Deluxe dahlias

Dahlias Blue Wish and Titoki PointI planted 23 different varieties of dahlias yesterday – mostly pinks, purples, magentas and reds, with a couple of white and peach varieties thrown in for good measure. A week ago, and not too far from here (about two turns left and one turn right), I journeyed the neighbourhood and spied two fully grown dahlia plants already flowering their socks off. If they could thrive not five minutes away from my own doorstep, it was high time I planted my own.

Dahlias are one of the most prolific flowering perennials and come in myriad shapes and sizes, from neat-as-a-pin pompoms to spidery cactus types and paeony and water lily lookalikes. The flowers range in size from tiny-tot heads less than 50mm to giants with a diameter of over 250mm.

Condition your soil

Plant your dahlia tubers once all risk of frosts has passed. September is a good time to plant tubers, but leave it until October if you often experience late frosts.

Choose a sunny spot with free-draining soil. Dig over the soil and incorporate compost (ideally you should do this a few weeks before planting). Avoid using fresh manure or compost that hasn’t quite broken down as these can cause excessive soft growth which is susceptible to mildews and stem rot.

Dahlias are heavy feeders, so incorporate a balanced fertiliser such as Nitrophoska Blue at planting time, or apply a good dressing of blood and bone. Apply this 10-14 days before planting your tubers.

Planting out

Plant the tubers so that their necks are 5-6cm below the soil. If tubers have already sprouted, position them so the base of this growth is just below soil level. Scatter slug and snail bait around the plants too as those pesky molluscs love to munch on the sprouting tips.

Tall dahlias will need staking, or there may be tears and tantrums if you find all your flowering stems flattened after a night of rain and high wind (try to avoid windy spots though). Insert the stakes at planting time to avoid root damage later.

Water when necessary, but don’t overdo it. Too much water can cause root rot.

When your plants reach about 30cm high, nip out the centre to encourage them to branch out and provide more flowering stems. Tie the plants to your stakes too as they grow, starting when they’re just a little over 30cm.

Photos above, from left: ‘Blue Wish’ from GardenPost; ‘Titoki Point, bred by Dr Keith Hammett and available from NZ Bulbs.


  1. Flowers are so inspirational – it’s cuuoris to see what flowers you get to enjoy at Christmas-time down under! I recently posted about flowers and how versatile they can be even when gifted as a Christmas present. I guess your Christmas bouquets get to be very variegated!

  2. Courtney says:

    Hi 🙂

    (I posted a question on your Grow your wedding flowers post ..)

    I want to try plant some dahlia’s so they can hopefully be ready earlyish April … if I planted them in pots what size would you recommend? And how many tubers per pot would you do, a few or one per pot? Also roughly how many flowers would one plant give? And (last question for now) when would you recommend planting them?

    Thanks heaps,


    • Hi Courtney
      You can plant your dahlia tubers as soon as they appear in shops – usually August/September. Though you’ve got plenty of time as your wedding is not until April. They will take 3-4 months to bloom, so September is a good month to plant. They will continue to bloom until April, but make sure you keep your pots in a sheltered spot in sun. If we get rotten weather around that time you might find they start to slow down, so it’s important to keep them in a warm, sunny spot. Make sure you pick or deadhead the blooms once they begin flowering so that they continue to produce more flowers.

      As for pots, a 26cm-30cm wide pot is fine but I’d only plant one tuber per pot so that each plant has their own space to grow, with no competition from other plants. Liquid feed your plants once a month once they start flowering. Any fertiliser will do – something like Yates Thrive for Flowers, or something like that.

      It’s hard to give an estimate on how many flowers per plant because in my experience each variety is different. I have some plants that are prolific flowerers (they seem to be white and pink and yellow ones) and some are not so prolific (these seem to be the deeper reds and maroons – the ones I like the best!). I have an orange one called New Baby that is extremely prolific.
      So New Baby will give you 30-40 blooms per plant, but one of my deep red ones will only give you about 3, although the blooms are much bigger than New Baby’s.
      If you aim for 3 blooms per plant (best to be a bit pessimistic) in flower when you wish to pick them, then plant according to that. If it was me, I would plant as many tubers as I could afford.
      I would also give some tubers to someone else to grow too (mother or friend) in case you find they grow better in one spot than another. And make sure you have some backup plants.
      Did you have a look at Dahlia Haven?

  3. Lynley Anderson says:


    do you have any Dahlia Titoki Point tubers to spare? I have been trying to get them for years! Unfortunately when I moved house about 12 years ago I did not take any of mine with me. I am of course happy to pay.


  4. Lynley Anderson says:

    Hi Jane,

    I have already tried Greenleaf Nurseries/Dandy Plants and although they advertise them they never have actually come up with any. And then they tried to charge me twice for something they did not even have in stock and could not get for me.
    It was such a mission to deal with them I am not sure I want to go through it again.

    I have contacted Keith Hammett directly and he is trying to take some cuttings for me.
    Wish me luck 🙂

    thanks for your help.

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