Still learning about hollyhocks

I think every day I learn a little more about hollyhocks. The frustration with regard seed names and seemingly different hollyhock seeds turning out to be remarkably similar (by that I generally mean they look the same to my none horticulturist eye) is probably top of my frustration list, but are there any other myths that could possibly be dispelled?

Well maybe. Obviously most of this is opinion, and with all things, including gardening, we are all entitled to our own.

Firstly one of the things most often said to me are – aren’t hollyhocks a lovely old fashioned flower. Now I always take that in the spirit its meant, but then do have to come back as to the danger of fashion, particularly in relation to plants. If an article of clothing goes out of fashion (which often only happen to convince you to buy more stuff you don’t need) then 20 years later when it apparently is “back in fashion” you can make more. You can’t do that with plants. If one goes out of fashion… it doesn’t get sold. People don’t propagate it, and it can be lost forever. So when I hear about fashion and plants, I may challenge that view 😉.

Then I hear hollyhocks love growing in cracks in the pavement – something oh so helpful if you are trying to improve on a national collection. Now putting aside the confirmation bias – in that plants growing in cracks are rather more noticeable – so when we see them we then think thats the ideal growing situation and its where they prefer to be (shhhh They don’t) it perhaps does give us an idea as to what an ideal position will be like. For me my national collection isn’t in an ideal position. But its the position I have, and I have to work with it. I think the crack in pavement can tell us this. Hollyhocks develop a long atop root and can find their own water source. That is true for ones I have grown in unwatered ground in a hot polytunnel. The crack also shows that actually if there roots don’t rock in loose earth in the wind, thats also idea. And of course they don’t necessarily like their feet in water. So whilst they can grow in cracks, Ive currently got Cosmos, verbascum and a few other plants also doing that here… but I’d you keep telling me thats their favourite position I will just say OK, yes it must be.. and in a quiet voice whisper “It isn’t”.

Then I also get told they are just so easy to grow. Another comment often meant in a nice way, but not what anyone wants to hear having put blood, sweat and as of yet no tears into this endeavour. Without a doubt they are one of the easiest plants to germinate. But then they can be the moist awkward of plants. Rust is an ever present danger for which there is no cure. This year I have phenomenally managed to keep it very much at bay. This is in all honesty probably not down to my endeavours but by chance, even when I assumed the weather over the last few weeks was the prime conditions for it. They also are big old beasts and in windy positions can be prone to flopping, snapping and generally looking appalling if not staked or tied. That being said, they are hugely rewarding, but easy (as in not much effort required) is not always a description I recognise.

Having said all of this, I would advise anyone to have a go, because as mentioned above, they can be hugely rewarding. And of course, don’t let anyone put you off, because we should all grow whatever gives us a bit of pleasure.

What a difference 4 months makes

In April I started to get a bit worried that the Hollyhocks didnt seem to be coming back very well. When you think that as of today (In August) this national collection isn’t even a year old, the inability to compare anything to previous years was always a bit nerve racking.

Fast forward to August and the plot is full of flowers, and in actual fact I’m already collection seed off other hollyhocks on the plot. The weather has made it a strange year. At one point the plants were at least 2 weeks behind previous years. I have a video from less than a month ago when this plot hardly had a flower on any of the plants. Plenty of sun (mixed in with deluges and winds) means a month later and some of the hollyhocks are at their prime with others already well on their way to finishing.

Given what a jungle of growth it now is, I certainly shouldn’t have worried about not getting a decent display. But it’s easy to say that now. Without a doubt next April I will be worrying just as I did this year.

Hollyhock Rust

So many times I get asked “do my hollyhocks get rust”. Shhh – its a dirty word around here. I prefer calling it “the scourge” as it was in Victorian times. But as you can see from the photo above – yes rust is hard to avoid.

The RHS have published some good advice which is very much worth repeating below 👇🏻 We very much adhere to the view of fungicide use being a last resort. Interestingly in spit of what has seemed to be plenty of humid weather and downpours, our plants have had their best year in terms of lack of rust, or keeping it in check.

Hollyhock rust is a fungal disease of the aerial parts of the plant, caused by Puccinia malvacearum. It is spread by airborne spores. The disease will invariably develop on untreated hollyhocks, although it is worse during wet summer weather.

Leaves, stems and calyces (outer parts of the flower) can all be attacked. Heavy attacks stunt plants and reduce their vigour.

Symptoms

You may see the following symptoms:

  • Bright yellow or orange spots on the upper leaf surface
  • Reddish-orange to brown, lumpy, spore-producing pustules on the corresponding lower surface
  • The pustules turn ash-grey under conditions of high humidity, as airborne spores are produced
  • The disease tends to start on lower leaves and spreads up the plant
  • Severely affected leaves shrivel and fall, and plants are stunted and lacking in vigour
  • Pustules are also produced on the stems and calyx

Control

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.

Control of hollyhock rust is not easy, even when fungicides are used. Spores of the fungus can travel long distances, so will arrive continually from surrounding gardens and wild plants.

Non-chemical control

  • Check plants regularly and remove and dispose of affected leaves
  • Dispose of heavily infected plants
  • Do not use seed from affected plants
  • Monitor bought-in plants closely for development of symptoms
  • Hollyhocks will live for several years, but to reduce the threat from rust consider growing them as a biennial, discarded after flowering
  • If keeping plants for more than one flowering season, cut them right down to soil level in autumn, dispose of all leaf debris from around them, and be vigilant for the first rust symptoms in spring
  • Avoid dense planting as this will lead to high humidity around the foliage
  • Encourage good root development by avoiding over-wet or over-dry soil conditions
  • Control common mallow and avoid growing other plants in the Malvaceae family (e.g. Abutilon, HibiscusLavateraMalvaMalvastrum and Sidalcea) if hollyhocks are an important feature of the garden

Chemical control

The fungicides tebuconazole (Provanto Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect), and triticonazole (Fungus Clear Ultra) are approved for the control of rust diseases on ornamental plants, and can be used against hollyhock rust. However, regular applications will be required, particularly if the weather is unsettled. Target applications when they are most needed (start only after you see rust infection and then try to protect new growth) as the maximum number of applications allowed per year range from three to six, depending on the fungicide product. There will be little spread of the disease during prolonged dry spells.

The rust fungi are described as biotrophs; that is, they grow within the living tissues of the plant and extract nutrients from the cells. Although they do not kill tissues rapidly, heavy attacks by rusts can cause tissues to collapse and die prematurely and this is the case with hollyhock rust. 

The reddish-orange pustules on the leaf undersides contain numerous spores called teliospores that remain embedded within the leaf. Under humid conditions the teliospores germinate to produce a second spore type called a basidiospore. It is the production of the minute basidiospores that causes the pustules to turn an ash-grey colour, and it is these spores that are carried in air currents to create new infections when they land on other hollyhock leaves.

Infection is favoured by wet or humid conditions. The disease is therefore most problematic during wet summers, but it is so aggressive that plants are invariably affected even in dry years.

The fungus overwinters on the few green leaves remaining at the base of hollyhocks and perennial mallows, and may also survive within the crown of the plant. New leaves emerging in spring soon produce rust pustules. The fungus has not been found within the embryo of hollyhock seeds, but the seed could still carry infection in the form of spores on accompanying bracts or flower parts.   

Like many rust diseases, hollyhock rust has a ‘latent period’, when infection of the plant has occurred but symptoms are not yet visible. Depending on environmental conditions this latent period can range from a few days to several weeks. It is therefore possible that bought-in plants could be harbouring the disease. Plants grown on nurseries are often treated with fungicides, which may suppress the fungus without killing it. (Source RHS).

A week is a long time in gardening

The week started off with a seven hour photo shoot of the plants for a magazine feature – really interesting to see the techniques involved in plant photography

Then came some rather biblical rain storms.

Then the gusts came – but fortunately only one of the hollyhocks succumbed to the wind.

However what it does mean is the full day of filming which was due to take place on the plot has now been moved from tomorrow, which is looking once again distinctly wet, to Monday. The good news is it will save some time on watering.

Hollyhocks still coping with the “weather”

Its been an interesting time for the hollyhocks. The rust hasn’t been half as bad as it could have been, but the weather is always challenging, The ones in pots need watering when dry, and the doubles become heady in some of the rather large downpours.

20mph winds are predicted over the next couple of days so a few stakes and string have been put in place to stop some of the more likely ones from crashing down.

We need to talk about rust?

Perhaps the question I get asked the most about hollyhocks is what do I do to get rid of rust.

For me that’s not the way to approach hollyhocks. Manage your expectations and expect to get rust, and just think how you will manage it when it comes.

Using an anti fungal spray is one method that can help keep in in check – but I always use that more as a last resort given it can have an impact on pollinators. For me its about removing any infected foliage once you see the signs – and dispose of them, as opposed to putting on your compost pile which could just aid the spread,

There are of course rust resistant hollyhocks, but even those can and do get rust. Having removed any infected foliage some people think the plants look a tad strange – so why not just treat hollyhocks as a back of border plant, and add some under planting.

This way you are learning to live with what is an incurable disease as opposed to trying to totally cure it, which may leave you disappointed.

July 2021 – Halo Apricot

Quick tour round the gravel garden

Last year I finally finished this area of the garden, replacing old rotted out wooden raised beds, gravelling over what had become a rather unruly area and putting in these metal raised beds along with some galvanised planted.

This year its mainly hollyhocks and cosmos – with a few onions and garlic, just to stay true to the cottage garden style of growing your veg with your flowers.