The Midsummer Malaise

Have you looked at your dahlia plants this summer and thought: What is going on with my dahlia? It looks awful!

You may be suffering from what I call “The Midsummer Malaise” (TMM). TMM isn’t an official disease or anything like that. But it’s a common issue I see on Dahlias at least once a summer, especially if you live in a hot climate.

Usually it looks a little something like this. Brown crunchy or soggy (if it’s been wet) leaves or perhaps yellow leaves if you catch it early. These are signs of stress. Ideally dahlias love more moderate cooler temps- 60-70’s. Well most places don’t get those until Fall. But in order to have dahlias in the fall, you have to grow them through the summer. So you have to get them through the heat.

So what do you do about it?

1. Clean up the plant. Remove any brown, yellow, crunchy dead leaves— anything that’s not green and luscious.

They should look like the picture below. Some growers actually pre-emptively remove all the foliage on the lower 18” of the plant. But I find that’s a lot of extra labor for 2200 plants. So I remove it where needed.

2. Inspect the plants for any sign of disease- especially powdery mildew. PM looks like a white dusting on your leaves- when it starts, it can occur just in small spots on the leaves. We’ll talk more about how to deal with PM another time. For now just notice if the plants don’t look “normal.” And by normal I mean, they should be solid green - dahlias don’t have any variegation in the leaves. It’s very slight in the photos below but those lighter greenish yellow patches are a tell-tale sign.

If you see sings of yellow mottling, then you are going to want to investigate further. That could be a sign of disease or nutrient deficiency. I tend to treat for nutrient deficiency before assuming disease unless I see any other tell-tale signs of disease.

3. It’s time for a little TLC. Dahlias are pretty hungry and need to be fed regularly to perform well. So it’s time to fertilize.

The type of fertilizer is going to depend on the stage of growth. If your plant is less than about 6 weeks old then a fertilizer that includes a bit of nitrogen is good. Dahlias don’t need loads of nitrogen. Nitrogen promotes green growth. Generally you are looking for a fertilizer that is higher in phosphorus and potassium. This is a good time to know what nutrients your soil contains (hence the reason you always hear gardeners talk about taking a soil test).

***But I know most of us didn’t stop and soil test this spring. (Don’t feel bad, I didn’t test for several years when I started gardening). You can test this fall and you’ll be ready for next year!***

So if you don’t know what nutrients your soil is low in, you do fly a little blind. But since we know that dahlias like phosphorus and potassium, we’ll look for that. Fertilizers that are made for tomatoes or roses are also good for Dahlias. I encourage you to seek out an organic fertilizer. Also I prefer liquid feeds at this point. I use a powdered/granular fertilizer when planting but prefer liquid during the growing process. I just find it easier to apply. (Brands differ from place to place and that’s why I feel it’s more important to tell you what to look for in the fertilizer than an actual name brand.)

Feed your dahlias (according to the instructions on your fertilizer) about every other week from now until about a month before your first frost date.

4. Lastly, make sure your dahlias are getting plenty of water. You can’t do anything about high heat but you can control the moisture. I try not to let my soil completely dry out. You do want to make sure you have good drainage though. Dahlia tubers don’t like sitting in mucky wet soil.

The Midsummer Malaise is bound to get you at some point and some years it is more extreme than others. But it doesn’t have to spell a death sentence for your plants. It just means it’s time for a little garden therapy for you and TLC for your plants!

Getting the most out of your Dahlias

The weather has finally turned to Fall here in the South. Let’s talk about the queens of Fall— Dahlias!

Miss Amara in the greenhouse

Vase Life
If you’ve ever cut a dahlia and put it in a vase, you know they can be short lived beauties. However they have such a jaw dropping beauty that I don’t mind their lesson in appreciating all beautiful things no matter how fleeting. If you are growing your own, cut early in the morning for best results, late evening if you aren’t an early bird. The sugars in the plant are at their highest in the morning. Never cut in the heat of the day. Place in a cool container of water (make sure your vase is squeaky clean— think “would I drink out of this?”) Then add a bit of flower food. You can buy flower food online from places like Amazon or floral supply sites. Chrysal and Floralife are two popular brands. It comes in liquid or powder form— both work well. You are looking for the one that says “flower food”, not quick dip or holding solution. Maybe that sounds obvious but there are a lot of choices out there.

**After writing this blog post, I got a few questions from other growers and wanted to note that this blog was written for the home grower. Commercial growers have other tools (flower coolers, etc. ) available to them for conditioning. Conditioning dahlias for sale to a wholesaler or florists as a commercial flower grower would be a whole other blog post.

When receiving a bouquet of dahlias, you follow the same procedure. Recut about a 1/2” off the bottom of the stem, place in clean cool water in a clean vase. Dirty vases and dirty water are the enemy of making your flowers last. Change the water every day if you can, at least every other day. Also, recut the stems and add more flower food each time. If your bouquet contains a packet of flower food— you can split it in half if your vase isn’t too big.

Growing Dahlias
A few tips for this time of year if you are growing dahlias. It’s time to stop fertilizing them. You don’t want to generate a lot of new growth. We are mid way through September and from now on out, the plants won’t produce too many new buds. The already formed buds will develop and bloom. You’ll start to see the blooms taper off by mid October. The plant will also be putting a lot of energy into developing tubers. This time of year is when you really want to watch the amount of rain we get. Extreme heavy rains can cause tuber rot and also produce softer tubers that don’t store well. We’ll have a frost by early November most years but as long as your dahlias have been in the ground and growing for at least 120 days, you can dig the tubers before frost. The tubers will be fully formed. So if you don’t relish digging tubers in the cold, you can go for it by late October usually. I’ll post a blog in a few weeks about digging, dividing, and storing tubers.

***If you are a commercial grower, you can do one last fertilization about 6 weeks before your last frost which would be about now in South Carolina. The intense production required by commercially grown plants requires more nutrients than the average backyard dahlia plant.

After the vase
There are a few options for your blooms after you’ve enjoyed them in the vase. You can hang them upside down to dry— the fuller the bloom and brighter the color, the better it dries. Dahlia petals are edible (although I don’t think they taste that great!) But you could style your food for your latest Instagram post with dahlia petal sprinkles. You can also pull the petals off the bloom and make art. I like to deconstruct the flowers and make mandalas, flower quilts or abstract designs. It’s very relaxing!

I hope this helps you to get the most out of your dahlias. If you haven’t gotten a dahlia bouquet from us this year, it’s the perfect time for it. The dahlias will be at their absolute best in the next few weeks. Check out our website for more information.