The giant cowslip gets its name from its strikingly close resemblance to the ordinary cowslip of dry banks and old pasture, but by comparison it is a giant. While the wild Irish cowslip can reach about 30cm, the giant cowslip can grow to at least four times that tall and specimens approaching 2m have been grown.

These are closely related plants, both part of the primrose family, and for anybody who likes primroses, or any of that family, this is a plant to try.

The huge flowerheads are made up of about 40 individual flowers, pale lemon-yellow in colour and capable of filling part of the garden with a sweet scent on a calm summer evening – similar to hyacinths.

The flowers open in succession, giving a long flowering period of about two months.

There are also orange and brick-red shades, but the most usual colour (and the prettiest) is the yellow. The flower stalks that hold the individual flowers are covered with white mealy wax. This makes a lovely contrast with the yellow.

The flowers stand well clear of the rosette of leaves, another primrose family trait. The leaves are large, broad and relatively coarse, something like those of a dock-leaf and even more like those of horseradish – bright green and vigorous.

Of the garden primroses, the true primroses, polyanthuses, cowslips, Japanese primulas and candelabra primulas, the giant cowslip is the last to flower. It opens its flowers from late May to July, depending on the location and the conditions in which the plant is growing.

In milder gardens flowering happens earlier, later inland and later when slightly shaded. It is also called Himalayan cowslip because it originated in the Himalayan region in southern Tibet, where it grows happily by streamsides and in marshy places. Its botanical name is Primula florindae.

While it looks fine as a single plant, it is really at its best when grown as a sweep of plants. This is not usually possible in small gardens, but it might be more easily accommodated in a country garden. If there is an area of wet ground, even muddy, this plant is at home.

Start with a couple of plants and allow them to clump up, splitting them and expanding the colony. Or wait and let the plant self-sow, which they do readily in damp ground.

Unwanted seedlings are easily pulled up or moved to other suitable areas. It tolerates some light shade, but can become drawn and lanky if there is too much shade. Besides, the flowers look best when illuminated with sunshine.

Although the large leaves die down completely in winter, this is a very robust plant and well able to compete with weeds, covering the soil effectively. It needs very little attention, once it is planted in suitable conditions at the outset.

It likes plenty of humus in the soil to retain moisture and to feed the plants. It likes the same soil conditions as some other notable wet-ground plants, such as gunnera, darmera and skunk cabbage. Those three are all larger plants than the giant cowslip, at least their leaves are.

The darmera and skunk cabbage flower earlier and the cowslip can keep the show going afterwards, allowed to spread between and around the large-leaved plants.

Its colour is bright but not garish and does not look out of place in a country garden. It can be started from bought plants, or from seeds, sown in spring or summer, grown on to reasonable size and planted out in autumn or spring.

Courgettes and pumpkins

Courgettes, pumpkins and squash are best left for planting until the start of June because they are so soft and easily-damaged by cold weather. Last year, the plants turned yellow in a chilly spell at the start of June, before the wonderful summer began. They soon recovered in the warm weather, but if a good spell does not come soon after planting out they can be given a severe setback.

Harsh, windy weather is as bad as cold nights and strong winds can cause physical damage to plants, still soft from the greenhouse. If the plants have been set out, a low wind-breaker of mesh or bushy sticks can help. Also, an occasional feed of liquid fertilizer can help the plant until its roots get away from the pot and into the open soil. Time lost now reduces results later as the summer is short enough.

Flowers

If not already done, plant bedding plants, pots and other containers without delay. Watch for slug and snail damage immediately after planting and make sure to water every few days until growth is active. Use a hoe to knock out weed seedlings before they take hold in the weeks after planting.

Trees, shrubs and roses

If necessary to reduce size, prune shrubs that have gone out of flower. Check that recently-planted trees are securely staked and have not run short of water. They are not out of danger until they have made new growth at the branch tips. Spray roses against blackspot if the weather is wet.

Fruit, vegetables and herbs

Continue to sow vegetables, such as lettuce, radish, carrots, peas, French beans and parsley. Sow seeds of winter cabbage and cauliflower. Apple and pear trees will need spraying against apple scab. Strawberries are likely to need netting against bird damage.

Lawn

Lawns have been growing well, with lots of showers and sunny spells. Control weeds before they get too advanced. Mow the grass regularly during this period of rapid growth. It is essential to keep ahead of growth to have quality, dense, green grass without yellow leaves.

Greenhouse and house plants

Water all indoor plants regularly and feed every two weeks. Fuchsias, cannas, lantana and marguerites can be taken outside for the summer. Plant out tomatoes, cucumbers, chillies and aubergines. Pot up busy lizzies, begonias and petunias for display.