Climate resilient gardens, lettuces, and gladioli

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It's one of the most magical moments of the gardening year, full of anticipation with so much still to come. Of course it's still too early to say exactly what kind of weather this year will bring, but the bigger picture is becoming clearer. The data shows that summer droughts and winter floods are not only becoming more common, but more extreme. So what does that mean for our gardens and the plants we grow in them? This week we're speaking to Jenny Bowden from the RHS Advisory Service who's been working on an experiment to find out which plants can cope and even thrive in these changing conditions. We'll also be heading to RHS Wisley where Liz Mooney isn't wasting a moment. She's already sown the first of her lettuces, kicking off a summer-long lettuce extravaganza showcasing more than 80 different cultivars. We'll be harvesting some of her top tips very soon. And from the veg patch to the cut flower garden, we'll be turning our attention to Gladio Lai. Once a favourite of Morrissey and Dame Edna Everidge, these theatrical blooms are now making something of a comeback. Bulb expert Mohammed Hafizullah joins us to share his advice on how to grow them at their very best. All this coming up on Gardening with the RHS with me, Nick Turrell. The RHS is probably best known for its shows like the Chelsea Flower Show and its beautiful gardens around the country, but a big part of what it does also happens behind the scenes in its gardening science and research. Stationed up at the State of the Art Hilltop building at RHS Wisley are 130 dedicated people working to provide solutions to some of the great challenges we face and few are bigger than climate change. We caught up with horticultural adviser Jenny Bowden who's working on a new piece of research which will help us understand what plants will thrive in our increasingly extreme UK weather. Over recent years our climate has become more and more unpredictable and we get in advisory more and more questions about plants that will tolerate dry conditions in the summer and wet conditions in the winter. I mean over the past five years for example four of them have been the warmest since 1884. So we really need to plant with these extremes in mind so essentially what you plant when your garden gets very wet in the winter and when it dries out a lot in the summer time. The summer season is getting longer and so that gives us all sorts of problems with insects coming out earlier. We need plants for them to get nectar and pollen from earlier on and we need to make our gardens more resilient for the future because we're only going to have more of this. Plants that adapt themselves well to drought conditions there are certain characteristics that we can look for when we're buying plants. It's not so easy with the flood tolerant plants I have to say you don't always know by looking at them unfortunately whether they're going to be successful or not. First of all dealing with the drought tolerant ones is a lot more obvious things to look for. Obviously if you go into looking at the origins of the plants that's wonderful that's fantastic if you go back to the very root of it as it were and find out what conditions the plant lives in that is the golden standard but you can find out a lot just by looking at the plant. Certainly Mediterranean plants often have silver leaves they've got small hairs on them which will help stop transpiration that's water loss through the leaf. Sometimes the leaves are quite small or succulent as well sometimes the leaves will be quite resinous so the oils, resins, things like herbs that whole group of plants they're going to be very drought tolerant. Don't forget the bulbs, bulbs and rhizomes, corns, bulbs, tubers all of those types of underground storage organs can tolerate periods of dry weather. The other thing that might not be so apparent is tap roots. They can really plunge down deep and get to moisture deep, deep down. Going dormant a lot of Mediterranean plants will just go to sleep in the summer and lose their leaves and die right back. Think of cyclamen for example. And I think this is one of the things that we might need to think about for future is that gardens might not be quite as traditional with all the lupins and delphiniums. We might have to get a bit more used to the idea of things happening at the beginning of the season and then again at the end. For the wet conditions, especially winter wet, some plants can have adaptations like their stems have a mechanism called air enkeema which are like straws inside the stems which actually provide oxygen from the air to the roots because that's the problem when things get waterlogged, they're starved of oxygen. Sunflowers for example have that skill. A lot of plants that live by rivers have this where the level goes up and down. They're known as riparian species. Roots can be quite inventive in where they go. They can avoid water. They can put on extra roots just near the stem. They're called adventitious roots and they can kind of escape the moisture. The architecture of roots can change to adapt to the challenge. I mean the classic example of that is swamp cypress where they have these, they're called new metaphors which are like knees that actually come out of the water so that they can breathe. The two extremes actually dealing with wet winters and dry summers is really quite a skill because most plants can deal with one or the other. To do both is really quite impressive and so we're obviously very interested in what it is that allows plants to do that, what they are and where they come from and that's really what part of what our experiment will lead towards. We've had web pages on giving people lists of plants that they can put in their gardens that will tolerate wet soils and dry soils and the way in which we created that list was surveys but essentially it's all anecdotal which is fantastic because it's practical and it's from real gardeners but our science team always want scientific evidence and so we have taken a selection of those plants that I've found to be tolerant of those conditions and we're putting them into a more controlled environment to test them out and just see how much water they need to keep them on the straight narrow as it were and how they react to summer drought and how they react to being soaked in winter, in shade as well. We've got four model gardens if you like, each little plot is a metre square and we've got four plants in each and four different model gardens which are repeated. There's a lovely selection of plants, a lot of them were shore fire examples, others were quite interested to see how they fare but quite a few of them are really tolerant so among those I would really recommend Hardy Plumbago which delights in the name of Cerrita Stigma Plumbaginoides. So that's beautiful vivid blue flowers, it's a ground cover plant and it grows in full sun, also shade and vivid, a really unusual colour for the garden because it's such a vivid blue and that flowers late summer into autumn and you've also got fantastic red autumn shades in the leaves. We've also got Vibina, Vibina bonariensis which is a well known plant and it's a lovely airy purple flower which flowers all summer long and can be up to six feet tall, it's a lovely see-through plant so it's really lovely in the border. Roses have proven to be quite tolerant and we've chosen a ground cover rose, white flower carpet for example, you can get them in all colours, there's yellow, pink, white and red flower carpet and they're good because they've got a deep taproot so they tolerate the drought very very well as well. Helleballs, helleballs are wonderful because they give early colour in the garden for us and they keep the pollinators happy and they're very tolerant, surprisingly tolerant of summer drought. Climate change in the garden, I mean you've got to look at the positive side, there is no reason why planting should become more dull, I think it opens up options to us and it's a very exciting time to introduce new plants from areas of the world that actually do have these particular conditions anyway and have always had those conditions so I think another door is opening. Huge thanks to Jenny there, you can find links to our current recommendations for drought and flood tolerant plants in the show notes and we'll follow up with the results of the current study when the results are out. Next we're heading out of Wisley's hilltop and into the World Food Garden where Liz Mooney is getting stuck into one of the busiest times of the year in the veg plot. This week she's turning our attention to salads so we popped in to get some of her expert advice. Each year in Wisley I always like to try and push the boundaries and try new cultivars and one of the main ways I'm doing that this year is through what I'm terming my lettuce extravaganza where we're growing over 80 cultivars across the course of the growing season. It won't be 80 any single time but from March through to October November across that period will be over 80 cultivars and the reason I'm doing this is that lettuce does come in a huge range of cultivars and varieties whether you're looking at your red or green is obviously an obvious distinction but then you also have ones which are slightly more bi-coloured and then you have everything from your iceberg types, your cos types, your loose leaf cut and come again types, your butterhead types, there's just so much variety within them but I wanted to try and really showcase that to the visitors and maybe encourage them to try growing a type of lettuce I haven't tried before. When selecting the cultivars to grow as part of this extravaganza partly I chose a load of cultivars which I've grown before and I know are really reliable ones like Webb's Wonderful, Marvel of Four Seasons, Lomb Joints, Green Cards, just good old favourites but I also looked through the RHS AGM list of the award of garden merit list of cultivars and tried to get hold of as many of those as I could to showcase and then I also went on to the websites of some reliable seed companies like Thompson and Morgan and so forth and had a look at the lettuce varieties they had listed there and selected ones which I thought looked really nice. Some ones I'm excited to grow so I planted out the first of its extravaganza in mid-March and one which has already caught my eye is called New Red Fire with its lovely red looking leaves and I can't wait to see how that one grows. Lettuce is a great crop because if you sow loads at once you'll just end up a massive glut it's one that's much better to sow little and often throughout the season so you can keep that steady supply. We sowed the first seeds of these in sort of mid-February inside in the glasshouse and those are the ones I planted out in sort of mid-late March but I will be sowing and planting lettuce right through the season. The last lettuce I'll be planting out will be going out in sort of August time staying through until October November time. When you're growing lettuce you have a choice between direct sowing them outside or starting them inside. Now we're starting all of ours inside so we've got those slightly bigger plants that slightly more instant impact when we put them out in the garden and to do that we just open inside into modules or into a seed tray put them out, grow them on in little we use little sort of nine centimetre coir pots that are biodegradable so they grow in these pots and we can plant them out in the pots but I'm to disturb the roots too much. You can also direct sow lettuce and I do do that through the season it's quite a useful thing for trying to plug some gaps. To do that I would create drills in the soil and then lightly sprinkle the seed and cover them back over. You want to drill to be a couple of centimetres deep maybe it'll depend on which lettuce you're going and how you're planning to harvest them but something around the sort of 25-ish centimetres apart. The one thing I would say with direct sowing outside is if you happen to live in a location which has a major slug population it's probably better to start them off inside get them a bit bigger get them a bit more resilient before you plant them out otherwise you might just never see those little seedlings. We're lucky here at Wisley our slug population isn't too bad so we're able to direct sow and get away with it in terms of the slugs. Having mentioned slugs I do think we should go into them in a bit more detail because lettuces are one of their favourites. First thing to say is that slugs are part of the wider ecosystem of the garden so we don't want to be trying to eliminate them or destroy them we want to be trying to live with them and manage with them and with lettuce as I mentioned probably the best way is to start your lettuce off inside so they are a bit more resilient. It can also be a case of trying to grow lots of lettuce so you might lose a few of them but hopefully more will keep going and if you're in a particularly slug prone area I do I know somebody who grows all of their lettuce in pots so they can hopefully try and keep them closer eye on them and check the slugs that way. I mean all of the usual advice about slugs can apply in terms of trying to encourage them their natural predators and so forth into the garden to control them. I'm not going to pretend that slugs aren't an issue of lettuce but they are something you can try and manage and live with rather than wanting to eliminate. In terms of other leafy crops in the veg garden because lettuce is brilliant but you might want to add some variety into that there are plenty of other things you could be sowing in the same way so I would grow things like spinach in the same way, mustard leaves, even things like undyed they can be really good for some spring crops. Mustard, undyed, spinach I won't grow them so much through the summer because they can be more prone to rising to flower. Now flowering is not necessarily a problem you can eat the flowers and so forth but if you're growing it for the leaves then it's not what you're aiming for. Those are actually also crops spinach, mustard, undyed, I've actually overwintered all of those so we're really getting spring crops from them already in the world food garden at Wisley, we've already harvested from all three. Good cultivars of those if you're overwintering spinach, giant winter is a good one to look out for but we're also really good cultivars like Medinia, Lazio, Emilia, mustard my favourite by far is red giant it gives you these enormous really beautiful attractive red leaves. We've been picking for several weeks already and on dive you can get the straight species it's a really nice one to do. A variety called Panchellerie is a really good one so those are three other leafy salad crops that are really good for spring harvesting. As I mentioned maybe not so reliable as you go on into the summer but you can grow your lettuce through the summer just do be aware that lettuce germination when the temperature gets too hot can be impeded so they don't germinate very well so if it's getting really really warm then you're much better to try something like this outside maybe in a slightly shadier spot rather than trying to germinate it in the glass so they might just get too hot. I find lettuce, well I found all of these salad crops quite good things to recommend to people who are really getting into vegetable growing for the first time obviously only growing if you like to eat them if you do like them then they are good because they can germinate really quite readily for you and a lot of them they will give you this cut and come again harvest so that you so once a man can pick multiple times which could be really satisfying as a way to grow and you can harvest these leafy crops throughout the whole year if you manage them well swish charred as another leafy crop that's really good for that for harvesting through much of the year. Lettuce is one I personally don't grow through the winter there are some cultivars which are supposed to be more hardy through the winter density for example marveler four seasons I just personally find that I don't want that tweet lettuce in the middle of winter I'd much rather have the spinach and the slightly heartier crops but if you want to for something lettuce cultivars you can try through the winter months maybe keeping an eye on a bit of protection if the temperature is dropping too low. So if you fancy giving any of these a try do pop down at Wisley anytime throughout this growing season to see what cultivars we've got growing and to maybe get some inspiration for you we're going to be so many different ones so many varieties you can try. Someone's I'm particularly excited to try growing this year there's a green coz lettuce called chatsworth that I haven't grown before and I'm looking forward to growing another green lettuce a sort of more loose leaf type called black seeded simpson improved that we're growing and we're also red varieties maybe things like pig ale pills and things like that which is just a really cool name which just sticks in your head so do come along and get some inspiration. Huge thanks to Liz there stay tuned for more growing guides with Liz in the weeks and months to come and of course check out previous shows for even more grow your own goodies of course not everything we grow is destined for our plates some plants are grown simply to be admired in avars take gladioli their name comes from the latin gladius meaning sword and legend has it they were worn around the necks of roman gladiators for protection in battle since then gladioli have caught the eye of gardeners and artists alike with a particular surge in popularity in the 1970s and 80s when moracy of the smiths and dame edna average made them part of their signature style these days they've slipped out of fashion but with modern breeding bringing an even wider range of colors and forms there's a strong case for giving these showy flowers a place in today's gardens so to tell us more about this striking genus we're joined by muhammad hafizullah one of the judges from the recent gladioli trial and a member of the rhs bulb expert group my name is muhammad hafizullah and i live in the northwest i think my first encounter with gladiolis and other plants was at the rhs shows and that's how i got a little bit entangled with it i do show it a few regional shows it's a very competitive environment out there but i can enjoy that you know the prize money is not that good only three quids but at least you get a full bragging rights for one ear you know like who's the daddy that kind of stuff when you look at the gladiolis in general why would you pick this as compared to any other thing i think first of all is the drama i mean if you look at some of the colorful aspects of gladiolis you can have a spectrum of colors bosh colors and almost rainbow of colors they have a certain vertical architectural form with a fabulous bilateral symmetry and the way it grows and produces flowers is from bottom up all the way to the top i mean you could actually get good two weeks of flower display if you do cut flowers which i eventually got into i also look at the sustainability element of it because once you get your combs initially every year you will have a fabulous supply of heli combs for the next year and if you want to bulk up your supply you can even use the comlets you can also stagger planting succession planting so every other week if you plant combs successionally until probably middle of may starting from middle of april early april so you could have a literally a whole summer of display of plants and a beautiful colors that go with it what they cannot take is a frost so you've got to plan accordingly see the best thing to do is during the dark winter months you pick up a good catalog or two of gladiolis go through it and see what is it that you want to grow for the next season i mean that's that's initial start for people who have not grown gladiolis they come in different sizes scales colors you know so you choose what your heart tells you choose what what you feel is the right thing for you what i do during the winters i think about how would i rotate my gladiolis i think the most important bit if you're not using the pesticide and insecticide is not to grow gladiolis in the same corner every year because some of the diseases are soil born and they will stay in the soil for a few years what the gladiolis don't like is they don't like their feet in water and they want full exposure to the sun you want to plant them in a place where the wind is not going to affect them seriously because if you put it in a very windy place then you might have to stake your plants and it gets a little fussy if my larkman got some well-rooted manure i'll put that on the plot about a good three four inches thick but once i get into let's say middle of april i rake my soil up and i'm ready to go planting but before i do i need to prepare my combs a little bit if you're buying loose combs then i what i do is i pick the ones that are good firm and healthy looking because they have a husk on top but what you do is turn it upside down my experience has been that if you buy combs with a good size basil plate what a basil plate means is if you turn the onion upside down where the roots are coming out look at the size of that okay that is a good reflector of how mature the comb is so anything that's like two years old would give you a very good display of flowers i'll take them home and i take them out of the plastic bags because they need airing i leave them outside cool place but frost free okay take the husk out because some people well especially the beginners they don't like to mess about with the husk they just want to plunk it in my experience is that some of the residual pests from last years especially the strip might be still with the combs okay so you when you take the husk out clean it out this should be shiny plump no unnecessary holes in them you want to plump not a mushy when you take the husk out it should be shiny and it should have two or three growing spots what i would call the buds i spread them out leave them there and in first week of april i put them on a old newspaper with a little bit of water so that the combs get the idea that it's growing time now so they'll start producing some roots and in about a couple of weeks time i can put them in the ground then i plant them about six inches deep but the thing that the gladiol eyes don't like is to sit in water the thing you need to worry about is if you put in too much good stuff fertilizer especially the nitrogen paste you'll get a lot of lush green growth but at the same time you're making the plant wonderful to diseases fangals bacterial diseases because it is growing out of proportion so first couple years i did make that mistake and some of my gladiol eyes were almost seven feet high so i mean they're not supposed to be that high but i gave them too much nitrogen i shouldn't have done that but you know these are the things you learn from retrospect i do water them once a week if the weather is dry you know but if it has rained or anything i just don't bother about doing anything when all your leaves are out and you can feel the spike in the middle just before it comes out when you hold the plant in the middle you can feel a little something coming up in the middle and that is the time when i increased potassium basically a tomato feed a dilute tomato feed because that is the time when you want the flowers and the bud counts to go up as much as possible and the thing you need to worry about during the year is is the weather just before flowering i i make sure that they are well watered and they don't go completely dry other than that i don't think i mess about with the gladiol eyes at all once you see a color in your pots the bottom two ones and they're just about to open that is a good time to use them as gut flowers okay because then you can take them home or give it out or whatever to your friends and they will have a good 14 days of flowering period i tend not to cut too many leaves for the cut flowers i try to leave as many leaves as possible on the plant itself because what the plant will do is manufacture as much food for the new combs that is coming up and then just before frost i think when the leaves literally turning brown i'll probably dig one just to check and if i see a good healthy bulb then i'll pull them out and clean them and put them in a frost free place the thing is every year the gladiola develops a new comb on top of the old ones so when you dig it out you can see the old comb and the new comb coming up so you need to separate them too clean them cut the roots off and let them dry in your greenhouse and that is a good time to look at any infections but i think end of the day you got to have a garden that reflects you your personality your life events you know it has to come from your heart my favorites ester bonita is is is a good peachy colored amsterdam and that's another good white one careless is another good one get yourself a good catalog it all depends on what kind of colors do you like you know if you want taller growing or you want slightly shorter ones but if you look at the north american gladiola council they'll tell you exactly what size what color and if the center is of a different color so it's a very good site to visit so it all depends on your taste you see end of the day a big thanks to mohammed there well that's just about all we have time for this week so from me nick turrell goodbye and thanks for listening