GARDEN TIPS - 05/10/18

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Our Landscaping Team builds a lot of raised beds for customers, either using rendered, lined, painted and filled concrete blocks (often with lighting and integrated hardwood bench seating), poured concrete, or using railway sleepers. They can all look great and are the perfect way to add instant features. They also allow you to control the type of soil you have in various parts of your garden. This means you can have free draining soil for your herbs and Mediterranean plants, ericaceous (acid) for acid lovers like Rhododendron, Camellia and Azalea; and even a nutrient rich, moisture retentive planting environment for bog garden plants (we’d usually line the base and walls with pond liner for this, with just a few drainage holes). You can also control the spread of notoriously invasive (fast spreading) plants like mint and some bamboos.

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Our designer Jeremy has put together a few notes on designing and building your own raised beds using dip-treated softwood sleepers. Just a few things to think about that you might find useful. Here he is…..

Sleepers are a great way to achieve quick results, create an impact and clean up the lines in a garden. Most gardens locally aren’t that big, so it’s even more important to think about the design of the space in terms of three dimensions, not just the usual two. Think about heightas well as length and width. Apart from anything else, different levels of raised beds allow you to play with the usual hierarchy of plant sizes. Smaller plants, put into taller beds, can seemingly dominate taller plants in the ground lower down. They can also break up the mundane symmetry of a square or rectangular garden.


We don’t use reclaimed sleepers. They’re generally illegal for use in public parks and spaces, due to the tar and creosote that seeps from them. This is clearly a hazard, so we simply won’t use them in private gardens either. They’re a lot cheaper, but that’s why.

We tend to use either untreated new oak or dip-treated softwood. Oak works out a lot more expensive but, even untreated, will last for many years, silvering in colour as it ages. Oak is pretty heavy and more tricky to cut, screw and generally work with. Unless you know your way round a tool box, I’d suggest you avoid them.

Dip-treated softwood sleepers are a great solution. Easy to cut and work with and not too heavy to move around.


Whichever you go for, they’re usually 240cm long, 20cm wide and 10cm thick. This is important in terms of both design and practicality. Design your raised bed to be multiples and fractions of 240cm: 120cm x 80cm or 40cm x 180cm, for example. That way, not only will you have minimal waste when you’re finished, but from a design perspective, all of your beds will look ‘related’ to one another, not just a chaotic set of boxes!

The width and thickness of sleepers is something you can play with too. Setting them ‘vertically’ (standing on one of the 10cm faces) allows you to achieve height more cost-effectively. Once you have committed to this, you can then design your beds to be at uniformly differing heights (20cm, 40cm & 60cm from the ground, for example). Again, this will make the design relationships coherent, without it being immediately obvious why.

Something I try to do is incorporate informal seating into designs. A standard chair seat is around 40-44cm high, so by stacking two sleepers on top of each other, you can effectively create a place to sit, without the need for additional furniture. Occasionally I might be more deliberate with this, designing most of the bed walls to be built with the 10cm face horizontal, but where I want a decent width seat, I’ll design that wall to be constructed with the 20cm wide face horizontal. That way, you end up with a nice wide bench, or informal table. Again, this won’t necessarily be immediately obvious to guests, but once noticed, it is usually appreciated!

Bed Building

Softwood raised beds are pretty easy to cut and put together. Let’s take an example and see how it’d go together.

Say you want three raised beds in a corner of your garden. One to be 160cm x 60cm; one 80cm x 80cm; and the third 120cm x 60cm. Something like this

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The individual pieces need to lock together - in the same way that bricks are laid across their joins. This adds strength. See where the join lines are in the picture above. It’s a question of measuring, cutting and laying out all of the pieces BEFORE you start to fix them together. So the design above would look something like this as cut pieces:

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Actually screwing it all together is the easy part. I’d recommend 150mm Timberlok screws. They’re silicone coated so go straight in without the need to drill pilot holes (you’ll need an electric drill for this). Two at each join, spaced equally, will do it - like this:

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Once your beds are built, you may need to screw a few pieces of 47mm x 50mm pressure-treated timber into the corners inside the boxes, to connect the layers and make sure they won’t move. We usually sharpen one end of these and hammer them into the ground by 15-20cm. We also cut them so they don’t come right to the top of the beds - so they are hidden by the soil.

Line the inner bed walls with heavy duty black polythene - just staple it in. Then choose the plants you want, add the type of soil they need - and get planting!

The main thing is to have fun with it. If you have kids, think about making one small bed that they can have as ‘their own’. Maybe let them can decorate it any way they want - they can then learn where food comes from by growing a few fruit and vegetables (tomatoes are always a good one) and eating them straight from the plant. They love all that!

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Leaf Mulch

 If your garden has trees in or near it, it’s worth saving the leaves to make leaf mould, which is an excellent organic mulch for the garden. It is easy to make a pen; just mould chicken wire into a bin with a stake in each corner to give it structure. Rake up and pile the leaves in. They’ll rot down over the gardening year ready to spread on borders as mulch following winter/spring. You can tell when it’s ready - it will be well rotted, and crumbly.


Tender herbs like Basil, Coriander and Dill can’t handle frost, so it is best to pot them up and bring them under cover before any serious autumn chill hits. Mint and Parsley are usually frost hardy, but the winter will usually damage the leaves, making them not so good for culinary use, so consider getting these under cover too. If you don’t have a greenhouse, cold frame or conservatory, even bringing pots up against a wall of your home can often help. Even a well insulated home will still usually emit some collateral heat.

This is also a good time to replenish dried herbs in the kitchen. Oregano, Sage, Thyme and Rosemary are ideal for drying, although as hardy perennials they can be picked all year round. One method of drying herbs is to first blanch them for no more than a minute and then strip leaves from stalks, lay them out on a baking tray in the oven on the lowest possible setting, with the door open a little to allow moisture to escape. Leave it like this until the herbs are dry enough to crumble between your fingers, let them cool down completely before storing.

Cutting Back

Now’s the time to clear up the garden and one key decision is which plants to cut back? Those with very unsightly faded leaves, such as Delphiniums and Geraniums, are best cut back. Others may have ornamental seed heads - Poppies, Allium, Grasses, etc. - so these may be better left in the border for now.

The following should be cut right back to ground level: Peonies, Leucanthemum, Nepeta (Cat Mint) Delphinium, Hardy Geraniums and Phlox.

Slightly less hardy perennials like Penstemons are best left un-pruned - the top growth provides some winter protection. Cut this back in Spring instead.

Spring Bulbs

The sooner you plant your spring bulbs now the better. The soil is still warm, so bulb roots get chance to establish before the weather closes in. This will help them fight wet and rot. That said, tulips are happy to go in as late as the end of November, so leave them until last if you want. 

Winter Bedding

Now’s also the time to plant winter bedding and baskets. The garden centres (including ours!) are full of pansies and violas. You get them home looking lovely, but often after a short while they seem to sulk - sometimes for the rest of the winter!

This is usually because they’ve had a near ideal upbringing in a temperature-controlled poly tunnel. When we buy them, they’re uprooted and plonked outside in the cold wet chill, without a chance to get used to their new environment.

It’s best to plant them earlier (around now) into the container in which they are going to spend the winter, and then place the container under glass/in the greenhouse or in a sheltered spot for a week or two, to give them chance to get established and put their roots down. By introducing the plants gradually to the cold reality of life outside, you’ll be giving them the best chance to flower through the winter.

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Prune Roses

From now until early winter is the time to prune roses, especially climbing roses, which need  a general prune, reducing size by about a third to prevent ‘wind rock’. Wind rock is caused by the long stems of the roses being caught by the wind which makes the plant rock, which in turn loosens its footing and roots. Over time the entry point of the trunk into the soil widens, allowing water and ice in, which will damage the plant and its roots. By reducing the top growth there is less for the wind to catch. 


Autumn is a good time to work on the lawn. It’s still warm enough to repair a patch by raking up the soil, covering with compost and grass seed. The lawn can be raked to remove thatch (dead and loose grass), spiked with a fork every 20cm or so, to ease compaction and improve drainage; and given an autumn feed - especially if yours got lots of wear in the summer (we’re thinking kids, games, football here).  If you laid anew lawn in the past six months, don’t feed it until next Spring - the new turf contains all the nutrients needed for now - if you feed it you may actually damage the plants.

If all that sounds too much like hard work, just do one thing: rake up and remove any autumn leaves. If they’re left covering any grass it may well kill the lawn underneath, leaving unsightly yellow/brown patches (grass needs a constant source of light, water and nutrient - the leaves deny it at least two of these!). 

Protect Your Plants

If you invested in any tender plants this year (plants that can’t handle extreme cold without a little TLC), they may need wrapping in gardening fleece before any frost arrives. Other suitable materials include hessian, loft insulation, straw, old blankets etc.  Bubble wrap is often advocated as a useful material for protecting plants, but you risk ending up with a well-protected and warm heap of mush. It is critical that air circulation can continue, which is why plastic in any form is a no-no. 

Some other plants need a layer of mulch (protective organic stuff like bark chips, leaf mould or compost  - ‘organic matter’ as some would have it) spreading around them. This applies largely to things like Cannas, Gingers and some ferns and herbaceous perennials that are planted in the ground and stay there year round. A layer of mulch will help to insulate the crowns of these plants against frost penetration. Spread it around your beds and borders anything up to 10cm deep  (anything is better than nothing!).  This can then be left to gradually incorporate into the soil due to weathering and worm action. It’s good stuff. Not only will it protect your plants, it will improve the soil for next year too.

Larger plants like tree ferns, palms and hardy bananas will all benefit from having a deep layer of mulch spread around their stems too and, in fact, a 5cm mulch of fresh compost all around your borders is a great idea generally (a trial was completed recently where one vegetable plot had compost dug into it before planting. In another the compost was just spread on top. Almost all vegetables produced were of a more uniform shape and better sized, grown in the latter. So sometimes doing less in the garden really does achieve more (not always unfortunately).

Have a great weekend.

The Lancasters Team