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Downy Mildew - Can I Plant Impatiens Again?

2012 and 2013  UPDATE: Many of our customers saw Downy Mildew on their Impatiens in 2011 and 2012 – if you decide to plant them again in 2013 it will be at your own risk.

Last summer many of our Cape Cod customers were shocked when the common impatiens they’ve relied on for years seemed to just melt away. This happened in small window boxes and large estate bedding areas and was seen all over the Northeast. It struck plantings on some properties as early as late-June, and others in September. Homeowners and landscapers alike watched what was normally a sea of color turn into a forest of bare, ugly stems.

Did your impatiens look like this last year? You might have had a downy mildew attack, aka The Impatiens Plague!

The culprit was impatiens downy mildew disease. This is a fungus-like water mold with the scientific name Plasmopara obducens. The spores swim though water so this disease spreads quickly in moist or wet conditions. Spores are also carried by the wind over great distances; this explains why some people saw damage early in the summer while others didn’t lose their plants until fall. Despite having a similar name, this problem isn’t related to powdery mildew.

The question on everyone’s mind, of course, is “Can we safely plant impatiens this summer?” Unfortunately, the answer isn’t clear.

We know that spores of this disease can over-winter in the soil. We don’t know if or how the mild winter will affect this. Also unknown is if future weather conditions will promote or hinder disease problems. Most experts in the field recommend being safe and not planting common bedding impatiens (Impatiens walleriana) where there was a problem in 2011.

Fortunately, New Guinea impatiens and all types of begonias are not affected by downy mildew. Those who want to avoid a recurrence of the problem should plant these or other shade/part shade alternatives.

Is there any control of downy mildew and is it safe to replant this annual this year? If you or your customers want to plant Impatiens walleriana as usual, you can drench the soil with Actinovate  and before planting and to spray the same product on weekly, particularly the underside of the foliage. You can also use another fungicide that is labeled for downy mildew. This treatment has been shown to at least slow the disease down in warmer, drier conditions, but if the summer is cool and damp you’re likely to have your plants affected anyway. There is no “silver bullet” cure for Impatiens downy mildew. If you want to be sure to have flowers, plant begonias or other shade-lovers instead. Download a pdf sheet listing good alternatives for common impatiens from our handouts page on the website.

To read more about this disease, see this tip sheet from Ball Horticulture or in our 2013 Update.

26 comments to Downy Mildew – Can I Plant Impatiens Again?

  • Emily W.

    I lost at least 100 impatiens walleriana that I’d grown from seed last summer to downy mildew. Just wanted to say that another species of impatiens I grew also succumbed to this disease: impatiens balsamina (Touch-Me-Not).
    I am planning on growing and planting only New Guinea impatiens this year.

  • admin

    I know that it doesn’t help, but you weren’t alone! How frustrating it was for many of us to see those plants turn into bare stems.

  • John Welsh

    Sadly, downy mildew is back. I’ve lost my entire planting of both single and double impatiens to the disease. Never had it before, and originally thought the plants were suffering from lack of nourishment, even though they were planted in good, rich soil, and with a fertilizer boost when first put into the ground. From what I’ve read, replanting the area with impatiens next year or for several years later is a no-no because of the persistence of the disease. It occurs to me that it might be a good idea to get rid of the mulch too and start fresh, pathogens being what they are.

  • CLFornari

    John – so sorry that you have downy mildew on your impatiens. We agree that you shouldn’t plant regular impatiens in this location for a few years. New Guinea Impatiens don’t seem to be vulnerable to this disease and begonias are also an option for a substitute. We doubt that removing the mulch will prevent further infections but we leave that up to you.

  • john beach

    I just lost an entire 15*3 ft bed of impatients to, I assume, this disease. The strangest thing is that this disease not only killed my plants but consumed them too. Aside from a couple of splindly stalks at the far end of the bed, the entire bed of plants has vanished! I have 2 other beds on the property, but they are OK. I guess that I won’t be planting impatients in this bed any time soom. I might add that this winter was the mildest in my memory and that may have contributed to the problem.

  • CLFornari

    John,
    So sorry that you lost your Impatiens too. You’ve described just how this disease looks – it often seems as if the plants have just melted away, although sometimes a tiny forest of bare stems remains. It isn’t just Cape Cod that has had the problem…there have been outbreaks all over the country. Our advice is to plant something else such as begonias next year.

  • Dee

    I just pulled out 12 flats of impatiens due to this disease. It literally turns my stomach to see my mounds and mounds of color turn to plain stems. No other flower presents as beautifully as these. Is it true that I can’t ever have these again? Or will there be some “cure” to this disease in the future?

  • CLFornari

    Dee -
    We feel the same way! There is nothing like Impatiens walleriana for easy, inexpensive, season long color! Unfortunately it looks like you won’t be able to plant these for several years to come. What we know is that in areas of Europe that have had this disease they weren’t able to plant them again for many years. It seems, however, that the spores are killed if the winter temperatures drop below 5 degrees for any length of time, so if we have a very cold winter it’s possible that it might go away. No one knows for sure, however. The new Sunpatiens are resistant (I am growing them myself this year with no problem, even though I had the disease on my property last year.) as are New Guinea Impatiens, all begonias and coleus.

  • fran

    I purchased 12 full flats of impatiens, the same as every prior year. Every plant became spindly and lost their leaves. I thought it was due to a very hot May and June. I am glad that it is not just my garden. I will plant begonias for the next few years. This mess cost me over 250.00!

  • CLFornari

    Fran,
    You aren’t alone – all around the Cape we see a forest of Impatiens stems! I was recently at Willowbend where they forbid anyone to plant Impatiens this year since they had the downy mildew problem last year. They used pink wax begonias instead and I have to say that it was beautiful. We’re thankful that there are so many great alternatives.

  • I am so glad to have come across your website. I had this problem last year, but I had no idea what it was. I just thought it was a bad batch of plants.
    So I planted impatience again this year. Sadly they are all destroyed. At least I know now what it is, and I will not plant them again next year to try to stop the spread of the spores.

    filly brown

  • Browns Fan

    Our whole neighborhood has this problem this year…first time in Cleveland area…

  • CLFornari

    Our sympathies to all who have this disease. We’re recommending begonias, New Guinea Impatiens and Sunpatiens to all our customers for at least the next few years. We’ll keep everyone posted with updates.

  • Last week I gave in-dug up 300 plants-have never seen this before- have been planting impatiens for over 40 yr– 6 hanging plants are next to go! thank you for all the suggestions!!

  • CLFornari

    I know, Fran – it’s heartbreaking that we may not be able to plant this normally foolproof annual for many more years. Fortunately the New Guinea Impatiens just keep getting better and better, and the Begonia selection continues to grow!

  • renita jackson

    Can I Still use the soil my Impatiens were planted in when they got downy mildew. I will plant begonias

  • CLFornari

    Renita,
    You can use the same soil since Begonias aren’t susceptible to this downy mildew. If you’re planting in a container, however, you might want to “refresh” the soil by adding a few scoops of compost and a small handful of an organic fertilizer. Happy Spring!

  • Dirty Gertie's Gardening

    I do gardening for a small handfull of clients and a few of them use impatiens in large drifts. For the rest of my clients I can substitute New Guinea or Begonias in their “impatiens” areas. However for my clients that use a tons of them there is a huge difference in cost between a 6 pack of regular impatiens and the larger pot that New Guineas are sold in. For some of my clients the difference in price is too much.

    So I have a few questions:

    Why aren’t New Guineas sold smaller in a 6 pack?

    Is there something else that is less expensive that will work in shade? (I like a Coleus but most of my clients want “flowers”)

    Are they hard at work trying to insert a gene from lets say a New Guinea impatiens that makes them resistant to the mold into a Walleriana? A spray would be ok but again, for large drift plantings at some of the estates I work at or for commercial drift plantings spraying isn’t a very good option.

    Thanks Country Gardens I’ve had a partnership with you for many years… you’re the best!

  • CLFornari

    All great questions, “Dirty Gertie.”
    New Guineas are sometimes sold in six packs but they aren’t the same plants as those sold in pots. Usually when an annual is only sold in pots it’s because it’s propagated by cuttings only. Some plants are either easier to grow from cuttings or only possible to grow from cuttings. Also, when a plant is propagated by cuttings you know that it’s going to always be the same plant…seed grown plants can vary. (If you’ve ever grown Cosmos you’ve probably had the experience of some blooming well and others just making a tower of green foliage with few flowers – this is because they are grown from seed and can vary greatly in growth and habit, even when you buy a named variety.)

    The New Guineas that we will have in six packs will still be more expensive than the Impatiens or Begonias in six packs. Also, know that the New Guineas sold in six packs are seed propagated and not the same plant as those sold in pots. They tend to not be as wide or have as many flowers. Be sure that you plant all New Guineas with a combination of time-release fertilizer and an organic fertilizer for feeding all summer – we often use a 50-50 combination of Osmocote and Flower-tone.

    Begonias are your best alternative. The “Whopper” begonias get large and so cover a great deal of space. Last year in Willowbend the landscapers used all greenleaf wax begonias with either pink, white or red flowers and the result was stunning – again, they were well fertilized.

    Yes, the breeders such as Ball Horticultural are working like crazy to develop a seed grown Impatiens walleriana that is resistant to downy mildew. All of America is cheering them on!

    Agreed that although spraying weekly can slow this disease down, the cost of doing so in both time and product makes the plantings much more expensive…for that same money you could get all New Guineas or all Whopper Begonias. Not only that but spray can only hold off the infection for so long…in cool and damp conditions the plants are likely to get it anyway.

    Thanks for being a regular customer…we’re happy when you’re happy.

  • Sherry

    I am the gardener for a major university in Wisconsin. I have planted a large bed with Impatiens for many years. Last year I watched my beautiful bed crash and many blaming thoughts went thru my head. I finally figured it was some kind of disease and planned to plant a different shade flower this year. Now I know for certain what the problem was–thanks to Country Garden!

  • CLFornari

    Hi, Sherry! Glad we could help. This disease was seen nationwide last year. Horrible, but there are many alternatives and while the plant breeders come up with something that’s resistant it gives us a chance to try new things.

  • Dirty Gertie's Gardening

    Thanks so much for the information CL! I’ve been planning what to use for my clients that use drifts of impatiens and I’m going to take your advice and go with the Begonias. In a few individual spots (not large drift plantings) I’m going to try and some Coleus and Lobelia. I used lobelia in an under tree planting at an office in Osterville last year and although I was told it would not bloom all season, it did. It was in fairly deep shade with a irrigation system and it looked great.

    We are going to miss our impatiens and I hope Ball Horticultural is successful in producing downy mildew resistant Impatiens. In the meantime we’ll be stepping out of the box to try new things. See you soon Country Gardens!

  • Kathy

    I looked at all of the impatience that I planted and they are dying and at first I thought, too much rain that we have had here in Notheast Ohio, but this is the second year in a row that this has happened; I plant impatience because they are beautiful and we have a lot of shade. I thought I would take a look online and found this website and found that it must be the downy mildew, I have never had this problem, my New Guinea impaients look great. I think I will be planting them next year instead of the impatience. Happy I found this website!

  • CLFornari

    Kathy,
    I’m glad that this was helpful. If you ever come out to Cape Cod be sure to stop into our garden center and say hello.

  • Gary Bumgarner

    I Googled “New Guinea Impatiens melting” and found your website. My Bavarian Chalet is surrounded by 175 feet of flower boxes and I have planted the shady sides with N. G. Impatiens, common impatiens, and wax begonias. They all melted away and died except for those that get a decent dose of morning sun, where they thrive beautifully. What other colorful plantings can I make in Eastern Washington that this disease won’t affect?

  • CLFornari

    Gary,
    Your begonias and New Guinea impatiens shouldn’t have melted if you have Impatiens downy mildew – it only affects the common impatiens. If the other plants also died I’d suspect over watering…all three of these annuals will succumb to crown rot if the surface of the soil is kept constantly wet, especially if you have cool nights. If the beds are being watered frequently the areas in morning sun might be drying off better so you’d see successful plantings there. If you think this is the case, water deeply less often so that the surface of the soil is allowed to dry in between soakings but the roots are kept moist.

    If your plantings are in deep shade all varieties of impatiens won’t flower well. Even the wax begonias flower better when they get at least three hours of direct sun. For deep shade you’ll be better off planting perennials such as hosta and ferns and using colorful pots, a colorful bench, brightly painted posts topped with bird houses or other man-made objects to brighten the area.

    I hope this helps!

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