GrowingHQ

Garden plants

80 plants across six habits. A habit decides more about where a plant goes than its category does — what it needs built for it, how much room it will eventually take, and whether it is there in winter.

The garden in August

The whole of August

Next month: 2 more jobs open in September. See what changes

Why these six and not one long list

A shrub, a climber and a bulb raise completely different questions. A climber needs to know what it will hold on with before anything is planted, because a twiner on a flat trellis simply falls off. A tree needs an ultimate height, since that is the number the label leads with least and the one people live with longest. A bulb needs to say whether it survives the winter in the ground. None of those questions is meaningful for the other two, so they are asked on separate pages rather than averaged into one.

Start from the corner you are trying to fill

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When to plant, and why the answer is usually autumn

Trees, shrubs, climbers and bulbs all establish best when they go in during autumn, and the reason is the same for all of them.

Soil holds its heat for weeks after the air has lost it. That lag is the whole argument: a plant put in during autumn has stopped making leaves but has not stopped making roots, so it spends the next two months building the thing it will need next July. The same plant put in during spring comes into leaf before the cold soil below it can supply the water those leaves lose, which is why it has to be watered all summer and the autumn-planted one does not.

Why autumn is the planting season: soil stays warm after the air coolsTwo curves across twelve months. Air temperature rises from about 4 degrees in January to a peak around 17 in July, then falls back. Soil temperature follows the same shape but lags roughly a month behind: it is cooler than the air through the spring and warmer than the air through the autumn, peaking in August and still around 12 degrees in October. Two windows are marked. In the autumn window from September to November the soil is warmer than the air, so top growth has stopped while roots are still growing, and a plant put in then spends everything on roots. In the spring window from March to May the air is warmer than the soil, so leaves open and start losing water before the roots below them are working, which is why a spring-planted shrub needs watering all through its first summer.5°C10°C15°CJFMAMJJASONDsoilairSoil warmer than airtop dormant, roots growingAir warmer than soilleaves out, roots cold
Illustrative monthly means for lowland Britain — the shape and the lag are the point, not the figures, and both vary by site, soil and year.

Two groups qualify it. Anything tender or borderline is better planted in spring, so that it has a full season in the ground before its first winter, and the same goes for perennials on heavy wet soil — an echinacea lost over winter has usually rotted rather than frozen. Bulbs run to their own timetable: most go in from September, but tulips wait until November. The bulbs hub has the depths, and August in the garden has what is open now.

Or start from your conditions rather than from a habit

If you know the position and not the plant, the question is the other way round.

What can I grow? takes your light, soil, space and month and answers from the same catalogue these hubs are built from — including what it rules out and why, which is the half of the answer most plant finders leave off. The collections are the pre-computed version for the questions that come up most.