Dahlias & 'mums'

[jethro]

I've just built 2 polytunnels  ;D 1 for Dahlias and the other for chrysanamums but as usual i dont know a thind about them :-[ :-/ sooooooo do i read lots of books on the subject :( or get all you educated people out there to help ;D. whoops sorry, the length of the tunnels is 20 yards x 12 yards. How many plants can i get in there ???.

Hope for some replies ;D ;D ;D.

[jethro]

[Mrs Ava]

okay....I shall impart all of my knowledge on you Jethro......

There you go.....impressive huh!  ;D  I know nout about growing these things, just curious really, as you are growing them in pollytunnels, are you growing them to show or for cut flowers or what???

[jethro]

Mainly for the wife as she loves them ;D, but i might try to show them :-/ will probably get nowhere  :( but will try anyway :P

[Hugh_Jones]

Hi Jethro. Are you going to heat the polytunnels from your wind turbine as well?

I`m afraid it`s 30 years or more since I grew `mums and at least 10 since I grew dahlias, so I`, way out of date with the varieties, but I can still remember the basics, and I still have all my old manuals.

I grew mainly late Exhibition and Incurved `mums, with a few garden varieties, and Decorative and Pom-Pom dahlias, as well as the Coltness Hybrids for bedding.
So..where do you want to start?

[jethro]

Hi Hugh, i'm not heating the tunnels, She Who Must Be Obeyed at ALL times wants the incurved & cactus varieties, (the size of dinner plates) also the pom poms (dahlias). ;D so any help with the soil conditions ie acid alkali would be helpful. Also what is meant by stopping the plant ???

Cheers Hugh ;D ;D

[Mrs Ava]

hmmm...doesn't stopping the plant mean pinching out the first flowering shoot to encourage lots of side shoots which will produce masses or flowers.......?

[Palustris]

Now I feel really old. I used to get a penny (pre-decimal) a bud for dis-budding 'mums. Never could bring myself to grow them though.

[Hugh_Jones]

Jethro, I`m afraid you`ve got me foxed on Cactus `mums - as far as I know there ain`t no such animal. Are you confusing them with cactus dahlias?  The big `mums are usually categorised as Decoratives and Incurves.

Are you going for the late flowering or the mid-season `mums?  I think you would be better with mid-season in a polytunnel.  Late flowering would be ok under unheated glass, but you might have problems with ventilation and condensation under poly in November - they`re b*ggers for mildew in damp conditions.

As to soil, I assume that you will be growing them in pots throughout since you`ll want them outside during the summer, and only bring them in to flower.  If so you simply can`t do better then good old John Innes - once the cuttings are well rooted in whatever medium you prefer pot them straight into J.I. no 3 in 10" pots.

As to acidity/alkalinity, the J.I composts traditionally work out at about pH 6.3, which is fine for pot growing.  If you want to plant in beds (probably not a good idea under poly) a pH level of 6.5 to 7 should be aimed for.

Stopping, as Emma Jane says, means taking out the central bud - not only to induce branching, but also to prevent premature flowering.  Some varieties need only one stopped once, others can be stopped twice.  However, if you want dinner-plate size, you will not want masses of flowering shoots - only 3 or 4 for the largest.  The dates for these operations depend entirely on whether they are mid-season or lates - I can give you more information when I know what type you are growing.

Unfortunately have to terminate here for the time being but will come back again re dahlias later.

[Hugh_Jones]

Back again Jethro.  Since my last posting I`ve been wondering whether your idea is to grow the `mums and dahlias entirely in the polytunnels, in which case I`m a bit out of touch.  In my growing days not even the exhibition specialists housed their plants during the summer, but only brought them inside from September onwards.. The plants are pretty hardy, you know, and only require protection from autum onwards.

As to Dahlias, you will presumably receive the tubers or rooted cuttings in late March/early April, when they should be potted up into J.I. No.1 or a good soilless compost in 6in. pots until they can be hardened off for planting out.  The soil requirements for final planting are pretty well as for most veg. crops.  A pH level of about 6.5 is ideal. Plenty of humus in the soil plus a good balanced fertilizer.  Occasional liquid feeds of balanced fertilizer throughout the early summer, changing to high potash fertilizer as soon as the first buds start to form.

I think you have enough there to start you off, but if you have any queries on what I`ve said so far don`t hesitate to come back, it does me good to get the old brain working occasionally.

[jethro]

Hi Hugh, get the 'old brain working' eh your just a young whipper snapper really. Right lets start :-/ the tunnel has mesh sides so ventilation shouln't be a problem. Sorry it was dahlias ( cactus) :-[ the reason i'm growing them in tunnels is that all the lads & lasses on the site that show them grow them in tunnels and have fantastic results ;D. They put paper bags over them to stop earwigs chewing them :P .

Another question ??? how far apart do you plant them to let the air circulate?

Heat the tunnel with the turbine? welllllll it's just might happen but, i will have to build a new one as the one i've got is not powerfull enough :-/ , it's only 5 watt.

[Mrs Ava]

Complicated just for some big blousey flowers huh  :o.  Mind you, I can see why people get addicted to growing them and showing them.  I adore Dahlias, not so into 'mums'.  Got me tempted I have to say.

[Hugh_Jones]

Back again Jethro. Mesh sides? Those aren`t tunnels, they`re umbrellas.  If you`d said that in the first place you`d have saved me 10 minutes typing.

Now as to Dahlias:-
Planting distances vary as to height, so you have to check your variety. Under outside conditions Large Decorative and Cactus require 3ft minimum each way. Medium varieties will manage with 6ins less each way.  Needless to say, your stakes should be firmly placed before planting, but as you`re growing for cutting etc and not for garden display you can simply wire the canes in lines with just a strong post at each end.  
Earwigs, admittedly, are a pest. Bred in the soil they climb up the plants or the stakes, and they can get inside a paper bag from underneath unless it is secured tightly around the stem (not recommended). Traps consisting of upturned pots full of straw or shredded paper on the tops of stakes will catch them but have to emptied regularly and the earwigs dropped into a container part filled with water with a thin layer of paraffin on top.  If hollow canes are used to support the plants the earwigs will hide inside them, and a few drops of paraffin will bring them out for destruction.

Chrysanths:-
I`m still not keen on permanently housing these in your tunnels, but if that is what you want to do prepare the soil with as much compost as possible, aiming for a pH of about 6.5 and using a balanced fertilizer a few days before planting out. Allow a 15inch square for each plant.  Supports should be in place before planting - the simplest method is 2 strong posts at each end of the bed; wires then run along the length of the bed attached to crossbars wedged behind the posts and lightly tied on and the height of the wires can be raised as the plants grow by simply sliding the bars up the posts; string tied across the wires will then form a wide mesh net through which the stems grow.  Once established the plants should be fed with balanced feed until the flowering shoots are established, when a specialist Chrysanthemum fertilizer should be used.
The biggest pest with `mums is eelworm.  It is vital to start with clean stock, and to remove and burn any `poor doers`
Stopping dates will depend on flowering time.  November flowering are usually stopped around the end of May/1st week in June and only the one stop used.  However plants rooted in early February, and growing very strongly, can be stopped twice - mid April and early June.  The plant will indicate when it is ready for a first (or only) stop by the appearance of shoots in the leaf axils, the centre bud is removed and only the number of side shoots actually required retained, all lower shoots being rubbed out - the same process being used with a second stopping if this is required.  Once the shoots which are to produce the blooms are established all side growths or side buds are removed and only the crown bud allowed to develop.  You would be best to use only one stopping at first until you have more experience of growing and flowering unless you experiment on just a few plants.  I think December flowering would be too late without heat in your tunnels, so little point in dealing with that. However, has it occurred to you that your turbine might well drive a low power fan? This would give a big boost to the ventilation on hot days in summer and on damp nights in the autumn.

Anything else, just ask

[jethro]

Cheers Hugh, printed off your reply and put it in the lottie shed for future use and advice, i've heard about the 'pot method' of getting rid of earwigs.
Any advice on the latest development on the turbine 'thread'? or should i just shoot myself now?

[The gardener]

A big subject !

I grew Chrysants & Dahlias for years,I even had a go at exhibiting them. I still grow around 150 sprays and a few pot mums each year, have given up with the Dahlias.

As I said its a big subject so perhaps if I were to direct you to the Chrysant & Dahlia pages in my website it would save me a lot of typing here, particularly as I only use one finger and one thumb when typing  ;D

In there is the summation of around fifteen years of growing them

http;//thegardenersalmanac.co.uk

[Muddy_Boots]

Your wife has very good taste Jethro!  Mums have the most wonderful smell, always makes me think of gardens!  Also, they must be one of the longest lasting cut flowers around!

Kate