When the rain stops, this month will be a good time to plant most summer annuals and perennials, lawns from seeds, many vegetables, and most trees, shrubs, ground covers and vines. For tropical plants, however, it is better to wait until April or May as they will take off better when warmer.
Existing garden plants
Most ornamental trees, bushes, lawns, and ground covers will benefit from fertilisers this month. A granulated fertiliser high in nitrogen suits well. Water it in thoroughly unless you can apply it when rain is expected. Continue to feed winter-flowering container plants. If your plants were affected by frost, March is the time to cut off frost-damaged portions of trees, shrubs and vines as soon as new leaves start showing. For bougainvillea, wait for new growth to begin, cut back and follow up with fertiliser and water. It blooms on new wood, so spring pruning can give more summer bloom.Cacti, succulents and some native plants have little or no need for fertilisers, while camellias, begonias, ferns, fuchsias, orchids, roses, fruit trees and vegetables have different requirements.
Planting from scratch
March and October are the two busiest months of the year for planting. Spring planting is best from March through to mid-June. Aim for drought-resistant plants, but be sure to group plants according to their needs for water as well as sun/shade and soil type.
This is the first month to plant seeds or transplant warm-season annual and perennial flowers and to fill flower beds and pots with warm-season flowers.Cool-season flowers (e.g. calendulas, poppies, nemesia, pansies, snapdragons, stock) were best planted in the autumn; if planted now they will give only a short span of bloom as the heat finishes them off (the height of their season is April). Some newer varieties of small-flowering pansies, however, are more heat tolerant and may last a bit longer.
Good choices of young annuals to plant now from packs for colour in sunny spots most of the summer include ageratum, cosmos, marigolds, petunias, salvia, sweet alyssum, and verbena. For semi-shade consider begonias, coleus, fuchsias, impatiens and lobelia.
There is a large choice of annuals from seed to start now, including ageratum, anchusa, balsam, ornamental basil, calliopsis (Coreopsis tinctoria), coleus, cosmos, gazania, geranium, globe amaranth, Rudbeckia, hollyhock, impatiens, lobelia, marigold, morning glory (whose seeds must be nicked so they will sprout), salvia, sunflower, sweet alyssum, thunbergia, and verbena.
An equally wide variety of perennials can be put in now, including achillea, agapanthus, campanulas, carnations, marguerites, columbine, coreopsis, daylilies, delphiniums, dianthus, evergreen candytuft, geum, penstemon, perennial forget-me-nots, and statice. In addition, there are many ‘newer’ plants, such as the ornamental grasses.
The perennial garden
The traditional understanding of a perennial is one which lives more than two years on the same roots, dies back in winter, and comes back into growth in spring. The Algarve’s hot climate affects some perennials so that they may not grow at all again the next spring, or may turn into woody shrubs or even flower year-round. It is wise to monitor your perennials to see how they perform. Regular pruning may be needed. The expected eventual height of plants is important when planning and planting your bed.
Roses will need plenty of water so they can produce plenty of leaves and buds for April flowering. Continue to fertilise roses. You may find that a complete fertiliser specific to roses is better applied once a month than every six weeks. Check for aphids and other pests and diseases and take early action. If you want roses to bear only one large flower per stem, start to disbud them now by gently removing the secondary buds except for those designed to grow in bunches like the floribundas.
Continue to water them unless rainfall is sufficient. After blooming, cut off any flower pods and give them fertiliser, but let the leaves die back naturally rather than cutting them. Continue to plant gladioli, watch out for snails, feed potted gladioli with fertiliser; tie them to stakes as they grow. Start tuberous begonias in March. Check any tubers you retained from last year or buy new (best to buy those which already have a sprout or two as some begonias can be slow to start growing). They are not so easy to grow, but do best in acid rich soil in semi-shade.
Citrus and avocados
Plant trees this month with good drainage. Begin fertilizing them this month, watering it in deeply.
Start to prune now as flowers grow only on new wood. Young plants need little or no pruning, but after five years they should be pruned a little every month from March to August. First choose three or four woody branches on opposite sides and prune the whole branch back to three growth buds to encourage bushiness and re-growth. In four to six weeks remove another three or four old branches in the same way. Continue throughout the summer. Follow with fertiliser and water. Don’t prune hibiscus in winter.
A wide range of crops can be put in now, including artichokes, corn, green beans, some spinach, tomatoes, beets, carrots, radishes and turnips as well as the cool-season crops such as broccoli, cabbage, potatoes. In warmer gardens, cucumbers and some squash can be started. Wait, however, until April for the real heat lovers – aubergines, melons, peppers, and pumpkins. Plant for successive crops, planting each about three weeks apart to avoid gluts. Use a quarter or a third of a seed package at intervals of two to three weeks.Plant asparagus seeds now for a crop ready for harvest in three years.Make sure the vegetable area has deep, fertile soil with good drainage. Add plenty of organic compost to be sure, or create raised beds filled with soil and compost.
Vegetables need plenty of water, about an inch per week. The ideal irrigation system is a drip one which uses less water than watering furrows.Don’t forget herbs. Put in basil, marjoram, mint, oregano, parsley, rosemary, sage and thyme. You can intersperse herbs with vegetables or they can be put in their own bed or large pots. Rosemary is best not planted alongside other herbs as it grows large and woody, and mint is very invasive so is best contained; a pot of any size is ideal.
She does write: "Cacti, succulents and some native plants have little or no need for fertilisers," ... "Aim for drought-resistant plants, but be sure to group plants according to their needs for water as well as sun/shade and soil type."
Maybe the advice for zero water gardeners at the moment is "do nothing" - if not, Rosie Peddle from the Mediterranean Gardening Association Portugal can advise.