Tag: over-wintering

Checking and Re-Potting Over-Wintered Dahlias

August 2016 Dahlia Esther Chamberlain
Dahlia ‘Esther Chamberlain’, a personal favourite

A timely reminder from Monty on last week’s episode of Gardener’s World sent me down to the greenhouse yesterday afternoon to check on our stock of over-wintered Dahlia tubers.

Dahlias are perennial plants that over-winter by storing sugars in large tubers below ground. But these tubers aren’t particularly frost-hardy or water-proof, so they do require protection to get them through the wet British winter. So they were dug up, dried out and potted up in spent compost last November, just after the first frosts killed off the foliage.

They’ll soon (hopefully) be bursting into new growth, which makes now the ideal time to check them over and make sure they’ve survived their winter hibernation intact. Here’s how:

1. Quick Visual Check

March 2018 Dahlia tuber
Tip out your tuber, compost and all, for a quick once-over.

Start by tipping the Dahlia tuber clusters out of their storage tubs, and have a look for any obviously rotten, shrivelled or split tubers. Remove those, either by very carefully cutting them away with a sharp knife, snipping with secateurs, or gently twisting the affected tuber, which carries less risk of accidentally damaging healthy tubers.

2. Manually Check Every Tuber

March 2018 Dahlia tuber checking
Give every tuber a firm squeeze to check for non-obvious softening, or outright rotting.

It’s important to check every singly tuber in the cluster, in case there’s one that looks fine but is actually rotten beneath its skin. Give every tuber a squeeze to make sure it’s firm and healthy, once again removing any of them that aren’t.

March 2018 rotten Dahlia tuber
If a tuber is rotten you’ll quickly know about it, so don’t squeeze too hard…

You’ll soon find out if a tuber is rotten. Luckily, squishy tubers don’t seem to smell all that bad, but there’s always a risk of squirtage, so don’t squeeze them too hard…

3. Clean Up and Re-Pot

March 2018 Dahlia tuber cleaned up
Remove the rotten or damaged tuber sections and re-pot the remaining plant.

Once you’ve cut, snipped or twisted off any dead or diseased material, you should be left with a clump of healthy tubers, attached to a section of stem. At this point, you can also divide large clusters of tubers. Sometimes they split and separate during the checking and cleaning process. Otherwise, a bit of gently pulling might reveal a faulty line that you can take advantage of.

As long as the section you break off includes one or more storage tubers and a section of the stem / growth node part of the plant, then you should be be able to pot it up and grow on a whole new Dahlia plant from it. We started off with five or six bought-in tubers and over the past couple of years have increased our stock to around two dozen plants.

Re-pot each tuber into a mixture of spent and fresh compost. You can use all-fresh compost, which isn’t a bad idea if you’re planning on keeping the Dahlias in pots year-round, but I’ve found found that if you’re planning on planting them out when all risk of frost has passed then a 50:50 mix of spent – you can re-use the over-wintering compost – and fresh is fine. Once the plants go into the ground they’ll be able to draw on the nutrients in the soil.

Hopefully your efforts will be rewarded with a glorious display of dazzling Dahlias from mid-summer right through to Autumn!

July 2016 Dahlias Top Mix 'Mama' and 'Purple'

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Over-wintered and Spring-Sown Broad Beans

August 2016 broad beans
A selection of tasty broad beans – ‘Red Epicure’ and ‘The Sutton’

Successional growing – staggering the sowing and planting of crops – is a great way of to extending the harvest over a longer period and avoiding those “help, I’ve run out of chutney recipes” gluts.

It tends to work best either with fast-maturing crops like salad leaves or radishes which, with a bit of experience and also luck, can be sown every few weeks so that just as one batch has been harvested, the next ought to be ready to pick. But it doesn’t always work for slower-growing crops, which can often just sulk when the weather is poor and then put on a burst of growth and catch up when the weather improves. I’m thinking beans, courgettes, that sort of thing.

Another successional method, which does work well for slower-maturing crops, is to extend the season by over-wintering hardier varieties; sow and plant out in autumn, provide protection against winter frosts and/or rain, then watch them grow like the clappers as soon as spring rolls around.

Last year, we tried over-wintering a batch of broad beans. We planted out 20 ‘Aquadulce Claudia’ – a recommended hardy variety – under enviromesh, and only lost two to the winter weather. Here they are just a week or so ago:

May 2017 overwintered broad beans
These bean plants are much further on than their spring-sown cousins.

They’ve already flowered and are setting beans, and we’ve been picking the leafy tops as a bonus veg crop as well.

We then sowed another batch – this time a mixture of ‘Aquadulce Claudia’, ‘The Sutton’, ‘Rd Epicure’ and a mangetout variety called ‘Stereo’ – and planted them out in mid-April. Here they are in a pic taken at the same time as the above:

May 2017 spring-sown broad beans
These spring-sown broad beans will come in later than the overwintered ones, extending the season.

They’re just about starting to flower but they’re a good few weeks behind the over-wintered batch. That should mean the beans are ripe much later, so we might have had a chance to eat all the over-wintered ones before the new ones are ready.

Other crops with cultivars that over-winter well, or that can be harvested in the winter months, include onions, cabbages, kale, leeks, peas, sprouting broccoli, brussels sprouts, parsnips, carrots and of course garlic. We always plant our garlic and elephant garlic cloves in September as a couple of sharp winter frosts will help the bulbs to form properly. The same goes for strawberries; the best time to plant them out is in the Autumn.

How about you? What have you over-wintered from last year and is it doing well? Let me know via the comments, below.

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Dahlia Update: Lifting Tubers for Winter Storage

This was the first year that Jo and I have grown Dahlias and we’ve both thoroughly enjoyed the collarette varieties that we bought from J. R. G. Dahlias back in March – ‘Don Hill’, ‘Christmas Carol’, ‘Top Mix Reddy’, ‘Top Mix Mama’ and ‘Top Mix Purple’ – and the extremely lovely, deep purple-flowered ‘Esther Chamberlain’, which was a gift from Jo’s Dad, Guru Glyn.

We started them off in the greenhouse in April and planted out in May. They’ve been performing incredibly well since they first flowered in early June. We’ve had an absolute riot of colour, particularly from the two larger varieties, ‘Don Hill’ and ‘Christmas Carol’, as you can see from these pics (click a thumbnail for a larger image).

But the first hard frost of the year hit us last week and we knew that the time had come for these Mexican beauties to die back. So at the weekend, Jo and I nipped down to Plot #59 to lift the tubers and prepare them for storage.

As you can see, they were definitely feeling the cold:

November 2016 dahlias frost-bitten
Our dahlias were definitely looking sorry for themselves when we arrived.
November 2016 dahlias frost-bitten
In close-up, you can see the extent of the damage: blackened foliage, dead flowers.

After compiling notes gathered from various sources – Guru Glyn, Jack Gott’s website, Monty Don on Gardener’s World – here’s how we went about the job. If you spot anything amiss, or can think of a better method that we could employ or apply next year, please do shout out in the comments, down below.

1. Cut Back Foliage

With a nice, sharp pair of secateurs, we trimmed back all the leaves and stems, until there was just 15cm or so – maybe a little more, it’s easy enough to trim down further later on – of stalk remaining:

November 2016 - Dahlias trimmed
All the dead and dying foliage is cut back to around 15cm of stem.

2. Loosen Soil and Lift

Next, we worked a fork in around the plant, gradually loosening the soil in a circle that stayed well clear of where the main mass of tubers was likely to be:

November 2016 - lifting Dahlias
After gently loosening the soil, the entire plant is lifted out of the ground.

Once the soil was freely-moving, the entire plant was carefully raised up with the fork, taking care not to damage any of the tubers that hadn’t already snapped off. (The ‘Don Hill’ tuber clump was so massive that it neatly split itself into three sections whilst lifting; so that’s two plants for the allotment next year and one to take down to Guru Glyn as a return prezzie.)

November 2016 - Dahlias lifted
The plants have been carefully lifted and are ready to be cleaned up a bit.

3. Clean and Crate up for Transportation

We carefully brushed off as much loose soil as we could. Luckily it hadn’t rained much recently, so the soil was moist but not claggy and we were able to get a lot of it off:

November 2016 - Dahlias brushed off
We brushed off as much of the loose soil as possible – no point taking half the allotment back home with us.

Once we were happy that we we’d cleaned them as much as we could without risking damaging the tubers, we put the plants into plastic crates for the car journey home:

November 2016 - Dahlias crated
The trimmed and lifted plants are crated up and ready to transport back home.

The next job will be to wash off any remaining soil and then thoroughly dry the tubers. Standing the plants upside-down on their stems for a few days will make sure that all the moisture drains out of the stems and doesn’t soak the tubers instead.

November 2016 - Dahlias drying
Back home in the greenhouse, ready for drying out before packing and storing.

The last stage will be to pack them in used compost (or I think we could use a compost / perlite mix) for over-winter storage in a cool, dark place. We have an old bedside table or two in the shed with good, deep drawers that should be ideal for the purpose. We’ll give them a check-over every fortnight to make sure there are no signs of rot.

Assuming all goes well, in four months’ time or so they’ll be ready for potting up in the greenhouse and encouraging back to life for another stunning display next Summer and Autumn.

Of course, now Jo and I have been bitten by the Dahlia bug, the trick will be to avoid buying too many new varieties to add to our selection. But then, when does one more Dahlia tuber become a Dahlia tuber too many? We’ll leave you to ponder on that little bit of horticultural philosophy.

If you’ve grown Dahlias this year, please feel free to share your pics on Twitter @nftallotment. We’d love to see them!

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