It’s SPRING…which means PLANTING TIME!!!! The general rule of thumb (here in Victoria, Australia) is to plant tubers around Melbourne Cup day, the first week in November. This is generally due to many parts of the state still experiencing late frosts into October, and ensuring the temperatures are consistently warming up the soil. Wet Spring weather can also be a nightmare…..too much rain risks soggy soil and rotting tubers (which can be aided by planting in raised beds, having well prepared and great raining soil, covering beds with a tarp in long or heavy downpours etc).
We have been very lucky to have had lovely warm temperatures for this part of Victoria throughout October, and very little rain, so conditions have been optimal for planting the first of our waking tubers. The first batch of Dahlia tubers waking up were planted 3 weeks ago. At the time of planting, each had at least one visible eye starting to sprout. Soils were moist but not wet and we only had several nights down to 1 or zero degrees. After 3 weeks, almost all of the planted tubers are already poking up through the soil (the surface of which looks SUPER dry in the photos, but just below surface the soil is damp).
Many people ask how long tubers take to start budding their eyes, and how long for shoots to surface and produce leaves. Dahlia tubers each have their own personality…..some wake up early and are raring to go, others will remain dormant for weeks and weeks. The average rule of thumb is up to a 6-8 period from first to last tuber waking and starting to grow. While climate, temperature, storage medium and tuber health will have a significant impact, some varieties simply take longer than others. The same rule applies when waiting for growth to make its way to the surface. Patience in important…..too much disturbance of newly rowing tuber roots can actually delay or slow down the growth speed, so if you feel the need to check on the tuber (if you are worried it might be too wet or rotting etc), gently dig down from the side but try not to disturb the roots or the tuber itself. Avoid digging from above when you might risk breaking off the new delicate shoot (if you do break it off there is no need for alarm….the tuber will send out several more in its place). Each week more are waking and joining their pals in the garden beds.
WATERING: The other common question at this stage of the season is around watering and fertilising. Tubers need moisture to ‘wake-up’ and commence growth. Damp moisture but definitely not wet and soggy. Many people find that commencing in healthy, damp soil does not require any additional watering until the plant is approximately 15cm tall, but like everything in the garden, this will vary considerably based on a wide range of factors such as soil health & drainage and weather (heat/rain etc). My watering regime varies every season! So get to know your soil, and get to know your plants…..over time watering becomes an intuitive and flexible process rather than a systematic ‘every 2-3 days’ process.
FERTILISING: There are MANY brands and varieties of fertiliser available. Dahlias are heavy feeders, which is how we get lush beautiful blooms, but this doesn’t mean it needs to be complicated. Each grower develops their preferred range and method of fertilising their Dahlias. Whilst regimes differ slightly between growers and regions, following a simple guideline will help maximise the quality and quantity of beautiful blooms. Just like watering, fertilising needs are also impacted by soil quality. If you are new to growing and fertilising Dahlias, check out your local or state Dahlia Society or onlines growers groups for a range of helpful information. Start with a simple, manageable routine and find out what works best for you in your region.
The basic guide for dahlias is adding a handful of pellet fertiliser around the time of planting (approx 3 weeks prior to planting when doing the final preparations of my soil, I rake in blood & bone and dynamic lifter. Soils have been well prepared prior with well rotted manure, mulch/compost, handfuls of used coffee grinds and an incorporated winter cover crop). I also like to add a good handful of BioChar throughout each of my raised beds. When planting tubers, I add nothing else. If the soil is on the drier side, I moisten it at the time of planting. Fertilising then generally begins when the plant is around 20cm tall. When growing Dahlias, fertilising is generally split into two regimes…..
EARLY STAGE FERTILISING: Commence with a balanced fertiliser (usually liquid) to provide the newly growing plants medium-high levels of nitrogen to promote foliar growth (leaves). Growers each have their own frequency…a popular saying is ‘weakly weekly’…..but if you are like me and don’t have as much time as you would like…I apply liquid fertiliser 2-3 weekly via a watering can or hose attachment tot the base of the plant (at approx 3/4 of the recommended dosage. Every alternate rotation I also add Seasol to the mix (a soil improver, not a fertiliser).
FLOWERING STAGE FERTILISING: When the plant starts to produce buds, you want to reduce the level of nitrogen being applied otherwise the plant will continue to produce lush green foliage, at the expense of blooms. Switch to a fertiliser higher in potassium and nitrogen. Most fertilisers for flowering plants will be fine. Liquid potash is my go-to from this stage onwards. I apply this 2 weekly, and every second rotation I also add Seasol.
Avoid fertilising during the heat of the day, to reduce stress on the plants. Fertilise early in the morning, or late in the evening during particularly hot days. Continue fertilising throughout the flowering season. Start reducing watering and fertilising as the weather starts to cool down. The timing of this will depend on your region and the conditions at the time, here in Victoria this is usually towards the end of March. Applying a low nitrogen fertiliser in early Autumn as the plants are starting to die down will assist the plant in putting its energy into its tubers ready for winter.
It is easy to become overwhelmed by the varying advice and recommendations about fertilising….frequency, which products are best etc…..so keep it simple. Over time you will find the best regime that works for you. Just remember, there is no perfect scenario and what you do one season will likely be different next season, so enjoy the process and if there is a part of your system that doesn’t work as you had planned, use it as a learning opportunity to enhance your system next season.
Stay tuned for more handy guides and updates throughout the season. Most importantly….HAPPY GROWING EVERYONE!
