Dahlia's in pots?

I have been given 7 dahlia tubers, no idea on the exact variety.

I've been reading about them and am a bit daunted about digging them up each winter so wondered if it would be easier to plant them in pots then I can easily remove them from the pots over winter rather than digging into the ground.

Would this be feasible? If I planted them now into a pot should I keep the pots in the garage/shed until the last frost has passed or will they be OK outside now?

Should I also just plant one tuber per pot or if I have a large pot 38cm diameter could I get a couple of tubers in? should I plant something else on the surface as well or will the dahlias look lovely alone?

Apologies for the q's i'm clueless! thanks for any help.

 

Hi HampshireNovice. Its actually very easy and quick to dig them up from a border. Personally I would think that was less trouble that putting them in a pot.

However, they will grow quite happily in a pot (like most things). But I would use as large a pot as possible, and I wouldn't want to put more than one in a pot, unless the pot was huge. At the end of the season I dig mine up and the bunch of tubers, which are all connected to a woody crown at the top from which the stems grow, may well be over 30 cms across.

The other point is that Dahlias like lots of water, so you must be willing to water the pot a lot.

 

Hello Hampshire Voice. Dahlias are not frost hardy so are not safe until after the last frost. You can put pots out before then to start hardening them off ready to live outdoors as long as you keep an eye on the weather and take them in or cover with fleece if frost is expected.
If you grow them in pots you can just let the pots dry out at the end of the season and lift the pots into a shed for the winter.
If you plant them in the ground they might get through the winter allright. It depends how much rain you get and how well drained the ground is. I leave mine in the ground and about 50% come back the next year.
Since you don't know what variety they are you don't know what size they will be but I would think you would only get one in the pot you are talking about. You don't need to plant anything else with it as they are lovely on their own. If you deadhead them regularly they will flower to the first frost or until they run out of daylight in November.
If you want to give it a try bedding dahlias are very easy from seed - I just grow mine from seed every year, it saves all the overwintering bother.
Good luck and hope you get a geat show.

 

I posted some points about Dahlias a while ago. after reading a book by Gareth Rowlands. So I thought it might be worth repeating here.

Ten things you didn't know about Dahlias.

1) Garden and exhibition Dahlias are all given the name Dahlia x variabilis. This is not the name of a species, but just a posh way of saying that they are all complex hybrids and that no one can be sure of their parentage. There are 27 species (ie types that occur in the wild) but they are all weedy and not seen in gardens.

2) Dahlias come from Mexico and Central America, where the tubers were eaten in the past.

3) Dahlia tubers should be started into growth in spring by putting them in a box or a pot and half covering with compost with a little moisture. and given heat. There is no evidence that light is needed. So you could start them in the airing cupboard or in a heated propagator or just laid out in a sunny place. When the growth is about 4 inches high you can plant them out, typically 8 inches deep. But remember the foliage will not take any frost.

4) Dahlias have strong leading tip (apical) dominance. This means that the leading tip produces chemicals that inhibit side shoots. So you need to pinch out the tip to get bushy plants. If you pinch out the tips you will get a large number of smaller blooms. If you pinch out the buds on the side
shoots you will get a smaller number of larger blooms.

5) Dahlias are 95% water and need lots of it. They need the equivalent of 18 inches of rain during the main growing season, which is more rainfall that the wettest parts of Britain. So keep watering them even in the rain. Even in damp soil, during hot weather the plants could droop as their folige may be losing water faster than their roots can draw it up.

6) Once a bloom is the size of a pea, it is fully formed. That is to say it has the same number of cells as a full bloom. All that is needed to go from a bud to a bloom is the uptake of water. So keep watering.

7) Dahlias actually grow more at night than during the day. Like all plants they use sunlight, water, and carbon dioxide to photosynthesise, making sugars and starches. These are then transfered to where they are needed and burnt to produce the energy for growth. As long as there are enough sugars this burning process will continue at night, using up oxygen and giving off carbon dioxide.

8) Most Dahlias are short day plants. This means that they will only start to flower when the day length shortens. The longest day length in London is 16 1/2 hours on June 21st. But most Dahlias won't flower until the day length is less than 14 hours. This means that many Dahlias won't start to flower till mid August, irrespective of how early you started them off.

9) In autumn, dig plenty of organic material into the ground to improve its water retention. It doesn't matter if it is only partly composted. Don't feed when you plant the tubers in spring. The roots must be encouraged to seek out water. When the Dahlia is growing strongly you can give it a high potash feed, but don't overdo it. Cut back any feed when it is well into the blooming period. Only water turns buds into blooms, so feed will not help - it will just produce more foliage. At the end of the season, a high potash feed will help to make firm healthy tubers again.

1O) Lift the tubers just after the first frost has killed the topgrowth. Store them overwinter at 4C to 7C in a fairly, but not totally, dry place. The actual storage medium doesn't matter. It could be old compost, sand, shredded paper, under old sacks etc.

 

I tried one in a pot last year, first time growing Dahlias. They did fine to start with, flowered well, but not as long as they should have and I got fed up watering them constantly.

This year it'll grow in the border, I hope.

 

In addition tothe above fabulous advice I can only add that the taller varieties need a support structure. One of those meshes on canes work well.

 

Thanks for all of your advice, very helpful

I think i'll try and experiment with some in the ground and some in pots, just need to convince husband to dig them into the border at some point.

Here's hoping they grow.