May is your last month to plan and prepare your garden and beautiful landscape for the potentially cold and harsh winter months coming up. The more preparation and work you put in, the more successful your garden will be at not only surviving, but flourishing in the winter months. This means it will be well prepared for new spring growth when winter passes.

Our may post covers pertinent topics like general garden maintenance, May garden woes, propagation tasks, planting bulbs, what to plant in May for colour and plants which feed birds in winter as well as what to do and plant in your food garden.

This blog is orientated around Western Cape gardening and landscaping but can also be used to a certain extent for other regions.

General maintenance in your garden

Being autumn there are going to be many leaves falling from trees and shrubs. Collect these and either add them to your compost heap now or keep them in black bags and then add them to your compost heap in spring when the weather warms again. In our February blog we spoke about mulching in order to keep the soil cooler and prevent water evaporating too quickly. Now at this time of the year we recommend mulching for the opposite reason. To keep the soil and roots of plants warm during cooler months. Please revisit our blog on February gardening to get more ideas on mulching. If you have not pruned your hedges yet then now is good time to do that before we go into the cooler months. Only prune evergreens and those shrubs which finished flowering in summer. Always prune your shrub narrower at top than at the bottom in order for sunlight to reach all parts of the plant to aid photosynthesis.

This will result in dense new growth right from the top to the bottom. Read our February blog for more advice on pruning. Prepare trees and shrubs you intend on moving in winter by cutting through the roots on two sides. Cut through the remaining two sides next month. Feed your bedding plants once every two weeks with a liquid feed or once monthly with a granular food like 3:1:5. If you planted sweet peas in March as recommended then feed these as well. If you have recently planted annuals, pinch out the first flowers to promote a generally better plant as well as improved blooming.

As the rainy weather starts weeds will become more prolific in gardens and grass areas. Be on top of weeding and remember to use flowers, leaves and roots as per our recommendations in our previous Facebook War on weeds and eat your weeds posts. In our winter rainfall gardens the height for lawnmower blades should be lowered slightly as our grass should spike in growth (N.B Kikuyu). If you haven’t already fed your lawn recently, then do so now before winter is upon us. 3:1:5 can have great results on lawn. The reason we have recommended a fertiliser not too high in Nitrogen is to encourage grass to have a strong root system to survive winter. If your lawn is very compacted then spike it with a garden fork or a spiker and sprinkle superphosphate, watering it into the holes afterwards.

Autumn foliage to collect for composting

Autumn foliage to collect for composting

May garden woes                                                                                                                             

In our March blog we spoke about identifying and treating Italian cypress aphid. These pests are particularly active during cooler months so we would definitely recommend continuing spraying for this aphid if your conifers have been affected by this problem. Please read our garden woes section of our March blog for more info on this.

At this time of the year breeding of rose beetles and fruit flies can be quite prevalent. Clear away fallen leaves and rotten fruit under fruit trees to prevent breeding and overwintering of the above mentioned bugs. Also if you have your own compost heap turn it once in a while to check for larvae and pupae of fruit flies and beetles. Do not overturn the compost as you will lose much needed heat required to break down organic matter into compost. Please see our Facebook post on how to control beetles. Fruit flies can be controlled by using fruit fly bait.

Snails will be looking for places to over winter at this time of the year. Clean up under containers and clumps of perennials and also clean evergreen shrubs at the base to prevent them from becoming hiding places for snails and other creatures and critters. Mulches made from rooibos work well to prevent snails, as well as adding crushed eggshells to beds is also affective. Please also see our Facebook post on how to control snails in your garden.

Also keep a look out for and treat roses for funguses like downy mildew, powdery mildew and black spot which can be prevalent during moister months of the year. Choose a fungicide which is listed for the particular fungus you are experiencing. Please also see our Facebook post on natural fungicides.

Rose beetles

Fruit flies on citrus

Propagation tasks for May:

This is a very important time of the year when it comes to certain propagating in the garden.  Hardwood cuttings, semi-hardwood cuttings of sub shrubs, splitting of overcrowded groundcovers and division of herbaceous perennials and bulbous plants are all forms of propagation which should take place at this time of the year. 

  • This is a great time of the year to take hardwood cuttings of shrubs, climbers and trees. Some examples of shrubs to take hardwood cuttings of are hibiscus, abelia, hydrangeas as well as deciduous plants and tree cuttings. Hardwood cuttings are taken from mature, firm woody stems at about 10-15cm lengths. They are taken in late autumn through to early winter. They are the slowest to root taking up to a year (they first need to form a callus), but worth the wait as the result is strong, more mature plants. When taking the cuttings, make sure that the top of the cutting is slanted so that you can identify top from bottom as planting upside down will obviously lead to failure of propagation. The cuts must be clean, precise and not ripped otherwise rooting will occur rather than propagation. The cuttings mix should consist of two thirds coarse sand and one third fine compost or loam. Take cuttings that are close to pencil-thickness from current season’s growth. It will be mature and woody, not soft and green. Cut off any unripened green growth at the tips. Try to take cuttings where the current season’s wood (1 year old wood) joins the two year old wood. The base of the stem at this junction has the greatest potential for root development; it contains a large number of dormant buds that supply hormones required for developing roots. The base of the cutting should be just below a bud and the tip of the cutting should be done just above a bud and sloped (to identify and for water to run off).
  • This a good time of the year to take semi-hard wood cuttings of sub-shrubs that might degenerate during winter months as well as older specimens that may be coming to the end of their lifespans. These should root readily before winter but if not mini hothouse situations can be created with coke and other bottles. These cuttings can overwinter and will be ready for planting in spring and summer. Rooting usually takes about 3-6 weeks but this may vary. Most sub shrubs tend to have a short lifespan and need to be replaced. Again like hardwood cuttings when taking the cuttings the cuts must be clean, precise and not ripped otherwise rooting will occur rather than propagation. Choose to take cuttings from healthy plants and cut pieces with healthy foliage. The cutting should be about 80-120mm long. It should be taken 2-5mm below a healthy node or bud. The top of the cutting must have 2-5 leaves which must be cut in half. The rest of the leaves below these can be nipped off at the stem neatly and tidily. The mix used to plant these cuttings in can be the same as the hardwood mix but the fine compost can be replaced with cocopeat or other peat in order for it to retain a little more moisture. Cuttings in general (hardwood and semi-hardwood) must be dipped in rooting hormone to encourage good rooting, rooting hormone number 3 should be used for hardwood cuttings and number 2 should be used for semi-hardwoods. Natural alternatives are cinnamon powder and a honey and water solution. Some plants which we would recommend taking semi-hardwood cuttings of are angelonia, Felicia, gaura, lavandula, osteospermum, pelargonium, rosemary, plectranthus etc.
  • Many perennial plants complete their blooming season in autumn or early winter and have to be cut down to almost ground level. This is when you can take some cuttings from these offcuts. These plants will then emerge with new growth in spring.
  • This is a great time of the year to still divide clumps of rhizomatous and bulbous clump forming plants for example watsonia’s, agapanthus, wild garlic and dietes. For advise on this, please reference our previous blog on March gardening.
  • Remember to continue harvesting seeds from herbs, veggies, flowers etc for propagating next season. Please see our Facebook post which gives you advice on how to collect seeds etc.

Hardwood cuttings

Semi – Harwood cuttings

Planting bulbs & general maintenance of bulbous plants:

In our March blog we discussed getting your garden beds etc ready for bulb planting done in cooler weather. Well our weather has officially cooled down so now is the time to do your bulb planting for winter and spring flowering as well as some summer bloomers which take a little longer to grow. If you haven’t already prepared your soil prepare adding compost, bone meal or other fertilisers of your liking.

Below are some tips for planting bulbs:

*Commonly not all plant’s labelled bulbs are actually bulbs, but some are rather corms and rhizomes for example.

*To get the bests results out of bulbs we would usually recommend planting them in bold groups of the same type.

*Before choosing a place to plant your bulbs remember that spring bulbs need to be cool, so don’t plant them next to hard landscaping, like driveways or paved pathways. Avoid north-facing walls, and if planted in containers keep them in in morning sun and afternoon shade.

*Plant all spring flowering bulbs with the pointed side facing up, except for anemones. Bulbs which have finger or claws like ranunculus should be planted with fingers pointed downwards. The planting depth of a bulb is dependent on the size of the bulb. Smaller bulbs like leucojums, lachenalia’s and tritonia’s should be planted 5cm deep and larger bulbs like freesia’s and irises should be planted about 10cm deep.

*When planting use a dibber or bulb planter to make the appropriate holes for the bulbs.

*The most important thing to remember when plating bulbs is that they must not dry out at root level. Soak the soil to a depth of about 15cm every 4-5 days. Remember that potted bulbs may need more watering.

Planting of bulbs

What to do and plant in your veggie & food garden in May:

If you have grown pumpkins and other squash then mature fruits should be picked. The fruit should sound hollow when knocked. If you have experienced problems with fruit fly then next season try covering fruit with paper or fabric bags tide on gently to prevent fruit flies from stinging fruit. Remove all flowers and undeveloped fruit from summer vegetables to speed up the ripening process of almost-ripe fruit and to also encourage plants to maybe pop out a little more fruits for you. You need to water well to encourage this but please note that this must be done in mornings as plants do not want to go to bed with wet feet. Tomatoes may need to be sprayed with fungicide to treat and prevent blight. Please also see our Facebook post on using aspirins to prevent blight and other tomato problems. Feed all veggies to strengthen them before winter comes. This is important particularly for brassicas like cabbages, broccoli’s and cauliflower. Baby greens and microgreens are especially fashionable and a way to grow these that will not cost you much money is to use your vegetable tops instead of throwing them away. Vegetables like turnips, beetroot, radishes and carrots can all be grown in shallow trays filled with water on a windowsill. You can harvest the small leaves for a while as baby greens and then this can later be planted into the ground as root crop again. If you have sweet potatoes growing, then now is the time to harvest them. This is the time of the year to divide chives and garden chives. If your veggie garden is currently in quite a lot of shade a lot of veggies can be grown in other parts of your garden between other plants as long as they are not being sprayed with poisons.

In regards to fruiting plants, ripening citrus should be picked, as well as the last apples and pears. Citrus trees actually require regular feeding and should be fertilised four times a year so if you have not already fed them then give them one good feeding before winter. Mid-autumn is a great time of the year to plant fruit trees as well as repot fruit trees in containers to ensure that they are settled for new spring growth. In our March blog we spoke about preparing your garden for strawberry planting. If your patch is not prepared yet, then prepare with ample compost and bone meal. Plant runners from mother plants or plant new young plants. Strawberries also do extremely well planted in hanging baskets and retaining blocks. In June and July deciduous fruit trees need to be pruned if you are planning on doing this. Start planning for this, as there is a science to pruning fruiting trees and if you do it incorrectly it can effect fruiting of the trees as well as lead to crop failures.

Examples of vegetables which can be sown and planted in May are broad beans, beetroot, cabbage, cauliflower, broccoli, celery, leeks, lettuce, onions, parsnip, garden peas, radish, swiss chard, oriental veggies, mustard, kale, kohlrabi. This also the last month we would recommend for carrot sowing before spring planting again.

General winter veg (Garden peas, onions etc)

Purple Cauliflower

What to plant in your garden in May:

May is the time of the year where you start planting for winter. We will discuss annuals to plant in May, indigenous perennials for colour, plants for autumn colour and what to plant for feeding the birds in your garden in winter.

For annual colour continue planting Bellis perennis, bokbaaivygies, Namaqualand daisies, nemesias, calendulas, dianthus and snapdragons. You can start planting violas, pansies and phlox in sun and semi shade and start planting Primula malacoides and vulgaris as well as Cineraria cruentus in shadier spots for annual colour. All of the above mentioned annuals and biannuals come in many different colours.

Pentas lanceolata, Barleria obtusa and other Barlerias, Euryops pectinatus and Osteospermums will provide you with sub shrub colour. Arctotis and Diascias will provide you with groundcover colour. Pentas lanceolata has masses of star shaped small flowers in clusters in a range of different colours. It is an indigenous hybrid and is actually very hardy. The flowers attract butterflies.

Euryops pectinatus is small shrub with bright yellow daisy flowers in mass. Again this plant is indigenous and extremely hardy.

Osteospermums sport masses of large brightly coloured daisies in many colours.

Barleria’s are another indigenous stunner with masses of either light blue, pink, salmon or purple flowers depending on variety. They are also very hardy, water wise and are versatile in the way that they can be grown in semi shaded conditions as well as sunny.

Arctotis ‘Red Flame’

Osteospermum hybrid

Nandina domestica (Domestic bamboo) is a tall but slim shrub with foliage which turns a lovely reddish colour in winter. It is a great shrub for small spaces and attracts birds with its red berries.

Please note that this also comes in a miniature which is great for borders and has extremely colourful foliage. It is named Nandina domestica ‘Pygmea’. In modern times many different colour varieties have come onto the nursery market.

Crassula capitella ‘Campsfire’ (or thyrsifolia even) is a groundcover with lime green and bright salmon red succulent leaves. It gets spikes with small white flowers which attract butterflies.

Different colour Phormiums (Flaxes) will also provide foliage colour for your autumn and winter garden. Mixing some of the red, purple, pink and yellow / lime varieties can really make quite a statement in your garden.

Nandina domestica

Winter can be kind of tough on birds when it comes to finding food sources. Make sure you introduce plants to your garden that will feed your birds which you love so much. Grasses like Aristida junciformus, Eragostris capensis and curvula and Melinis nerviglumus are all indigenous grasses which will provide food for seed eating birds. Shrubs like Leonotis leonorus (Wild Dagga) and Tecoma capensis (Cape Honeysuckle) will provide sunbirds and other birds with nectar. Aloes are also favoured by sunbirds and other birds and bloom in winter normally. Also plant what you know will attract insects which the birds will eat.

Aloe ferox

Garden with Aristida junciformis

As discussed in the March blog, this is still the best time of the year for planting fynbos and you will actually find blooming specimens at your local nursery, just waiting to be purchased to add hardy colour to your garden.

Protea compacta

Leucospermum Lipstick

In conclusion May is an extremely busy time in the garden and the more effort you put in the more rewards you will reap. Our hope is that this May blog has inspired you to be busy like a bee in your garden and enjoy this cooler month to get all your winter prep done.


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