Which flower plant can take long dry spells and still have flowers? The answer depends on one thing

For your exact brief, the strongest picks are lavender, nepeta, hardy shrubby or perennial salvias, sedum and achillea. All cope well with full sun and dry periods once established, and all still give you proper flowers rather than just surviving.

Best first choices

• Lavender: excellent for hot, dry, sunny spots and flowers well if the soil drains freely.
• Nepeta: long flowering, soft habit, very forgiving in sun and dry ground.
• Salvia: one of the best for repeat colour through summer in a warm, open position.
• Sedum: especially useful if the ground gets really dry; flowers later and is very tough.
• Achillea: reliable in poor, sunny soil and handles drought better than many border plants.

The deciding factor is not really the flower, but the drainage. In UK gardens, many so-called drought-tolerant plants fail more from winter wet than from summer dryness. If your soil is heavy or stays wet, sedum and achillea are usually safer than lavender unless you improve drainage or plant on a slight mound.

Because it is late August, you can still plant now if the ground is workable, but do not put small plants into baked-dry soil and leave them to fend for themselves. Water them in properly for the first few weeks so they establish roots; after that, they become much more drought-tolerant. If you want one simple answer, choose lavender for free-draining soil, or nepeta if you want the easiest long-flowering perennial for a sunny border.