The common nasturtium, Tropaeolum majus, comes from tropical countries in South America, such as Peru and Columbia. It can take no frost at all and it is one of the first plants to be killed each autumn. Remarkably, it survived the winter in a few places close to a house wall. It grows rapidly between May and October, flowering generously and setting copious amounts of seed. The seeds are hardy and can survive frost because they have a corky layer that acts as insulation. Seeds can be sown from April, and usually sustain their presence for many years, even decades, by shedding.

The colours are mostly red and yellow, with a range of shades. Nasturtiums are ideal for a bank or the base of a hedge or simply to scramble out over a gravel area. They look great in a country garden because they look so natural and there are likely to be more odd corners where they can be started off. The Canary creeper, also an annual from South America, not the Canary Islands, has masses of slashed yellow flowers on a strongly climbing plant. It is a great summer filler on a fence.

While these two species are annuals, there are several perennial relatives. These form tubers from which the stems arise each year. The stems are damaged by frost but they grow back with such speed that they can make an impressive sight in flower. Easily the best known of the perennial nasturtiums is the flame creeper, or Scottish flame flower, Tropaeolum speciosum. This plant is from Chile and its Scottish connection is simply that it thrives in the cool summers of the milder areas of Scotland, as it does here. This plant can grow up through the lower branches of a tree or shrub, or on a hedge, and produces bright red flowers that are followed by blue berries. These can be sown to raise new plants and have the strange capacity to germinate without producing a shoot above the surface, but still emerge the following summer. It resents root disturbance and can be difficult to establish by lifting clumps of tubers.

Another species, Tropaeolum tuberosum, produces relatively large knobbly tubers about the size of a medium-sized carrot. These are used as food, called anu, in South America, in the same way as potatoes, which originated in the same regions. This is a vigorous grower, a climber or scrambler, with a mass of foliage and arching hooded flowers in orange with a yellow front. It looks very exotic. The tubers can be lifted and stored free of frost in cold areas, or covered with a few buckets of compost in milder parts.

A grayish blue-green species with patches of yellow flowers, Tropaeolum polyphyllum, is perennial with long tubers and it is unpredictable. It can pop up in different places each year, often more than a metre from its previous spot. It needs well-drained ground while the others like more humus, lots of leaf mould and good moisture retention in the soil, but never wet.

These tuber-forming perennial nasturtiums come from mountain areas of the countries of the Andes Mountains and while they originate in the tropics, the summer weather is relatively cool and not badly unlike an Irish summer.

Parsley seed can be slow to germinate and it is best to wait until late spring when the soil warms to sow it. If you have had trouble getting parsley to grow, try sowing it now. If it is sowed too early in the year when soil temperature levels are below its requirements, the seeds are likely to rot, or to germinate spasmodically with perhaps just a few seedlings here and there. When the soil is warmed up, from now on, parsley seeds will germinate much more reliably.

Another common reason for poor germination is that the seeds can be stale. Be sure to use fresh seeds, not old packets that are out of date. Seeds can be tested by sprinkling a few on damp tissue paper in a glass jar kept in a warm place indoors. If they germinate they are viable. Sow the seeds in fine, well-tilled soil in a sunny spot. A fairly light, not very fertile soil is ideal. If the soil is too rich, the plants grow very soft and the leaves tend to lack flavour.

Trees, shrubs and roses

Pot-grown trees and shrubs can still be planted. It is important to water new plants if the weather is dry and even then rain is often not enough. Check to see it the rootball is dry and water heavily. If susceptible, rose bushes should be sprayed to control blackspot disease.

Lawns

Grass growth was very slow earlier and lawns with low levels of nutrients have struggled to recover. Apply lawn feed or high-nitrogen fertiliser if necessary. Do not use too much but repeat after eight weeks if necessary. Sow new areas of lawn during fine weather.

Fruit, vegetables and herbs

Sow seeds and thin vegetable seedlings as they reach a suitable size and take out weed seedlings. Repeat sowings of salads can continue, and sow maincrop carrots, broccoli and peas. Sweetcorn and runner beans could still be sown.

Flowers

Watch for slug and snail damage during these weeks as plants are attacked as they come through the soil. Bedding plants should be regularly watered and given liquid feed to make good size. Space the plants well to give them room. Plant begonias, dahlias and gladiolus.

Greenhouse and house plants

Feed greenhouse plants each week and water well. Spray grapevines for mildew with a rose spray if it had the disease last year. Houseplants can be re-potted now, if they are pot-bound and inclined to topple over. Overgrown house plants can be cut back now and well watered.