Growing dahlias at high rises - Singapore

Staying in high rises has one big drawback: lack of a garden. Those not with the luxury of garden can still manage to grow a few plants in pots and containers at high rises. Luckily, I have ample space in the frontyard of my south facing unit which I have reserved for my plants. Lately when we visited Cameron Highlands, we managed to get some dahlia tubers which we planted in rectangular pots (dimensions : 190 x 260 x 130 mm, 6.4 liters). We wanted to try if dahlias can grow in Singapore's tropical climate and check how they can fare in containers. There are numerous links which detail on lots and lots of tips for growing and grooming dahlias in containers. I like this one in particular. A few things which I would like to add on is,

* Use a pot of dimension at least 8-1/2 inch diameter. It would be a good idea to put one tuber per pot or container. The roots of dahlia seem to grow rapidly and they spread laterally mangling with the neighboring tubers planted in the same pot. I made a mistake of planting three tubers in a rectangular pot (dimensions : 190 x 260 x 130 mm, 6.4 liters) to save space, which I am foreseeing as a big pain. Now that my plants are getting big, I need to repot them to individual pots without hurting their roots. Do note that many individual stems might grow from a single planted tuber.

* Always plant the tubers along with a support stalk. The dahlia kids are very tender and tend to bend towards sun light. Heavy winds can bend the stems and leave the kids lying on the soil. Use a inflexible support as stalk and gently fasten the stems to the stalk at a level above the point where leaves appear from the stem. I use two cheap wooden chopsticks tied together as a stalk but note that the plant grows more than this stalk within a month.

* Use a good potting soil mix while planting the dahlia tubers. Dahlia tubers hate excess water and chances of tuber increase if the soil is more clayey( Soil has varied proportions of sand, silt and clay ). I had used cheap grade soil ($2 per pack which you get in local nurseries) which was more clayey in contents and had one tuber in a pot of two tubers. I use 'Horti's Seed and Potting Mix' mixed with 2-3 handfuls of 'Horti's Moss' per pot. You may try adding copolymer crystals along with the potting mix as mentioned in the above link, which I haven't tried yet.

* Take care not to overwater the tubers. I prefer to touch the surface of the soil with the back of my fingers to gauge the moisture level in top soil. A more proper technique is to use a hydrometer to measure the soil moisture level, which might be a bit of over-kill.

* Use some slug and snail baits to avoid the tubers getting eaten up. I use 'Horti's snail killer pellets' which is available at the local DIY shop/ Fair price Extra's gardening section. Check for fungus growth on the pellets which can occur in about 2-3 days. I try to hand pick the pellets with fungus and replace with newer ones.

* Maintain a record of your tuber growth which you can use it as reference for future. I am posting mine below. But do note that different tubers can pop out the top soil at different times and have a completely different growth rate.



My Dahlia's Growth Record



Dahlia growth after 10 days of tuber planting









Dahlia growth after 15 days of tuber planting











Dahlia growth after 19 days of tuber planting