PLEASE - Do not plant your tubers!
This is the time for all the dahlia tubers you have ordered to arrive on your doorstep. When is the right time to plant dahlia tubers in your garden? In most cases it is in late spring. The days must be warmer and all the possibility for frost must be over. For me in the middle of the country that is the week after the 24 September long weekend. National Braai Day is infamous for being dreadfully cold here in the Northern Cape and often that is our last frost date. Dahlias originally came from Mexico and they love the summer heat and I think that is why they are so happy growing in my field, but if you want them to fail, plant them too early.
Temperature is not the only reason why I do not want you to plant your tubers, there is a far more important reason. The only problem is nobody wants to talk about this important reason. It is like the elephant in the room, everybody knows it is there, but no one wants to acknowledge it. So here it is... by doing this I am opening a hornets nest, but I think it is very important for every person who grows dahlias to know about this.
Elephant in the room
The reason is CROWN GALL."kroongal" in Afrikaans.
Crown gall is caused by a bacterial plant pathogen, Agrobacterium tumefaciens. No need to worry about all the science around gall, what you need to worry about is that you do not introduce gall into your garden. On my farm we call gall the AIDS, so everybody can understand the seriousness of this disease. There is no cure for gall (I know there is one for Aids), but this is how I explain it. Gall is highly contagious. If you plant a plant with gall in your garden, the bacteria will spread and infect everything that is susceptible to gall. And then one fine day you will realize your whole garden is sick. So what does this have to do with dahlias you may ask.
Dahlias are highly susceptible to crown gall and a lot of people have gall in their tuber stock, knowingly or unknowingly. There is also the problem with imported dahlia tuber clumps. There is a high probability that imported tubers from Holland may have gall. Out of 60 new varieties I imported 6 of them had gall. The whole gall epidemic in America started with imported tubers which were diseased and then it started to spread. So what now? Well the only way to ensure that you do not spread the disease into your garden is to start all your new dahlia varieties in pots. This you can do now when your tubers start to arrive. Plant the tuber in a pot with good potting soil. Keep the soil moist, not wet and place the pot in a warm place (I use my warmest sunniest room), but you must remember to keep it out of direct sunlight. Let the tubers start to sprout and grow roots and then take them out of their pots, clean the crown part of the tuber and carefully inspect if there is any suspicious growth. In this picture you will see how it looks, as if millions of eyes want to sprout, well this is gall. And the only way to make sure your tubers are clean is to give them a chance to sprout and to check them visually.
Crown Gall on one of my imported tubers
Gall looks like a million growing points on the crown
Ok, what happens if one of your tubers has gall? Sorry to be the one who has to tell you, but you will have to throw that tuber/clump away, and I do not mean onto the compost heap, NO into a plastic bag soil and all, and then into the garbage or even better, burn it. So what do you do if you start digging your tubers from last season to divide them and find gall in last year's plants? Dig up that plant and remove all the soil where it was previously planted. Discard the plant and the soil.
So to be clear, gall is already in South African gardens. I have 3 000 plants and 8 of them had gall. I took these plants and their soil out of my field and took it off my property and then burned it. So I really try to keep my farm as gall free as possible, but it is no guarantee. This is also the reason that I will only be sending your orders after 15 September 2024. About a month before I start shipping my tubers, I begin to heat them up, then they can start showing their eyes. It is then also possible for me to check that the tubers I am sending to you do not show signs of gall. It is still not full proof, but it is the only way to do it.
This is the bag with growing medium and a healthy tuber I will send to you
So when my tuber arrives at your house, I want you to leave it in the bag and growing medium that I sent it in. Keep it in a warm place for a week or 2 to check on them further. If anything looks fishy please let me know.
A healthy tuber with a eye growing into the first stem
So after this heavy topic I hope you are still excited about the upcoming dahlia season. I am so excited I can not wait. I have about 120 new varieties I am growing to share with you next year. So exciting stuff to look forward to.
She who loves dahlias
Mareli