to make it through the winter. (We usually get snow--sometimes a lot of snow--2 or 3 times. And the temperature goes below freezing quite often.) By trial and error I learned: 1) to put sand around (but not on) the base of the delphiniums. I buy it from a hardware store) Otherwise, the delphinium crown is likely to rot. I also use some sand in Spring and Summer to protect them from rotting after heavy rains. THIS IS CRUCIAL (I put sand around columbine (aquilegia) for the same reason.) 2) After the first bloom, I cut them back, and they always re-bloom. 3) during spring and summer I give them low-nitrogen liquid fertilizer every 3 weeks. (the same fertilizer that works well for my roses) 4 When the ground freezes, I replenish the sand (as needed) and then cover them with evergreen branches from our Christmas tree. (I get extra branches from people on the street who sell Christmas trees--they charge very little. I have found that other types of mulch keeps them too damp. The evergreen branches let air circulate. I remove evergreen branches only when I’m quite sure that there will not be another hard frost. (here that is mid-March to mid April) After removing branches, I add compost, and as the plants begin to grow I begin to feed with the low-nitrogen fertilizer. None of this is hard--and in my experience, it’s fool-proof I’ve had 5-9 foot delphiniums survive 4 or 5 years, blooming twice each year.

I live in northern BC , Canada. I have never mulched and my Delphiniums keep on coming back, bigger and more beautiful each year. The 3-4 ft of snow cover seems to insulate them very well.

I planted dark purple Delphiniums (don't remember exact name) in my flower bed. The new flowers are coming out a very pale purple. What do I need to do to get the flowers back to the deep purple?

There are a few theories as to why a delphinium might change color. If this is not the first season, it could be that the new flowers were from seeds of the parent plant, and if that parent was a hybrid, the seeds may exhibit traits not displayed in the parent, such as lighter color. If this is indeed the same plant, but the flower color has changed over one season, there is one theory that a change in weather, such as cold damage to the roots, or high temperatures, can cause the flowers to change color. Another theory is that the soil pH can affect color. However, this normally would not explain a color change over one season. Delphiniums usually prefer a neutral to slightly alkaline soil. We'd recommend checking your soil pH, and adding lime to an acidic soil to see if that helps. (Also, a delphinium flower will change color as it ages; but this wouldn't explain your flowers not having started out dark purple.) Hope this helps!

I recently bought two flowering delphinium plants and planted one in a pot with potting soil that the garden store uses. It gets full southeastern sun. I watered well. Within two days, the leaves are withering and the flowers are drooping. I watered well again, no change. What could be the cause?

The plant may show transplant shock and will recover. Delphiniums like cool weather, so if you have had the plant in full hot sun it would be wise to move it to a spot with afternoon shade until it recovers.