Do you want a sea of colourful flowers and magnificent plants in your garden and on your balcony? We will show you which gardening jobs should be done in spring, what you need to bear in mind when repotting, how to prepare potted plants for the season and how to successfully plant them out.
Overwintered container plants will need some care before they can move outside from May: you will need to remove any pale winter shoots, prune the plants, then repot them and add fertiliser. This is to thin out the plant and remove any old, withered or crossing stems. Pruning can also help keep plants nicely shaped. The tool list for this task is simple: all you need is a pair of secateurs. If you are pruning back thick stems on large tub plants, you may also need heavy-duty pruning shears.
There is no specific season for pruning plants, but it should always be done before the main budding of new growth occurs – pruning young growth at a later stage will only rob the plant of its energy reserves. Container plants may produce weak, spindly shoots in winter. These long, tender, pale green or yellow shoots form when a plant doesn't get enough light, and they should always be removed. Any plants which overwinter in a conservatory or a cool, bright place are likely to grow shoots early in the season. You can thin these plants out until the end of February, but after this, they should be moved to a bright, warm location; otherwise, they will begin producing spindly growth again.
If you have plants that have overwintered in the dark, prepare them for spring by placing them in a bright position from the end of March. This gives the plants a chance to start growing before they are moved outside in May; if the plants are kept in the dark for too long, the flowering time will be delayed.
In addition to the spindly shoots we have already mentioned, you should also remove any old, withered or damaged branches. Be careful not to leave any stubs behind – you should cut the shoots directly at the main stem or a thicker side branch. Branch stubs will usually dry out and not sprout again.
Geraniums, fuchsia, leucanthemum and summer-flowering container plants will produce blooms on new growth and can be cut back more severely, to two to four buds or a branch length of 5-10 cm. This will make sure they remain compact and bushy. Oleander, on the other hand, produces blooms on shoots that are two or more years old, so take care if you want to prune yours because it has become too large.
We recommend pruning in stages, reducing the size of the whole plant over a couple of years. Patience is a virtue here, as otherwise, your oleander will have no flowers at all for at least a year. Important: If you have shrubs in planters that have got too large, don’t just crop them to a uniform height all over: either cut off whole branches or trim side branches by a third – this means the plants will retain their shape.
One simple rule to remember: the harder you prune them, the longer they’ll take to flower.
Plants in pots or planters will one day outgrow their accommodation and need to be moved to a larger container; learning how to repot a plant is simple. Older container plants may need to be potted up every two to three years depending on growth, while younger plants can need repotting every year. When the plant has become potbound – i.e. the root ball is compacted with root growth, and the roots have begun growing out of the drainage holes – it's time for a change!
The pot size is not the only issue, though: even if not yet potbound, all container plants require new soil regularly. This is because the growing medium in any container will become depleted, losing nutrients and stability over time so that it quickly turns sludgy when it rains. By adding fresh soil, you give the plant renewed nutrients and improve water retention so you need to water it less often. Balcony plants also need new soil every year, whether they have been overwintered or newly purchased.
As well as new soil, you will need pots or other containers for the plants, a garden trowel and slow-release fertiliser. A long knife may also be useful for plants in tubs, as it will help remove the root ball from the pot.
Newly purchased balcony plants can be potted into a new container immediately, though you should not move them outside permanently until mid-May, as there is still a risk of late frosts.
You can also repot overwintering balcony plants into fresh soil from mid to late April. It is best to do this as soon as you have taken them out of their winter storage location and pruned them. Afterwards, you can move the plants to a brighter location.
Selecting the right kind of soil depends entirely on how long the plants will stay in the pot. For annual plants, you can use a good own-brand, peat-free soil from a garden centre. If a plant is going to stay in its pot for longer, e.g. in large planters, we recommend you use a high-quality brand of container or potting compost. You can also use multi-purpose compost. You only need specialist soil if you will be planting multiple plants into one container. Citrus plants, hydrangeas or azaleas are exceptions, as they always need specialised acidic (or ericaceous) soil.
When selecting a suitable plant pot, make sure that it has a broad base and is no taller than it is wide; this means it cannot tip over easily. Adding gravel for drainage adds weight and makes the container even more stable. Clay and terracotta are classic choices for pots. They are heavy, but have many advantages: in sunny locations, they protect roots from the heat, while in the winter, they keep plants safe from frost. However, if you leave the pots outside over the winter, make sure they don't take in water, as this will mean the clay is no longer frost-proof and might crack in freezing conditions.
If you like the look of stone and terracotta but would prefer a less expensive option, there are many plastic pots available in similar designs. Plastic pots generally keep the soil moist for longer because the water can't evaporate through the sides. Don't forget to make sure that the pot has a drainage hole. Waterlogging hurts all plants.
Here is how to repot your garden plants:
The selection of young plants on offer in garden centres can't compare with the variety of options available as seeds. Seed packs are also much cheaper than plug plants. And there is one more advantage: if you are looking for more unusual plants, seeds are the right choice because many species you can get as seeds are simply not available as plants. You can find out all you need to know about sowing seeds here.
You will need: seeds, a wide ruler for levelling, a wide piece of wood for tamping, seed trays or small pots and sowing soil.
You should generally only use specialist seed compost, as this is low in nutrients and will make sure your seedlings are not sluggish – they will be forced to grow lots of roots to source the nutrients they need. The resulting root mass will see seedlings grow into strong plants in the right soil.
You will not need seed compost if sowing directly into the earth outside. Summer flowers, in particular, can be sown directly into beds from May onwards, eliminating the need to start them off in trays on your window sill. For root vegetables such as carrots, direct sowing is the only option, while other vegetables that need warmth to germinate must be started indoors (e.g. tomatoes or aubergines).
If you are planting seeds indoors, clean old seed trays with hot water since young plants are very sensitive. Fungi can damage and even kill seedlings.
How to sow seeds
The size of the seeds will determine whether they should be sown in individual pots or propagation trays. Large seeds can be sown into pots individually or in pairs to get a good start until they are planted out. Small seeds are sown in flat propagation trays, so they can grow in large numbers. Here’s how to do it: half-fill the tray with soil and press down gently with your fingers. Now fill the tray up completely so that the soil in the middle is heaped significantly above the rim. Then skim off the excess with a ruler. You should hold the ruler at a slight angle of about 45° while doing this – and be sure to slide it beyond the edge of the tray. This will automatically compress the soil. Finally, press down gently on the soil with a wide piece of wood so that it bulges slightly towards the edges of the tray. Now, scatter the seeds directly from the package, distributing evenly, and sift some soil over them. Tip: Mix tiny seeds such as begonia seeds with bird sand and spread the mixture across the tray using a tea strainer. As soon as you can grasp them firmly by the seed leaves, the seedlings from the tray should be pricked out into small pots before they can be planted outside. You should only prick out the strongest seedlings.
The best way to water seeds is with a watering can with a fine rose. Now, cover the seeds with a clear cover. If you don't have a propagator, you can use a plastic sheet or some plastic wrap. This keeps more moisture in with the seeds.
Seedlings often grow towards the light and can become crooked, but here’s a simple trick to get your seedlings growing straight: place seed trays into a cardboard box with one side open. Stick a piece of aluminium foil into the box so that the incoming light is reflected off it. Seedlings grown in a lightbox like this tend to be significantly stronger.