The month where seedlings are growing fast, flowers appear more and more, and winter jackets can finally be put away. At least, I would like to think so but can they? There is a saying in Dutch: 'April doet wat ie wilt' which translates to April does what it wants, how true! Maybe do not put those winter jackets away just yet even when we have enjoyed lovely warm and sunny spring weather.

Jobs are quieting down in propagation but the pace is very much picking up when it comes to displays and production. Let's garden on!

1. Check monthly plan

A quick check over should do for April.

2. Check, take, and pot on cuttings

Dahlia and chrysanthemum cuttings should be ready to be potted on. At the end of April they should be ready to be moved to colder areas such as a cold frame for hardening off. Please see the April outdoors article for hardening off details. If plants are great for taking softwood cuttings, now is a good time to start taking those. For example, when half hardy plants are showing fresh new growth take softwood cuttings from them at this time. Softwood cuttings are taken from new growth that is flexible and soft and often is a light green colour. When taking cuttings keep a close eye on humidity levels. It is getting warmer which means water evaporates quicker which means we need to mist or water more regularly.

3. Select grape and fanned peach shoots, feed, and water

It is very satisfying to see new shoots growing on, for example, vines and peaches. Grapes grow on current year’s growth so select two strong new shoots per support and pull off the others. One will be the one we grow, the other one is a back-up. When one strong shoot can be tied into the support system, tie it in and monitor it for a few days. When the tied in shoot is happy and is growing strong then pull off the other one so the plant can fully focus its energy on one shoot. Grapes like consistent moisture, make sure to water them accordingly and please remember that moist does not mean wet. At this time start feeding them once every two weeks with a liquid fertiliser. When weather warms they will start growing quite quickly so keep on top of those shoots. Tie them in or twine them around wire support. Grow one or two bunches of grapes per shoot. Grapes take a lot of energy and water so if we would grow more than one, the size of grapes will be smaller than when growing one or two bunches. I like to grow one per shoot. Remove any other shoots and lateral shoots. Lateral shoots start growing at the base of each leaf and blocks light and restrict airflow. Tendrils can be great but they can also be a pain when we need to cut the stems off at the end of season. Remove any that are not wanted.

Let’s look at peaches. Peaches are growing quite a lot of shoots which will grow into new branches. If we would leave all these shoots, similar to grapes, they would block a lot of light and restrict airflow. This could lead to a great environment for pests and diseases and it restricts growth of the peaches. To avoid that, thin out the shoots for a healthy tree. Leave a strong shoot at the base of each branch and leave another one roughly 15cm away from the first one. Now we need to use our long term thinking.

Peaches grow on previous year’s growth. Look at the tree and leave any shoots where an empty space could be filled with that branch for the next season or where it could replace an old branch. Do not leave too many though because that means energy is going to lots of branches instead of juicy peaches. Do leave one at the top of each branch as it will help drawing sap upwards. In regard to thinning fruits it depends on the size. A peach roughly grows to the size of a fist. Use that size as a guide to thin out any fruit that would be in the way of one reaching its full size. This translates to three or four big and juicy peaches per branch.

Do not thin one tree at once but do it in stages to avoid the tree to stress. Thin one third of a tree every two or three days. I do not feed the peaches regularly. Once early in the season and once during their growth (May) I feed them with fish, blood, and bone which will last for quite a while. Depending on what you prefer to use, apply appropriately.

4. Pests and diseases management

From now on keep a good eye on what is going on in glasshouses and conservatories. Temperatures are rising which means more insects which also means more pests like aphids, whitefly, spider mite, scale, and mealybug. I spray soapy water once a week or once every two weeks on plants that suffer from pests. Biocontrol will start to arrive soon too. Grapes can suffer from diseases such as powdery mildew. Spray a soapy mix if comfortable with that and remove any leaves that are infected.

Weed! Weeds can carry diseases or attract pests so get rid of them when they appear. Ventilate areas to provide good airflow. Diseases and pests thrive when there is poor ventilation. Open those vents and doors when weather permits. Keep an eye on temperatures, they can drop quickly in the evening and at night so make sure to close vents and doors too.

5. Sow, plant, and harvest

April (and May) means planting tomatoes, cucumbers, peppers, and chillies and and and! I love it when I can fill up glasshouses with veg that do well indoors.

Sow and plant in a polytunnel too. Look up the spacings for seeds and plants to give them enough space to grow into healthy and tasty crops. Maybe you already started sowing or planting under protection and are harvesting salad crops, radishes, and strawberries. Yum!

6. Power wash

There is a pause in April between moving seedlings to the cold frame to harden off and starting to take softwood cuttings. In this pause it is a good idea to power wash the propagation area or any other area before creating displays. Plan for early in the morning on a warm day so the space dries quickly. Move any plants and tools out and if using gravel for display benches, collect it in buckets and clean it separately because power washing gravel is not a good idea. It would go everywhere! When everything is moved out, get a power washer or pressure washer ready and dress up in waterproofs and wellies. Goggles are needed to. Sexiness right there! A power washer heats up the water which is great for killing nasties but a pressure washer works well too. Open the doors and windows and go wild. Ohhh the satisfaction when green disappears from slabs, benches, and windows!

Be careful in glasshouses with cleaning glass. Do not go full blast up close because glass might end up breaking or you could get injured. It is a good idea to work with two people or to let someone know what you are doing so they can check in and make sure you are alright. Do take breaks and drink lots of water because working in waterproofs is not the most fun when it is warm. When you are done, squeegee excess water out and leave the doors and windows open in order for the space to dry out. All done? It is time for a tasty treat after all that work!

7. Refresh displays

When the space is clean let's get creative. In April more flowers are blooming. Take a look at the display and re-create it. Rearrange foliage plants with flowering ones, play with colours, and deadhead. Clean and tidy pots and benches. There is not much more satisfying as putting all the work in with attention to detail and stepping back when we are done. Admire the creations.

8. Water and feed

It is very important to keep plants watered to their liking. I cannot say this enough: know the plants ’needs! It is getting warmer so water will evaporate quicker and plants will transpire more, losing water through the leaves. Check them often. The weight of a pot can tell us a lot about how much water is in the growing media. There is no 'quick fix' or 'one rule fits all' when it comes to watering and it always annoys me when I hear people advice others to water their plants twice a week. Watering does not work like that, use eyes and touch knowing what the plant needs. There are many reasons why plants do not thrive indoors but I reckon incorrect watering is the number one reason why houseplants die. Treat plants as pets, they are living beings and have their own needs too. Research in order to care for them properly.

Start feeding plants. Plants in pots indoors do not get nutrients naturally, we need to provide them with it and again, know the plants. Some will need feed every week, some every two weeks, some might need it only once a month, some plants such as tomatoes need a high potassium feed, plants like orchids prefer less nutrients, and carnivorous do not like feed at all but thrive on rainwater. Know... YOUR... plants!

9. Damp down when glasshouses are warm and dry out quick

It can get toasty warm quick in glasshouses and conservatories and although plants like warmth, too hot can cause damage. Damping down means wetting the floor and sometimes walls and sometimes the plants with water. Water will evaporate when it is warm which increases humidity. Why should you do this? Plants need water but the warmer and dryer it gets, the quicker it evaporates, and the more (most!) plants will struggle. Again, this is not the case for all plants. Think of a desert and what grows there, those plants often prefer dry air. Damping down can still happen, an indoor environment is different than outdoors but in that case do not dampen down the plants and walls.

Dryness could encourage certain pests like spider mite on peaches so increasing humidity will help most plants and prevent certain pests to an extent. I start to damp down when temperatures inside are roughly between 18 and 24 degrees Celsius, but it does depend on the season and the weather how often and when I damp down. Do not damp down late afternoon if temperatures are cool in the evening because water will not have a chance to evaporate and just sits in the glasshouse becoming manky which could encourage fungi or algae. Damp down when it will evaporate. At the start of April it might be once a day in the morning when it is warm, at the end of April it might be twice a day. In the height of summer it might be every day and three times a day.

Please note: This post is written in the south of Scotland - UK. Adjust the month to your hardiness zone. If you have specific gardening questions, please do not hesitate to reach out.