Returning to work after my holidays, I was surprised to see how much the garden had changed in just a few short weeks.

Although my desk had a large stack of post and bills awaiting me, and no fewer than 160 e-mails had arrived on the computer, the plants didn't seem to have missed me in the slightest.

Under the professional care of our two remaining gardeners (we are awaiting the arrival of a new member of staff in September) the plants have shed their early summer freshness and moved enthusiastically into high-summer mode.

I was especially pleased to be greeted by the flowering of the hydrangeas, and also the eucryphias.

Eucryphias are large shrubs or small trees, natives of Chile and Australia, whose large white flowers with yellow stamens are produced in great profusion each August.

These flowers are much loved by bees and hoverflies - often the bushes seem to be humming when the sun is shining on them.

In the herbaceous borders, half-hardy perennials and annuals are prolonging the flowering period of the true perennials.

My eye was caught by the intense green flowers of Nicotiana langsdorfii, an annual grown from seed given to me some years ago by the head gardener at Kingston Maurward in Dorset.

There are not many plants with truly green flowers, compared to other, brighter colours.

Some, such as green-flowered tulips and gladioli, are the result of plant breeders' experiments but others, like this Nicotiana, are naturally green.

Others that spring to mind are the lady's mantle, Alchemilla mollis, and Chrysosplenium davidianum, the Chinese relative of our own golden saxifrage, Chrysosplenium oppositifolium.

In the herb garden, both angelica and fennel have umbels of tiny, yellowish-green flowers, while in the spring borders both hellebores and euphorbias sport green flowers and/or bracts.

Molucella laevis or bells of Ireland is another annual with green flowers; it is readily available from seed companies, but despite sowing seeds several times I have never managed to grow it successfully - I must be doing something wrong!

Later in the year Thalictrum lucidum and Kniphofia ' Percy's pride' sport greenish yellow blooms that stand out oddly among the usual reds, blues and pinks of the summer flowers.

It would be fun to plant a whole border of these green flowering plants, perhaps mixing them with grasses and green foliage plants such as hostas and ferns.

It should have a cool, elegant feel to it, especially on hot summer days.