Frequently Asked Questions

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What is the difference between the different types of delphiniums?
Please see this article in our Terry's Says section.

Do you have red delphiniums?
We do not produce seed for red delphiniums. This is a decision we made many years ago for a number of reasons: Red delphiniums were first bred in the 1950s but have not yet to date produced substantial, long lived plants and we do not like to sell weak plants. They are extremely difficult to produce economically from seed and currently only available from tissue culture and cuttings sold by some vendors. The breeding work involved to produce a strong red seed line would be enormous and we have other more promising breeding work in development. We really don't want to do it. We do have very deep mulberry pinks such as Pink Punch. This is as close to red as we are able to go right now.


Will second generation seeds from your line breed true?
Unfortunately, delphiniums do not grow true from seed. We can grow consistent seedlines giving know results only by crossing the right parent plants. This is part of what makes our hand crossed seedlines so expensive. There has been many years of research into establishing the right parents to cross to get the seedlines we sell. And the hand crossing of the pollen from the male parent to the female parent is very labour intensive. You can save the seed and see what you get - they will still be good plants, just not the same as their parent.

How do I save my own seed from delphiniums?
Wait until the seed pods begin to turn brown then remove them and place them in a paper bag and hang them up somewhere dry and below 20Deg C. (75Deg F or so). They will dry in a week or two and the seed will fall out of the seed pods into the paper bag. They are then ready to sow.

Will the seed you send me be viable?
We sell delphinium seed according to viability, not age. All are above 70% when packed. Most germinate above 80% and some like Sweethearts, Purple Passion, Green Twist, Pagan Purples and Dusky Maidens are over 90%. Where germination may be less than 75% we pack extra seeds.Even so, all seed in stock is either this or last season's seed.

Why didn't the seed you sent me germinate?
All our seed is germination tested to above 70% (in most cases over 85%) before we allow it to leave our nursery so there should not have been a problem with the seed. However, sometimes things do go wrong; the seed may suffer in transit, be attacked by fungi, drowned, dried out - the list is long. However, we like our customers to have a pleasant experience and therefore have a policy of replacing properly sown seed that does not perform. All we ask is that you check your sowing methods against our recommendations and get back to us with the results of the replacement seed.

When should I sow the seed?
When to sow is a difficult question to answer. Some folk like to sow in Autumn (Fall) to give them a small plant to overwinter either in the garden or in a cold frame. Some pot up the seedlings into small pots and keep inside over winter. For me, I would sow in Autumn, raise plants in small pots then place them in a greenhouse, conservatory or other light, cool place overwinter. If left outdoors over winter I recommend leaving them in pots and covering them with plenty of mulch, twigs etc to protect from the worst frosts. Mid Winter sowing is a good option too. The trade off is that although it is less bother you will not get flowers until late summer or so whereas a fall sowing will give you blooms by mid summer - otherwise no difference. Many commercial growers sow in late summer and keep them in a cool greenhouse over the winter. The young plants will have time to grow sufficiently to be able to be planted in small pots. They will be ok in the frost outside if, when they die down in the winter they are covered with a layer of loose mulch (eg straw or leaves and twigs). For more general growing information see: and in particular here: Need to know more about growing from seed? Check out this excellent tutorial Gardening 101 at the Garden Helper site.

My seeds have germinated - what do I do now?
First of all, well done getting them germinated. I appreciate this is a new adventure for you and as such can be quite frustrating. We've been growing plants for a lifetime and probably take many things for granted so we've had a look around for some good instructions and explanations about the growing process and come up with a really good website that should be helpful. If you follow this link you will come to page that discusses how to sow and grow plants from seeds. Follow the page down until you see the heading "The critical seedling stage" and this will give you good guidance about what to do now. The whole page is full of useful information not only about what to do, but why. Understanding the "why" is the key to continued success so I would recommend careful reading of the whole page. You will find it useful for growing all types of plants. With regard to your delphinium seedlings, once you have re-potted them into small pots and the roots begin to emerge from the bottom of the pot, they will be ready to plant. This should take 4 to six weeks. When you do plant in the garden choose a coolish place and mulch them well to keep the roots cool and moist.

Why can't I buy seed for (insert delphinium name here)?
We produce many seedlines and cloned plants. If the delphinium you are searching for is not one of the ones we have bred, then you can't buy it from us. If the delphinium you are searching for is one we have bred then you need to find out whether it is a seedline or a cloned plant. If it is a seedline and you can't find it on this year's seedlist then sorry, but it is not available. There are many reasons for this mostly to do with breeding decisions and time. If the delphinium you are searching for is a cloned plant then it will never be available as a seedline. We may eventually produce a seedline that is simlar but it will be sold under a different name. Delphiniums do not grow true from seed (see above). Cloned plants are grown from cuttings from our best plants and can only be sold as plants. We cannot sell plants overseas, only within New Zealand.


How do I treat Delphiniums for Broad Mite, Bacterial Blackspot, Sclerotinia rolfsii (also known as Delphiniums Blight) or leaf-tier?
Please see this page

How do I get rid of Sclerotinia Rolfsii?
Sclerotinia Rolfsii is a real nasty and very difficult to completely eradicate from the garden. The best control we have come across is to use Jeyes Fluid (which you may be able to source) as a soil fumigant. This works well where infection is limited to small areas. Solarisation in climates where you have plenty of hot sun can work too. This is a case of covering the ground with black polythene for several weeks over the hottest part of the summer. Don't expect to eradicate it though. The very best cure of all is to not grow plants that are susceptible. I'm not sure how long S rolfsii will remain viable in the soil without a host but if anyone finds out, please let me know.

Can you send plants overseas?
Sorry, no. We do not export any plants or cuttings or tissue culture material to any countries because of the extreme difficulty and cost in transporting and growing them. It is just not economic at all.

Why have my plants died down after flowering?
This is a winter dormancy thing. Just check that the crowns are still solid and if you don't have snow cover, put a few slug pellets on each one on the first of each winter month. In Spring you will have new shoots charging away. Give them some compost or fertiliser in two or three weeks after growth starts.

Why didn't my plants come back to flower a second or third year?
There are two possible reasons: 1. Your climate is too warm - many people need to treat delphiniums as annuals if their climate is too hot or humid. 2. The snails/slugs got them. Snails and slugs LOVE delphiniums and will eat the tender new shoots before they reach the surface in the spring - that is, while they are still underground and before you can even see the shoots. You need to put slug bait down regularly over winter if you don't have snow cover, or as soon as the snow melts if you do. Put it down on the first of the month every winter month until the shoots reach the surface.

How close or far should I plant delphiniums?
Don’t crowd the poor things. Plant in small groups - but leave a good metre and a half between groups. Why not surround the groups with roses? They will give the delphiniums support and you won’t have to stake them. They’ll look great together too. More space means shorter, sturdier plants. I can’t emphasise this too much. Most of our varieties simply do not need staking if grown correctly.

How high will these delphiniums grow?
We don’t give specific heights, only comparative ones as it varies greatly according to how you grow them. If you give them plenty of space, they will grow strong but not as tall as if you crowd them. If you give them perfect conditions they will grow taller than if they are kept short of food and water. Generally, whites and pinks tend to be shorter than blues and purples. However, we have collected some lines that tend to be shorter or taller and put them in BSH5006, mix of shortest, and BTA5001 mix of tallest.

Why are some plants priced at nearly twice the price of others?
The difference between the price of the plants in 9cm and 14cm pots is not their size but their provenance. The more expensive plants are grown from cuttings the previous year, potted into 9cm pots and then finally potted into 14cm pots either in the autumn (May) or early spring (July). Named, cutting grown varietiesv such as Sarita and James, are the very best plants selected from thousands of seedlings. These plants are then bulked up through cuttings over several years. They are true to colour and form in every respect. That is why they are more expensive. Plants from the seed grown range such as Sweethearts and Pink Blush, in 9cm pots were grown from seed sown in April or May. They are reasonably true to colour and form but no two seedlings will be the same. They are much cheaper to produce, hence the lower price.


How do I treat flowers to prevent petal drop?
We discuss this here: Post Harvest

Where can i get silver nitrate?
I no longer buy silver nitrate. Have you tried a chemist (pharmacist)?  Failing that your local camera club may well have someone who still uses it for developing black and white film.

Is there an alternative to STS?
No, the only way to protect delphinium flowers is treatment with STS (commercially known as Crysal AVB).

Sarita and James, as with all named, cutting grown varieties,  are the very best plants selected from thousands of seedlings. These plants are then bulked up through cuttings over several years. They are true to colour and form in every respect. That is why they are more expensive.

Sweethearts and Pink Blush, in 9cm pots were grown from seed sown in April or May. They are reasonably true to colour and form but no two seedlings will be the same. They are much cheaper to produce, hence the lower price

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Dowdeswell's Delphiniums - Wanganui, New Zealand