In the garden: The secret of a good gravel garden base

The aftermath of the heavy rain last week is a greening up the countryside, as trees are bursting into leaf, grass is in active growth, annual crops are germinating, and it is beginning to feel like summer is just around the corner.

This is the time of year that we crave on those long, dark, winter days and nights, and it is so uplifting to see new life all around us.

As the temperatures rise and seed sowing is well underway, a constant reminder of the ideal germination conditions is all around as we observe the weeds appearing what feels like overnight and growing at lightning speed!

Removing weeds and applying a thick layer of mulch this month will save so much work later in the season.

At this time of year, there is nothing like observing what appears in the gravel, nothing better than a good self seeder, and having an area of gravel adjacent to a bed or border provides the ideal seed tray for material to land and establish - granted, some candidates are more welcome than others!

The native primrose is a welcome sight and it certainly has increased in numbers since the spraying of herbicides has decreased - that is worth of note.

Honesty, aqueliga, foxglove, fennel, parsley are great self-seeders.

An area of undisturbed gravel is also a good seedbed for tree seedlings and natives such as birch, oak, alder and field maple, which will freely seed themselves, creating young new trees if allowed to do so.

This can be a useful way of cultivating young tree seedlings for transplanting elsewhere in the garden.

Field maple, Acer campestre, is a fine smaller-sized native tree in Ireland and I recently had the pleasure of digging up many fine seedlings from under the mother tree.

Interestingly the seeds had germinated in gravel which had Mypex beneath, and so the tap root had not penetrated through the Mypex. Instead, the roots had formed a fibrous mat across the surface which made transplanting the young trees an easier task.

It remains to be seen how successful they will be in adapting to their new location post-transplanting.

These seedlings are best transplanted when dormant and not in active growth, so make a note of any worthy specimens and transplant them next autumn.

They have a better chance when moved away from under the shade of the mother plant at the very least, and I will monitor their progress.

Another good reason to use gravel as a mulch on paths or areas of hard surfacing.

Gravel provides a more sustainable alternative to paving, Tarmac or concrete surfaces, which are non-permeable and create a lot of run-off when heavy rains occur, and this seems to becoming more normal with extremes of weather.

In these days of trying to do the best that we can for the environment, then sustainable urban drainage (S.U.D.s) is a big consideration and one that we can all consider when doing hard landscaping in our own gardens.

What is S.U.D.s?

It is any way that we can slow down the movement of run-off rainwater from where it falls to entering waterways so that the volume is lessened and slowed.

Gravel allows the gradual reabsorption of run-off water back into the water table and alleviates the volume of run-off entering waterways during extreme weather events.

Gravel does need to be laid down well, provided with an adequate base layer of hardcore underneath, particularly if being used for vehicular traffic as a lot of weight is involved.

On pathways, it can be said that gravel is less comfortable to walk on barefoot, for example, which we may be during warm summer evenings. The solution is simple, put some paving slabs to serve as stepping stones through the gravel and these will allow for barefoot adventures!

Gravel is a relatively cheap option when covering an area and it allows flexibility as regards planting as some pockets of topsoil can be incorporated beneath, which will enable planting of grasses or perennials to provide some relief and soften the effect of a large area.

Having pockets of planting will further enhance water absorption abilities of an area also.

The correct depth of gravel and the size of the chips is important and walk gravel is generally 10-20mm size, with a layer of 40-50mm deep providing the best walking experience.

If the gravel is too deep then it will be difficult to push a wheelbarrow over the surface, and as gardeners we know the importance of this activity.

It’s best to use materials native to the locality and so red sandstone would be the most cheaply available gravel type in my area, but depending on where you live, then different colours and types of gravel will be more readily available.

Plant of the Week

When considering what plants to include in a gravel garden, plants that like good drainage and full sun come to mind.

These types include a lot of Mediterranean plants and Salvia sclarea var turkistanica comes to mind. This is considered a short-lived perennial or biennial plant that often dies after flowering but will freely seed itself if not dead headed.

This has soft green hairy aromatic leaves and bears tall bracts of purple flowers. It gets to about 1m in height and a spread of about 0.5m.

It will grow best in full sun but tolerates a little shade also.

A great plant for pollinators as its flowers are nectar rich.

A good plant to include in the gravel garden, providing texture, colour, nectar and seeding freely.