The Garden in April 2024- ‘Between the Showers’

By April we are well and truly into spring and as such it is surely one of the most exciting months of the year. Helped by longer days and higher angles of the sun as well as the often dramatic April showers the garden suddenly begins to look vibrant and alive and we gardeners can be inspired by the colour from flowers and foliage and a variety of lovely scents. It is also, of course, a time for more activity on our part with the lawn to cut, weeding to be done, dead heading to be started and vegetables to be sown and planted.

In April, like most of the growing season months, it is almost impossible to chose just five plants that I wouldn’t want to be without and I have no doubt that your five are likely to be completely different. From the bulbs I have gone for the Snakeshead Fritillary (Fritillaria meleagris) with its nodding heads and beautiful markings. In the pond the stand out plant in April is the Marsh Marigold (Caltha palustris) with its masses of bright, golden-yellow blooms.

A white form of Fritillaria meleagris  //  Caltha palustris

From the climbers I have chosen Clematis alpina and C. macropetala with their lovely, nodding flowers in pinks, purples and blues and scrambling habit. In the shrub section I have gone for the spring flowering Viburnums such as V. x juddii, V x burkwoodii, V. carlesii and V. x carlcephalum with their highly scented, rounded and white to pink flower heads made up of masses of small, tubular flowers.

Clematis alpina ‘Constance’  //  Viburnum x burkwoodii ‘Compact Beauty’

Finally, from the trees I have chosen the fabulous, ornamental Cherry as I can’t imagine mid-spring without them. As I have mentioned many times before ours is Prunus ‘The Bride’ with its small, pink to white flowers which as I write are full of very happy bees. However, there are many others to choose from including P. ‘Okame’ and P. ‘Pink Shell’.

                                             Prunus ‘The Bride’

Looking back through past April blogs I see that in April 2021 I was singing the praises of a whole range of good spring plants including the five mentioned above as well as other favourites such as Brunnera, Myosotis, Chaenomeles and Magnolia. There was also a ‘jobs’ section including lawn care (more on this later), preparing beds and borders, seed sowing and planting. In April 2022 the blog came from the gardens at Aberglasney which this year are celebrating twenty-five years since the gardens were rediscovered and renovated. Can it really be twenty-five years since we all watched that series of wonderful programmes on the BBC- ‘A Garden Lost in Time’? As part of the celebrations a special screening of the programmes will be held at the gardens in the summer- details on the website. In 2023 the blog and talk for April was on ‘Beds and Borders’ and included definitions, preparing the soil, types such as ‘herbaceous’ and ‘mixed’, design ideas concerning shape, size, planting heights, group planting, plant forms, texture, colour and succession. In addition to these three ‘monthly’ guides there are also some ‘to do’ guides in April 2020 on ‘Taking Cuttings’, ‘Sowing Seeds for Summer Colour’ and ‘Growing Flowers for the house’ and in April 2021 ‘Growing your own Fruit and Vegetables’. All these can still be found on the Old Railway Line’s website under either ‘Monthly Guides’ or ‘Garden Tips’.

Moving on to the main topics for this month I will start with something that most gardeners are thinking about at this time of year- lawn care. April is a really good month to start to get lawns back into good condition following the wet and cold of the winter so that they can look their best for the rest of the year. There are, of course, different types of lawn from the striped, green sward of a formal lawn, the curved shapes of a more informal design, to the rougher grass under trees or shrubs. Lawns also have many different functions such as showpieces in their own right, a foil for colourful beds and borders, a playing surface for children or a soft area for relaxing on. Grass is the main plant of choice for lawns as it is visually appealing, pleasant to walk on, tolerates wear well and may be cut to a low level without being damaged. Other plants can be used such as Chamomile and Thyme but they are much less hard-wearing than grass. For this blog I am going to concentrate on lawn care rather than creating a new lawn although April is certainly a good time to do so either by seeding or turfing. For our lawn in West Wales the first job in spring is do deal with any moss which has appeared over the winter. In some years this is a fairly minor problem and can be dealt with by simply scarifying the areas concerned and removing as much moss as possible. It is not a good idea to add this to the compost heap/bin as it tends to reduce the speed of decomposition so ours goes into the ‘green bin’ for recycling on a larger scale in much hotter heaps. In other years, and I am afraid this is one of them following the mild and very wet winter, moss is much more of a problem and needs to be dealt with by killing it off prior to raking it out. There are a variety of products on the market for this purpose, some as part of a multi-purpose spring lawn treatment which also contains fertiliser and weed killer and some which are purely moss killers including the traditional treatment of Lawn Sand. Most are based on Ferrous sulphate which in a couple of weeks kills and turns the moss black which then needs to be raked out. This year we are trying out a non-chemical concentrate called ‘Moss Off’ by VivaGreen which is safe for children, pets, plants and pond life. It works by forming an invisible coating on the moss which stops its growth and eventually kills it. It will probably take a bit longer than the other treatments and will still need to be raked off and removed. I will let you know how it works out! There is another product on the market, albeit rather expensive, which claims that the dead moss decomposes in situ which benefits the soil and requires no raking. We may have to try this if the chemical-free method is not successful. All these methods of moss control are only short-term solutions and in the long run it is much better to deal with the conditions which lead to moss growth. There is, of course, nothing to be done about the winter weather but there are some ways of making the lawn less attractive for moss growth and these include reducing soil compaction, improving drainage, maintaining soil fertility to encourage strong grass growth, not mowing too closely and providing sufficient light. Several of these are dealt with in the next part of the lawn care process starting with scarifying/raking. This is aimed at reducing the build-up of ‘thatch’ and allowing both air and water to enter the lawn surface more easily. Thatch is organic matter consisting mainly of decaying leaves and stalks of grass which accumulate on the surface. A certain amount is good for the lawn in that it eventually decomposes to produce plant nutrients, reduces water loss through evaporation and helps protect the lawn from wear but anything over 1cm/half an inch deep can prevent water from reaching the soil and roots beneath. For smaller areas scarification can be done by hand following a cut of the lawn by working in two directions at 90 degrees to each other. It is quite hard work and is perhaps best done in stages but it works wonders for the stomach muscles! For larger areas and/or older gardeners it is probably best done by machine. It never ceases to amaze me how much material is generated by this process and I’m afraid that the collection process is just as hard as the raking. As long as there is not too much moss in the material some or all of it can be added to the compost heap/bin but it must be mixed really well with other waste plant material. At the end in order to make the lawn look a little bit better and to collect the last of the material generated I like to give the lawn another cut. Following this in order to get air and water further down into the soil allowing for deeper root growth and improved drainage generally the lawn needs to be aerated in some way. The simplest method, but still hard physical work I’m afraid, is by spiking with a garden fork. The fork is pushed into the turf to a depth of 3-4 “(8-10cm) and then angled slightly back to raise the turf a little without breaking it up. A more effective, but time consuming, method is to hollow tine/core the lawn either by hand or machine. This removes some of the thatch, aerates the soil and reduces soil compaction all in one operation. The aim is to remove cores of grass and soil from all over the lawn to create holes which are then filled by a top dressing of medium sand, sieved soil and a peat-free organic material. This prevents the holes simply closing up again and allows air and water to penetrate more easily. The cores themselves make a wonderful loam soil once the grass has broken down. Following all this physical maintenance work which can also be done in the autumn if preferred the lawn needs a feed in order to help the grass recover. It may also need some bare patches resowing and, if a lot of scarification has been done, the whole lawn ‘over-seeded’. This is where seed is just broadcast over the whole area to help renew and thicken the grass growth. Grass seed basically comes in one of two types- with rye grass for a harder wearing lawn and without rye grass for a finer lawn. There is also a special mix for shadier areas although I have to say that generally the better the light levels the better the lawn is ie. more grass and less moss! Some lawn feeds actually contain grass seed as well as weed killer and/or moss killer, others are just fertiliser which does need to be suitable for the time of year. Spring and early summer feeds need to be high in nitrogen to encourage strong grass growth while autumn feeds need to be lower in nitrogen and higher in phosphorus and potassium for strong and healthy root growth. Feeds with the extra components generally come in granular form while feeds on their own can be granular or liquid. Liquid applications do get to work straightaway but take a lot more time to apply. I find the granular form easier to use either by machine or by hand. Once all this hard work is done the lawn, unless it is a rough grassland with wildflowers which is cut in late summer to allow the plants to seed naturally, just needs regular mowing starting off with a high cut in March and April then a lower cut through May and June when grass growth is rapid and finally raising the cut in July and August to help the lawn survive the rigours of a hot, dry summer- if, of course, we get one! Just one final point, if all this seems too much like hard work just do one thing to make your lawn look so much better very quickly- define/cut the edge, it makes such a difference!

From a task which most gardeners do at some stage I move on to growing a plant which few gardeners attempt in this country- the fig. Figs, Ficus carica, are amongst the oldest fruits in cultivation. They have a very short chilling requirement of 100-300 hours below 7 degrees Celsius (contrast this with apples which require at least 900 hours below 7 degrees!) and thrive best in regions with a long, hot growing season. As a result, to fruit well in our temperate climate figs require a sunny position and in cooler areas a south facing wall or fence for more warmth and shelter. They also fruit better if the root is restricted either in a pot or in a brick or concrete pit which is around 2’ (60cm) square and deep with a base of broken brick or stones to a depth of 1’ (30cm) below that to improve drainage and restrict the downward root growth. In cooler districts pot grown plants need to be brought into frost-free conditions for the winter. In spring a mulch of well-rotted manure or garden compost is a good idea as is a light feed of a balanced fertiliser in the early summer. It is important though not too over feed which just encourages leaf growth at the expense of fruit. Watering of restricted plants is essential in hot, dry spells. Pruning in spring is mainly a case of cutting back frost damaged shoots to healthy wood and thinning out over crowded or ‘wrong-pointing’ shoots. In the summer the tips of new shoots should be pinched out when they have  developed 5-6 leaves. In warm climates figs will normally produce two crops a year, an early one from embryo figs (about the size of small peas) formed late in the previous summer, followed by a main crop which is formed and ripened during the same summer. In cool climates, however, only the first crop of embryo figs from last year will have chance to ripen. Any un-ripened figs ie beyond the embryo stage from last year should be removed in the spring and any un-ripened ones from the current year removed in the autumn. This helps to concentrate the energy of the plant on producing new embryo fruits which will hopefully fruit in the next year. Figs are best picked when they are fully ripe and eaten fresh. Ripe fruits tend to hang down, are very soft to the touch and may have slight splits in the skin. I hope you get to this stage!

As far as pruning is concerned April is a good month for finishing off any March pruning of summer flowering shrubs such as Buddleja, Lavatera, Leycesteria, Fuchsia and Sambucus but is also, in my opinion, the best time to prune Hydrangea and Penstemon which can both be damaged by late frosts if pruned too early. Hydrangea pruning for Lacecaps and Mopheads is basically the removal of the old flower heads down to a pair of strong, healthy buds or leaves just below. If the bush has become too large for the space it can be pruned much lower down but this will reduce the amount of flower for that year. Other Hydrangeas such as H. paniculata should be pruned much lower down to within one or two buds of last year’s growth. Penstemon in mild winters such as the one we have just had usually have a lot of top growth in April which has been protecting the new growth below. Most of this needs to be removed otherwise the plant will become too large and sprawling cutting back to new, healthy growth near the base. The best looking, newest tips of the cut material can be used as tip stem, softwood cuttings as discussed last month.

Over the last few years I have written and talked about spring flowering bulbs many times but I have to admit that I have rather neglected the summer flowering bulbs for which April is the best planting time. These are really useful in pots on patios but are especially good, in my opinion, within mixed beds and borders in that they come in a range of bold, rich colours, have interesting flower shapes and scents and between them can provide flowers from June through to September and sometimes beyond. They also tend to have tall flower spikes or stems which grow up through the foundation planting to provide, literally, highlights of colour and contrasting heights of planting. They are not all true bulbs, some are tubers, others are corms, but they all fall into the group which we have discussed before- bulbous plants meaning that they have a mechanism for storing energy and nutrients over a dormant period. Many are widely grown such as Camassia, Gladiolus, Allium, Crocosmia, Lilium and Dahlia, others are perhaps less well known such as Galtonia, Ornithogalum, Tigridia, Eucomis and Crinum. Allium and Camassia are planted in the autumn along with the spring flowering bulbs but can still be bought and planted in the spring as pot grown plants. The rest can all be planted in mid-spring and all enjoy, as you would expect, a sunny position in well-drained soil. Those such as Dahlia, Tigridia and Eucomis are more tender than the others and traditionally are lifted in the autumn and stored over winter in frost-free conditions. ‘Summer’ bulbous plants actually flower over a long period starting early in the season with Camassia closely followed by Allium and then the true hot season plants of Gladiolus and Lilium and in the late summer the wonderful Dahlia. However, it is possible to continue this succession of exotic flowers into the autumn with the Nerine from South Africa, autumn Crocus and Colchicum (Naked Ladies). Nerines need to be planted in July but April is a good time to lift and divide any over-crowded clumps. Autumn Crocus and Colchicums are best planted a little later in August.

I am going to finish with a rather specialised form of gardening which is especially attractive to people like myself who love trees but haven’t got enough room in the garden for more than a few small ones! This, of course, is the art, and it is an art, of growing bonsai. Although bonsai is a Japanese word it is recognised throughout the world as something to do with growing miniature trees in pots. ‘Bon’ is actually a shallow tray or container and ‘sai’ is a plant or plants. For me a better translation would be ‘a tree or shrub trained or pruned in such a way as to resemble a full-sized tree and grown in a shallow container for artistic effect’. There are several common misunderstandings about bonsai including that the trees are stunted in some way or are from special miniature seeds, that they are damaged by the training techniques, that they are starved of nutrients and that it is cruel- none of which are true! The three main techniques used are pruning/pinching the top growth, root pruning and wiring. The first two are perfectly normal techniques used by almost every gardener at some time. The third is admittedly more specialised and can damage the bark of the tree but only if left on too long. Between them they can create an impression of a living, healthy, mature or even old tree as would be seen in the natural world.

Crab Apple in Informal Upright Style    //    Cedar in Literati Style

There are three basic elements to any bonsai- the trunk, the branches and the exposed roots. The trunk should taper towards the top, the branches radiate like a spiral staircase around the trunk starting around one third of the way up with the longer, thicker, heavier branches lower down and either horizontal or downward sweeping and any exposed roots should radiate from the trunk to give the impression of stability and maturity.

There are five basic bonsai styles all based on the angle of the trunk to the vertical.

Formal upright- a straight, vertical tapering trunk.

Informal upright- a curved, sinuous trunk

Slanting-  with the trunk at an angle of more than15 degrees from the vertical like a wind shaped tree

Cascade- where the trunk at some point falls below the base of the pot like a tree growing from a    rock face and growing downwards under its own weight.

Semi-cascade- where the trunk extends horizontally from the pot like a tree growing from a rock face or bank of a river or lake.

In addition to these there are also some others, most of which are self-explanatory including Broom, Root over rock, Twin trunk, Group, Literati (where the branches are concentrated in the top third of the tree) and Saikai (a tray landscape with trees, other plants, rocks, sand and gravel).

There are several ways of obtaining plant material suitable for bonsai:-

Buying a ‘ready-made’ bonsai- quick but not cheap!

Collecting from the wild- most of the finest Japanese bonsai are collected, naturally dwarfed and gnarled trees due to their harsh growing conditions. However, they are not easy to find or to ‘lift’ successfully and the permission of the land owner is always required.

From garden centre stock- a good way to start out in bonsai as suitable plants are generally not expensive and can produce a recognisable bonsai fairly quickly. Bare root hedging is a good source of cheap plants especially for group plantings.

From seed or self-sown seedlings- inexpensive but very slow- it really depends how old you are!

From cuttings- quicker than from seed and a good method for group plantings.

Once suitable material has been found and some initial training carried out it is time to find a suitable container. Generally, at first ‘training’ pots are used which are much less expensive and deeper than ‘final’ pots. Most larger bonsai trees are in fact grown in the open ground for a few years in order to develop a more impressive trunk. Containers whether training or final must have quite large drainage holes (which are covered with fine, plastic mesh rather than crocks which take up too much room) and must be frost proof as most bonsai trees will spend their whole life outside in the open air. Indoor bonsai tend to be created from tropical or sub-tropical plants which are more suited to growing indoors. Most final pots are ceramic with the exterior glazed or unglazed and the interior unglazed so that the roots can ‘grip’ the pot and keep the tree stable. In terms of the choice of pot for a particular tree the size and shape of the pot should create a good balance with the height and spread of the tree and its colour and finish should be appropriate to the character of the tree.

As you can imagine there are a whole range of specialist tools available for pruning, grooming, shaping and repotting. However, in order to make a start some sharp scissors, a pair of secateurs, a kitchen fork and a pair of wire cutters will make up a basic set.

You will have realised by now that growing a tree in a relatively small, shallow pot over a number of years is not for the faint-hearted and demands a fairly high degree of maintenance work and commitment- just like raising children!

Watering correctly is probably the most important factor in the successful cultivation of bonsai. In shallow pots with large drainage holes soil can dry out very quickly and daily watering during spring, summer and autumn is usually necessary and is best done in the evening once the sun has become less strong. It is important to make sure that any water has penetrated into the soil/compost and not just run off the surface and a good way to do so is to water all the trees once and then give them all a second water a little later. Trees which are not fed may survive but they will not thrive partly because daily watering soon flushes out nutrients from the soil. Feeds come in two forms as for most potted plants- granular and liquid and most people use a combination starting with granular from April onwards and then changing to liquid from mid-summer to September. The liquid feeds need to be lower in nitrogen and higher in phosphorus and potassium to help root growth and to harden the twigs for the winter. Tomato food is a good choice as is any sort of seaweed fertiliser. A major task in the late winter and early spring as the buds begin to swell is to repot the trees. For deciduous trees this is usually from mid-February to the end of March and for evergreens is April. Repotting is carried out for two main reasons, firstly so that the roots can be pruned to encourage new feeder roots to form and secondly so that some of the old compost can be replaced by fresh compost. Smaller trees need to be re-potted every year, larger trees less often but the only real way to tell is to lift the tree out of the pot to look at the root mass. If it is filling the pot and winding around the inside then it needs re-potting! Basically, the old compost is gently raked away from the surface, the edges and base of the root ball are loosened by raking and excess root is cut off with a pair of sharp scissors which gives a space of an inch or two all the way round to be filled with new compost. The pot is then cleaned, the drainage holes re-covered and the tree replanted, usually in the same pot, using new compost which can be worked around the roots using a chopstick or pencil. Most bonsai enthusiasts have their own preferred mix of compost which can be varied slightly for different types of tree. Traditionally this has consisted of a mixture of loam soil such as in John Innes 2 or 3, an organic compost, grit and, if available, some leaf mould. Such mixtures give good drainage, allow the roots to breathe and can hold sufficient water and nutrients. However, a more modern approach is to use less, if any, actual soil, light and inert volcanic materials instead of grit, composted bark instead of compost plus a form of small clay granules known as Akadama. Maintenance pruning takes place throughout the growing season depending on the tree’s growth habit as well as at the time of re-potting. These techniques maintain or create the shape and form required and encourage branches and twigs to grow in the ‘right’ direction as well as preventing the top from growing too vigorously and the tree becoming top heavy. Such pruning is either done by the thumb and fore finger for soft growth or by scissors or special cutters for harder, woody growth. Wiring is a particularly important training technique as it allows the trunk, branches and twigs to be shaped in the required direction. The wire is ‘soft’ aluminium which is easily bent by the fingers and is coiled around the branch which can then be gently moved into the shape and position desired. It can only be done on wood which is still supple and after a few months the wire can be removed. Sometimes the trunk, branch or twig will then hold in place and, if not, new wire can be applied and the process repeated. Perhaps the most noticeable effect of wiring is to produce the down sweep of lower branches which immediately gives the impression of age even in a relatively young tree. The biggest danger of wiring is that it is left on too long and has begun to cut into the bark. This doesn’t kill the tree but it does scar it and although the scars will heal to some extent they don’t always disappear completely.

It is possible to grow almost any plant in a container but as a general rule the best bonsai subjects have naturally small leaves and fine, rather than course twigs, develop interesting trunks and bark with age and, if any, have naturally small flowers and fruits. Certain plants are also more suitable for certain styles, for example Cotoneasters make very good cascade and semi-cascade trees whereas Japanese Maples and Larches are mostly grown as formal or informal uprights. If you still want to grow trees but find the bonsai method a bit overwhelming you can, of course, just grow a small tree in a normal patio pot. It can still be shaped and pruned but will be much easier to care for and will happily live in a pot for several years.

Finally I will leave you with a list of suitable bonsai subjects:-

Deciduous:

• Japanese Maple (Acer palmatum)
• Trident Maple (Acer buergerianum)
• Birch (Betula)
• Hornbeam (Carpinus)
• Beech (Fagus)
• Japanese White Beech (F. crenata)
• Cotoneaster (some are also evergreen)
• Hawthorn (Crataegus)
• European Larch (Larix decidua)
• Japanese Larch (L. kaempferi)
• Crab Apple (Malus)
• Japanese Flowering Apricot (Prunus mame)
• Oak (Quercus robur)
• Chinese Elm (Ulmus parviflora)
• English Elm (U. procera)
• Wisteria

• Japanese Elm (Zelkova serrata)

Evergreen:

• Cedar (Cedrus)

• False Cypress (Chamaecyparis)

• Japanese Cedar (Cryptomeria)
• Japanese Holly (Ilex crenata)
• Chinese Juniper (Juniperus chinensis)
• Needle Juniper (J. rigida)
• Shrubby Honeysuckle (Lonicera nitida)
• Spruce (Picea)
• Mountain Pine (Pinus mugo)
• Japanese White Pine (P. parviflora)
• Scots Pine (P. sylvestris)
• Japanese Black Pine (P. thunbergii)
• Firethorn (Pyracantha)
• Azalea (Rhododendron)
• English Yew (Taxus baccata)
• Japanese Yew (T. cuspidata)

April's talk is on Saturday 6th but with two small changes from normal. It will be held in the Wild bird room which is next door to the Pet department and will start at 10am rather than 9-30am. Attendance is free as usual. Hope to see you there.

That’s all for this month but I will be back in May with ‘Preparing for the Summer’ including items on summer bedding, plants for shady places, taking leaf cuttings and creating standard Fuchsias. As always the blog will be on the website from the first of the month and the talk on the first Saturday which is May 4^th. Details can be found nearer the time on the Old Railway Line’s website under ‘events’. Also don’t forget that at the end of this month on Monday 29^th David Domoney will be at the Old Railway Line giving a talk and signing books. Full details are available on the website and I would encourage you to come if there are any tickets left. Until next time enjoy your gardens and have a wonderful April.

Keith.