Last time we discussed how to build a raised bed and which height would be best suited for your needs. So this time I would like to make a few suggestions about what to grow in it.
The beauty of having a raised bed is that the soil put into the bed can be better than you may have in your garden, here I am thinking cold wet clay can be changed for a much better open crumb structure.
For more details of the soil to place into the bed, please see here. With a raised bed you do not walk on it and so save soil compaction and the need for digging. If you need to be on top of the raised bed for picking soft fruit for example then I suggest placing a plank across the bed resting on the sides and then use that to get access to the plants.
Read on for suggestions on what to grow
Soft fruits: Such as strawberries, currants, raspberries and blackberries.
Vegetables: Almost any vegetable can be grown in raised beds.
Herbaceous perennials: Raised beds are a good idea for establishing a cutting garden for cut flowers.
Alpines: Ideal for alpines that relish good drainage. Also winter wet kills more alpines than any other factor, so a canopy can be placed over the bed in winter.
Small trees and shrubs: Depending on how big your beds are, you may be able to grow some smaller trees and shrubs, especially if the bed is placed on soil and the roots can down deeper than the raised bed depth.
Ericaceous or lime-hating plants: By filling beds with acid soil, lime-hating plants such as heathers and rhododendrons may be grown in areas of alkaline soil.
The soft fruit and vegetable growing is straight forward and here I will concentrate on the ornamentals. In horticulture the word ‘ornamental’ is used to cover any plant that is not edible. So what shall we plant, well treat the bed as you would any other bed in the garden. Use the same ideas and design techniques of adding odd numbers (3,5,7) of plants and using triangles to place the plants so that they intermingle and do not sit in rigid straight lines.
As the bed is raised you could treat it like one giant hanging basket with trailing plants at the edges to cascade down the sides and hide the retaining walls a bit. Against the far side put taller plants, remembering that if you can walk around the raised bed the taller plants need to be in the middle and lower height plants arranged around it. This means it will give a pleasing view no matter which side you are passing the raised bed on. Over this winter I have planted out a lovely trailing viola with deepish blue flowers called ‘Cascadia’ that so far has stood frosts down to -5 and is flowering its heart out. Here are some other suggestions:
Hardy annuals such as Alyssum, Calendula (pot marigold), Iberis (candytuft) and Limnanthes douglasii (poached egg plant) all stand frosty conditions without protection so in Spring can be sown directly in the space they are to occupy. Whilst half hardy annuals need to be raised indoors and then planted out after all chance of frost have passed, plants such as cosmos, nemesia, marigolds and tobacco plants. Next we have hardy biennials, in this group are Alcea (hollyhock), Dianthus (sweet William), Erysimum (wallflower) and Myosotis (forget-me-not). Ornamental brassicas (kale and cabbage) are ideal for winter displays.
For a focal point in your bed you could consider half hardy or tender sub-tropical plants such as Banana, Canna and Palms. I would suggest that these are grown in pots (so that they can be brought indoors in winter) and the pot sunk into the bed after all chance of frost has passed. Also hardy perennials or shrubs can also be used for a focal point or to create a backdrop for a raised bed that can be viewed from one side only. Such as Erica (winter-flowering heather) to extend the season of interest, euphorbia and heuchera can give valuable flower and foliage colour through the winter months as well as summer. Additionally, agave, dwarf conifers, cordylines, Phormium (New Zealand flax) and ornamental grasses can provide a central focus for the bed. Lastly do not forget bulbs and corms, you can have various bulbs flowering for nearly 11 months of the year and a small raised bed filled with bulbs can be eye catching. If in the past you planted up a pot with daffodils, tulips and crocus all in their correct depths in the same pot, then the same thing can be applied to the raised bed. For a Spring display try planting a mix of Allium, Anemone blanda, crocus, hyacinth, early-flowering Iris reticulata and tulips to brighten up an area after the winter.
Finally a suggestion for year round interest would include Daffodil for Spring flower, Delphiniums for Summer flower, Dahlias for Autumn flowering, Snowdrops and Snowflake are Winter flowering along with Hellebores. Asters in my opinion are good for Summer into Autumn seasonal flower. Your actual choice is endless.