Everybody knows forget-me-nots: the pretty little flower of spring flower beds and there are some wild species with even smaller flowers that turn up as weeds, not always rooted out because they too are pretty. And there are others in the forget-me-not family, such as navelwort or omphalodes and brunnera, which have flowers of the same pale blue. But the giant forget-me-not is like an ordinary forget-me-not on steroids, bigger in every way. This larger size is fascinating to plant-lovers and the plant has found its way around the gardens of aficionados as a result.

The giant forget-me-not is also called Chatham Island forget-me-not as it comes from the Chatham Islands, off the coast of New Zealand, and occurs naturally only there. The fact that is comes from such a remote place has made this plant a curiosity, and its obvious links to the forget-me-not family makes it all the more interesting.

While it is like a forget-me not, it is bigger in all its parts. The leaves are large, not unlike those of hosta. They are broad, with deep veins and held upright. They are perfect for catching rainwater, channelling it down the deep fissures and then down the leaf stem to the roots. The glossy leaves are evergreen and look very well even when the plant is not in flower.

It has been threatened in its native habitat by grazing animals and by invasive marram grass, the grass that holds coastal sand dunes in place and vies with the forget-me-not for this role.

The flowers are like perfect forget-me-nots only twice as large, blue, often with a white edge and carried in a large rounded cluster on a stout stem. The heavy flower cluster may flop over to one side, and even on the ground, but this is natural and they are just as impressive lying down.

This plant is reported to be under threat in its native habitat. It grows at beaches, thriving in sand and gravel just above the high-water mark, where lots of seaweed is thrown up by storms. One of the tricks of growing this plant is to mulch every year with seaweed, and it is often seen in gardens furnished with a necklace of nourishing seaweed. While it grows by beaches under its natural conditions, in very free-draining sand, this plant does not like to be dry at the root, as the large leaves do not like to be stressed.

It likes that seeming contradiction: free-draining but moisture-retentive soil. Adding seaweed contributes organic material, and lots of growers of the plant provide plenty of compost.

The climate of the Chatham Islands is much more benign than here, being closer to the Equator, about the same as the south of France. So it is not surprising that the plant is not very hardy. It can be damaged by any significant frost and killed outright by hard frost. It is usually grown in a lightly shaded spot, the branches overhead reducing the danger of frost, but it can also be covered in winter with garden fleece, and many keen growers make sure to have a few plants in a greenhouse in case of losses. The flowers quite commonly set seeds, and these germinate readily when sown ripe and fresh.

While the Chatham Island forget-me-not is seldom seen for sale, it is often passed between gardeners as seedlings, partly as an insurance against future losses, partly to share this beautiful, unusual plant.

What to do with tulip bulbs?

There is a dilemma with tulips when they start to go over. They are mostly planted in good positions in either flowerbeds or in containers of some kind. And they look wonderful in these places, until the petals fall and then they are in the way of putting in summer plants. Unlike daffodils that are grown in grass or the edge of woodland, tulips are planted in prime spots and there just is not time to allow them to wither back and replenish the bulb for flowering next year. If they are in containers, water well and the following day, take them out. Find a place in a border in a sunny spot with good drainage, where there is space. They do not have to be straight. Plant some hardy geraniums to hide the foliage of tulips as they wither back. Retiring the bulbs is better than throwing them out!

This week

Fruit, vegetables and herbs

Do not delay in sowing sweet corn and runner beans in the greenhouse for planting out in four to six weeks’ time. Vegetable seed sowing can continue, especially of maincrop vegetables, such as carrots, broccoli and peas. It is time to sow French beans, as the soil warms up. Spray apple trees for scab if they had it before.

Trees, shrubs and roses

Roses will need regular spraying against rose blackspot of the leaves. It is essential to prevent infection of the new foliage. Only container-grown trees or shrubs should be planted now. It is now really too late for moving shrubs or young trees within the garden, except evergreens. Spring shrubs can be pruned at this time.

Lawn

If the grass is yellow or pale in colour and slow-growing, it would benefit greatly from some high-nitrogen fertiliser. It is a good time to sow a new lawn or over-sow a patchy old one. The best way to do this is to scarify the lawn with a machine, which can be hired, and then to sow and feed at the same time.

Flowers

Watch for slug and snail damage during these weeks. Plants are often attacked as they come through the soil. Bedding plants should be grown on strongly by regular watering and feeding. Begonias and dahlias can be potted up, or planted out towards the end of the month, and corms of gladiolus can be planted out now.

Greenhouse and house plants

All greenhouse plants should be fed on strongly now and watered well to make rapid growth early in the season. Check for pests. Overgrown house plants can be cut back,watered and fed until they show signs of new growth. Houseplants can be re-potted.