How do I plant a hanging basket that lasts all summer?

Baskets fail in July for two reasons and neither is the plants: the compost volume is too small, and the built-in fertiliser ran out in June. Everything below is aimed at those two problems, and the biggest single improvement available is simply a larger basket.

What you'll need

• A basket, 350mm diameter or larger
• Liner — solid, or a wool or coir liner
• A saucer or a cut circle of old compost bag
• Multipurpose compost
• Loam-based John Innes
• Slow-release fertiliser granules
• Plants
• Water-retaining granules (optional)

Step by step

1. Buy a bigger basket than looks right.A 300mm basket holds roughly half the compost of a 400mm one and dries out in half the time. Nothing else you do will compensate for a small basket, and this is the single most important decision.
2. Check what it will hang from.A planted, watered basket is heavy — a large one can be 15 to 20kg. The bracket must go into masonry with proper fixings, not into render or a fence panel, and the hook must take the weight when someone knocks it.
3. Choose the liner for water, not for looks.A solid plastic liner, or a wool or coir liner with a plastic circle inside it, dries far more slowly than an open moss or coir liner. Moss looks best and dries fastest.
4. Put a reservoir in the base.A plastic saucer, or a circle cut from an old compost bag, in the bottom of the liner. It stops water falling straight through and holds a small reserve the plants draw on through the day.
5. Mix the compost properly.About two parts multipurpose to one part loam-based John Innes. The loam holds water far better, releases it more evenly and rewets if it dries. Mix slow-release fertiliser granules through at the rate on the pack.
6. Sit the basket in a bucket while you plant it.It holds it steady at working height and stops it rolling around. This is a small thing that makes the job twice as easy.
7. Plant through the sides as well as the top.With a solid liner, cut cross-shaped slits and push young plants through from the inside, wrapping the rootball in a cone of paper or plastic to protect it as it goes through. Side planting is what makes a basket a ball of flowers rather than a bowl.
8. Plant it densely.Far closer than you would in the ground — a large basket takes eight to twelve plants. They will be competing, which is why the feeding regime matters, but a sparsely planted basket never looks right.
9. Leave a 25mm watering gap.Between the compost surface and the rim. A basket filled to the brim cannot be watered — everything runs over the side and the compost stays dry.
10. Grow it on somewhere sheltered first.If you plant up in April, keep it frost-free and sheltered until late May, or a fortnight after your last frost. In the south that is roughly mid to late May, in the Midlands and north into late May, and in Scotland or a frost pocket it can be early June.
11. Start liquid feeding at six weeks.Slow-release granules and the compost's own feed cover roughly the first six weeks. After that, a high-potash liquid feed once a week — the sort sold for tomatoes works well — is what keeps flowering going into September rather than stopping in July.
12. Deadhead regularly.Ten minutes a week. Once a plant sets seed it stops flowering, so removing spent flowers is what extends the display. Some modern varieties are self-cleaning and need less.
13. Hang it somewhere sensible.Out of the strongest wind and, if you can, where it gets morning sun rather than relentless afternoon sun. Wind takes more water out of a basket than sun does.

Tips

• One larger basket looks better and is a quarter of the work of two small ones.
• A pulley hanger, or a hook you can reach with a long-spout lance, decides whether it actually gets watered in August.
• Trailing plants at the edge, something upright in the middle, and a third of the plants through the sides is the reliable composition.

Common mistakes

• Using a small basket — There is no watering routine that compensates for too little compost. A large basket is the whole difference between a display and a chore.
• Filling with multipurpose alone — It dries quickly, is hard to rewet, and its feed is gone in six weeks. Loam in the mix changes the water behaviour completely.
• Never feeding after planting — This is why baskets look tired by mid-July. Weekly high-potash feed from six weeks is not optional in a container that crowded.
• Hanging it out in early May — One late frost destroys a basket of tender bedding. Wait until after the last frost for your area, which is later than people think in the north.

If it doesn't work

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