Building a rockery is like building a world
Building a rockery can be real fun, if you know how
There’s nothing quite like a rockery. The stone and the flowers look so right, and they can be truly beautiful things. Rockeries look like hard work, and they can be. The trick is to make a “layer cake” of your rockery and reduce the heavy lifting.
You can make a micro rockery in a small part of a garden bed, or do a sort of artificial mountain range covering a square kilometre.
However you do it, there’s one basic rule for rockeries:
You must be able to easily and safely access all parts of the rockery.
Create some space or rocks which can be used as steps to get in and do any work that needs doing. This is particularly important in big rockeries. Make sure you have clear access to all areas, after planting. Do not plant anything in or around your access routes, if it’s able to grow to become an obstacle.
Building a rockery
You start with basics:
1. Clear the area for the rockery. Don’t worry about weeds, they’ll get buried.
2. Put thick sand and gravel underneath for drainage. This should be a solid mass, very stable. The depths should be about a foot at least. (This is a slightly purist approach, but the gravel also provides a footing for the weight of the rocks and keeps them supported, like a foundation.
3. Site strategically placed bigger rocks which will act as retaining walls, as well as forming the boundary of the rockery.
4. Smaller rocks in this support layer are laid as a bed to add depth and structure inside the boundary of the big rocks. This looks like the gravel layer, a good base for the rockery.
5. The first thick layer of soil goes on next, about another foot of it at least, which will be compressed by the weight of the next layers. This should be a mix of sand and good fibrous compost or soil mix, and needs to be watered in thoroughly, creating a soil structure around these first rocks.
6. You can place the next layer after you’re sure the first layer of soil and rocks have formed a good base with no gaps. (These structures can shrink if the soil isn’t well connected to the rocks, and rain will wash holes in them, breaking up the structure. Just add soil until you’re sure it’s OK.)
7. The next layer of stones is placed according to your design, with some feature rocks on the outside boundary, and more small rocks as a bed.
8. Another layer of soil, again thick, really pile it on, and again you work it in well with water. (Doing this at a time of year when you get regular rain is a good idea. It helps compact the rockery structure, and you’ll see any weak points instantly, so you won’t have to rebuild the whole rockery after a downpour.)
When your rockery is complete, add a good solid layer of bark mulch all over it before planting. This further protects against heavy rain, and provides sun protection for the soil.
Extremely important- Don't take risks with rocks
To move rocks, use a hand truck to move them and a secure ramp when you have to elevate them. Do not lift even medium sized rocks at all, let alone repeatedly, because you can hurt your back. You should use leverage at all times, not muscle power. Rocks are odd shapes, their balances vary when handling, so don’t wrestle with them, work with them.
Make absolutely sure all big rocks are stable, particularly if they’re on higher layers. The big rocks should be completely immobile. If they move, they’ll take a ton of soil with them. Use other rocks as keystones to keep them in place.
Nutrients and rockeries
Drainage, soil types, nutrients and plant types are all important in rockeries, particularly raised rockeries. You need plants which are able to take the temperature variations in the rocks in all seasons. Big, tough woody plants, roses, and even tiny alyssum will grow in these environments, but others won’t.
Research is required:
- What are the best, most reliable rockery plants in your area?
- How much space do they need?
- What about trees, and can their roots break up a rockery?
- What about understorey plants?
- How do conifers affect a rockery? (Very well, but pine needles also prevent growth of other plants, so you need to site them carefully.)
Don’t be too surprised if you wind up with a rockery which looks like a cross between a flower show and a forest, and spend more time there than in your home.
Also don’t be surprised if you find yourself hankering to create another rockery. It’s quite addictive.