Drip Irrigation – How Many Separate Taps Should You Install for Maximum Water Conservation?

The number of separate taps needed for drip irrigating the garden plants is a matter of pressure and efficient water management. In parks and large gardens, the irrigation designer will have calculated the diameter of pipe required and the number of separate stations that are needed, so that the all the drippers emit water properly.

In small gardens however, the gardener can often judge these things by sight, and simply divide the area into a couple of stations; say a line for the front garden, and one for the plants in the back. This might be enough as far as pressure is concerned, but hardly adequate in terms of managing water as efficiently as possible.

The factor, other than pressure calculations, that should determine the number of taps is the type of plants that make up the garden. The first rule of water conserving gardening is to estimate the annual water consumption of the different plant groups. The second rule is to plant these groups separately, so that thirsty plants like annuals or citrus trees are not next to drought-resistant plants. The third rule, obviously, is to install a separate irrigation line for each plant group, so that an independent watering regime can be applied to each one.

The important thing to remember is that plants differ not only in the quantities of water they need, but also in the frequency of the watering. To take two extreme examples; annual flowers might require watering every three days in the summer, while many drought-tolerant shrubs and bushes, are not only able to survive on a once-a-month-schedule, but actually suffer from over frequent irrigating.

Many of the irrigation controllers available to the private garden market consider this, by having three programs that allow for three separate watering schedules. Effectively, this provides for one schedule for the lawns, one for trees and shrubs, and another for flowers. It appears reasonable at first sight, because even if the lawn irrigation (for example) requires dividing into two or more stations to ensure sufficient working pressure, the watering frequency should be the same for all the stations. Such a configuration is insufficient however, for the purpose of optimal water management, and saving as much water as possible.

Let’s look at the question in a bit more detail, by seeing how the drip irrigation could be organized in a typical dry climate garden.

*The garden has a small lawn, irrigated by sprinklers on their own tap.

*There are two types of woody plants. Most are drought-tolerant shrubs and trees, such as Melaleuca, Grevillea, Juniper, Olive, Pomegranate, and Leocophyllum. We have determined that they need water to the extent of 200 liters per square meter a year, spaced out over 3-4 waterings during the summer. They will have a separate tap.

*The second group of woody plants is comprised of sub-tropical ornamentals such as Jacaranda, Duranta, Plumeria, Orange, and Lemon trees. They will need 400mm a year, being irrigated every three weeks through the summer. Do you not agree that a tap independent of the dry plants would be preferable?

*We can now divide the herbaceous plants into the modest consumers like ornamental grasses, Agapanthus and Liriope, and the water guzzling summer annuals. The former may need 400-500mm a year, on a weekly schedule, while the annuals would need 1,000 mm, on a schedule of every three days. A separate tap for each? I think so.

*The garden also has decorative pots and containers on the balcony and patio. These are planted with flowers and need watering every day in the hot, dry months. Ideally, the container plants should have their own watering schedule. They can be grown on the same regime as annual flowers, if these are in light, sandy soil. However, if the annuals are growing in heavy clay soil, the interval between each watering should be extended to permit sufficient oxygen in the root zone. As the pot plants may need water every day, it is not difficult to see why they need a separate tap for themselves.

In this imaginary but representative case, it is clear that a three-program controller does not offer enough options for optimal water use. It is for this reason that you should be looking for a timer that allows for each tap to be entirely independent in terms time and frequency.

Saving Water in the Garden – Do You Have to Rely Only on Slow-Growing Plants?

Many of the water-conserving plants available to gardeners in dry climates are slow growing. It is one of the prices that has to be paid for growing beautiful landscape ornamentals that require little or no irrigation through the year. The dry climate garden would be all the poorer without species of Grevillea, Myrtle, Pistachio, and Melaleuca, which are excellent plants but take a few years to reach the desired size. A number of species, particularly Grevilleas, actually suffer and decline following the gardener’s attempt to speed up their rate of growth by generous amounts of water and fertilizer.

An exception to this rule is Rhus, or more precisely, a number of species of the genus. Rhus, or Sumac, to use its common name, is a large genus with a wide, natural dispersion, including South Africa, North America, and West and Central Asia. Amongst the species most suitable to hot, dry climates are Rhus crenata, R. ovata, and R. integrifolia. They are fine landscape bushes, providing a quick, evergreen, and attractive screen. They can also be trimmed as a neatly clipped hedge.

Unlike some of the afore-mentioned plants, these Sumac’s will not decline as a result of regular summer irrigation and feeding, providing that the drainage is adequate. On the contrary, they will respond well, reaching 2 meters or so within a couple of years or less. Once established, they can survive and thrive on a much-reduced regime, needing some 200mm of irrigation in climates that receive as little as 250mm of rainfall per annum. An annual spreading of compost should suffice as far as feeding is concerned. These evergreen types are hardy to both the winter and summer temperatures of a typical Mediterranean climate.

In design terms, they combine well with the usual Mediterranean - climate favorites such as Pittosporum, Leocophyllum, Raphiolepis, and Viburnum; plants that typically have a fine to medium foliage texture. Indeed, adding a purple-leaved variety of a plant like Vitex trifolium makes for a beautiful combination, as the similar leaf shapes are offset by the contrast in foliage color.

Sumac is often associated with the dreaded Poison Ivy. While the plants are related, Poison Ivy is classified as the genus, Toxicodendron. While some Sumacs are liable to be allergenic, the species mentioned are not noted for their toxic properties.

Conserving Water in Your Garden – How to Grow Australian and Other Dry Climate Plants

Conserving water is obligatory for gardeners in Mediterranean and other dry climates. For this purpose, a number of plants are suggested by nurseries and in garden literature that can be grown on very little or even no additional irrigation through the year. Many of these drought-resistant plants, known as xerophytes, are of immense value as landscape, garden ornamentals. Many originate from the dry regions of Australia.

Unfortunately, professional and home gardeners are aware of the relatively high failure rate amongst Australian plants, and as a result, species and varieties of Grevillea, Melaleuca, Eremophila, and Myoporum, to give a few examples, are loosing their appeal. This is a great pity, as a large number of trees, landscape shrubs and sprawling ground covers belonging to these genera are both beautiful and functional garden plants.

However, a better understanding of the growing requirements of these plants should result in reducing the mortality rate to the point that a small amount of failure is both acceptable and tolerable. The essence of the problem is that gardeners tend to care for them in the same way as sub-tropical species such as Citrus trees, or herbaceous perennials and even annuals.

A maintenance regime based on frequent watering and generous feeding may be suitable for most garden plants, but not for many drought resistant ones from Mediterranean climates, and especially for Australian ones. What in short should you be doing to give your Grevillea, Hakea, and Banksia e.t.c. bushes a better chance of surviving and thriving?

Good Drainage

Xerophytes are far more sensitive to a lack of air in the soil, than a shortage of moisture, so good drainage is the prerequisite for avoiding disappointment. Some plants, such as Banksias need perfect drainage, but few or none can tolerate anything resembling boggy conditions.

Minimal Feeding

Almost all species from the Proteaceae family, to which many Australian and South African xerophytes belong, are highly sensitive to excessive levels of salt and fertilizers in the soil, and especially to phosphorous. While compost improves the soil’s porosity, excessive quantities are liable to release too much mineral nutrient in the root zone. Similarly, Junipers, which are largely of Asian and Mediterranean origin, suffer from high doses of nitrogen fertilizer. Their nutritional needs can be more than catered for by compost or worm castings.

Patience

Species of Melaleuca, Myoporum, Grevillea, e.t.c. have to be allowed to grow at their own pace, and not forced by frequent irrigation and fertilizing to grow rapidly. In fact, this often causes plants to suddenly collapse after a year or so. Watering should be kept as low as possible just to ensure the young plants’ survival, and not in order to force them to cover space quickly. It follows therefore that as well as specific irrigation, soil, and feeding requirements, many of the excellent garden plants that are ideally suited to dry climates, need a good dose of patience from those in their care!

Grevillea – Fine Landscape Garden Plants for a Dry Climate

Grevilleas are woody, evergreen plants from Australia, including a large number of species and garden varieties, ranging from tall trees and large bushes, to low-growing sprawling shrubs. Usually they have a very distinctive leaf shape that gives the foliage a fine, feathery texture, and the long, slender flowers, typical of the Proteaceae botanical family.

In addition to being garden plants of much ornamental value, their great merit is in their modest water requirements. In near-desert climates that receive only 250 mm of rainfall a year, Grevilleas can be grown on as little as 200 mm per year. In temperate Mediterranean climates that receive some 400 mm a year, established plants can get through the summer with virtually no additional irrigation. This makes them essential plants at the disposal of the dry climate gardener.

Due to their fine foliage texture, Grevillea shrubs are most suited, stylistically speaking, to Mediterranean gardens and in association with plants of similar leaf size and shape. They combine beautifully with types of Juniper, Melaleuca, Pistachio, Leucophyllum, as well as Rosemary, Lavender, and shrubby Chrysanthemums, to name but a few examples. They are especially appropriate with other ornamental Proteas, such as Banksia and Hakea.

On the other hand, they look out of place with large-leaved, course textured plants, and so are unsuited to tropical style compositions. A specimen, rather like an ingredient in a cooked dish, is only as good as its place in the scheme of things.

Growing Conditions

Despite being hardy to drought and to the lowest temperatures that a Mediterranean climate is likely to reach, Grevilleas are not entirely easy to grow. They are very sensitive to poor drainage, and are liable to degenerate under conditions of frequent, shallow watering. Many species are intolerant of high salt levels in the soil, a condition that is all too prevalent in dry climates. For this reason, occasional, deep irrigation is necessary to leach excessive salts from the soil.

Like other genera belonging to the protea family, they suffer from excessive levels of phosphorous present in the soil. It is best therefore to avoid applying chemical fertilizers, or at least those high in phosphorous. This is yet another argument against the use of automatic fertilizer pumps, which consistently add to the soil, salts in general and phosphorous in particular. On the hand, Grevilleas tend to be sensitive to root disturbance, so digging in compost around the plants should be exercised with great care.

Despite these drawbacks, as well as a fairly high mortality rate amongst new plants, the various trees, shrubs and ground covers belonging to the genus Grevillea, are too valuable as ornamental landscape plants, and too useful as water-conserving plants, for the gardener in a dry climate to ignore.

Morning Glory Ground Covers – Excellent Plants for Mediterranean Gardens

Morning Glory is commonly associated with rampant climbing plants belonging to the genus Ipomoea. There is however a species known botanically as Convolvulus sabatius, (C. mauritanicus) which while having climbing properties, can be grown as a low-growing ground cover plant. Considering that its water requirements are very modest, and that is so easy to grow, it is an excellent plant for gardens in Mediterranean and other dry climates.

Convolvulus sabatius is a semi-woody perennial that covers about 1 meter (3ft) in each direction, reaches some 30 cm in height (1 ft) with small, oval shaped leaves of a medium green hue. The foliage is not especially attractive, but the lavender-blue, bell shaped flowers create a stunning carpet through much of the summer. A path of flagstones meandering through this pastel sea of lavender is classically Mediterranean in style.

Some gardeners may be put off by the name Convolvulus, associating it with the infamously noxious Bindweed, Convolvulus arvensis. The garden species can be invasive, but this tendency is easily kept in check by hand weeding and occasional monitoring. It can also be a nuisance by climbing its way up nearby herbaceous plants and smothering other ground covers. The answer is to keep a good distance between the Morning Glory and its prospective neighbors!

As mentioned, Convolvulus sabatius is easy to grow. It requires trimming at the end of the winter to prevent it become bald and woody. It prefers less water to more, but does need well-drained soil. Frequent watering tends to produce more vegetative growth, while the occasional soaking seems to induce more flowers. It grows satisfactorily on less than a quarter of the water needed for grass, and even less compared to annual flowers.

The flowers of this Morning Glory reach about 25cm wide (1in) and their bell shape combine beautifully with flowering plants belong to the Deadly Nightshade family, (Solanaceae) such as Solanum rantonetii and Nierembergia, and with other bell-shaped flowers of similar size, like Penstemon. Always bare in mind that flowers possess shape, size and texture as well as color, and that mixing radically different flower shapes together, looks incongruous and out of place. Therefore, Convolvulus sabatius should not planted next to large, garish, tropical type flowers.

Ground Cover Plants for Replacing Lawns in Dry Mediterranean Climate Gardens

In temperate-Mediterranean climates, where annual rainfall reaches about 450mm, (18in) lawns need at least 700mm of additional irrigation through the hot, dry summer. That is, 700 liters per square meter per year. In drier climates, where annual precipitation does not exceed 250mm, (10in) this figure can rise to over 1,000mm a year.

Many ground cover plants on the other hand, can survive, grow, and prosper on up to 200mm of extra water, and some, when established, and providing that the rainfall for the year has reached 250mm, do not require any watering at all. While ground covers cannot replace the functional role of grass, such as playing and sitting, they can definitely be considered where there is no real need for a lawn. Ground covers for instance, are a far better option than grass for the narrow space at the side of the house, especially in shady spaces facing east, northeast.

Beautiful, low-growing plants with delicate leaves create a fine, frothy, textural quality, which is far more interesting than a flat, two-dimensional lawn. Subtle variations are achieved by the different shades of green available. Think of the dark, heavy green of Rosemary and Trachelospermum, combining with the fresh, light green of Baccharis pilularis, or Asparagus densiflorus “Sprengerii”. Low-growing species of Grevillea, with their fine foliage and striking red blooms, can takeover from a swathe of the very prostrate Myoporum parvifolium.

It is also possible to dot a few taller, narrow plants amongst the groundcovers, in order to create a vertical emphasis, accent, or “exclamation point”. Nandina domestica, (Heavenly Bamboo) with its attractive form and delicate foliage, fits the bill perfectly. It is also modest in its water requirements. Alternatively, grass-like ornamentals like Phormium tenax serve the same purpose.

Flowering ground covers, or ground cover plants that need full sun, fall into a separate category. It is important with these, not to shade them out by planting larger plants too close by. Many prostrate succulents, or ice plants, can be very exciting with their seasonal blooms, but they do require considerable care and attention to ensure they look presentable through the year. A sea of Lampranthus in flower for instance, is a sight virtually unmatched in gardening, yet the plant invariably looks untidy and leggy if neglected.

Ground cover plants are not a “substitute” for grass. Children cannot play on them and you can’t have a family picnic on them. Neither do they provide that neat, open view that we know and love with a lush green lawn. Ground covers have an aesthetic and design value of their own, which combined with the possibility of saving oceans of water, makes them so essential to the gardener in a dry climate.

Garden Design Ideas – Landscaping Gardens Using Less Grass

Water shortages in dry climates are forcing home gardeners and professional landscapers to reduce the area of the garden taken up by the lawn. The trouble is that nothing that can replace a lawn in the field in which a lawn works. Young children cannot play as safely on hard paving, you can’t really play soccer on wooden decking, and it’s hardly practical to lie down on a bed of ground cover plants, as one would on grass.

Yet a garden whose area is 90% grass, is as unviable as it is unsustainable in dry and semi arid regions such as the Mediterranean, much of the American west, Australia, South Africa, and the Middle East. The only way forward is to rethink the garden’s design concept, by moving away from large open spaces, to smaller, more intimate ones. Here are some means by which the problem can be approached.

Enlarging the Shrubberies

The width of the shrub and bush border can be enlarged at the expense of the lawn. The usual habit of planting shrubs in a thin line at the lawn’s edge, results in a lack of proportion between the two spaces. A wider border on the other hand, creates more depth and perspective. Most shrubs can be grown consuming at least a quarter of the water required by grass, and some plants such as Junipers, Leucophylum, or Pistachio, on a lot less. Think of the saving when the 50cm strip at the lawn’s edge is replaced with a bold space some 2 meters wide.

Designing with Ground Cover Plants

Water conserving plants of prostrate habit can form a transition area between the lawn and the shrub border. These can create a satisfying link to the trees and shrubs, especially if their leaf texture is similar to that of the tall plants. For example, Asparagus densiflorus “Sprengerii”, associates beautifully with Junipers, Melaleucas, and other thin-leaved bushes. Low-growing species of Cotoneaster combine well with roses and other shrubs and trees from the rose family, such as apple, plum, hawthorn, and pyrocantha. Transition areas of ground covers could reduce lawn space by over 20%.

Adding Seating Areas

Adding a seating area of decorative paving stones or wood decking brings different parts of the garden together, and makes for a more interesting and usable space, than the patio, lawn, border formula of the common suburban plot. A seating or paved area is of course a space that consumes no water.

What about Artificial Grass?

Simply replacing the lawn with fake grass, however convincing the new products are in visual terms, is not likely to achieve satisfying results in the long term, mainly because plastic cannot replace either the smell or touch of grass. However, artificial turf could be a satisfactory medium in a highly stylized, contemporary, garden design, which is minimalistic, austere, and angular in character.

Artificial Grass is not an Alternative to a Real Lawn

Installing artificial grass is an option that many homeowners are considering today, given the difficulties involved in successful lawn maintenance. Nowhere is this trend more prominent than in Mediterranean and other dry climates, because of the excessive water use that growing a lawn involves.

Despite the relatively high cost of installation, the customer may be tempted by arguments that point to virtually zero ongoing expenditure in time, money, and water over the ensuing years. Synthetic grass companies can also legitimately claim that recent technological advances have greatly improved the quality of the premium products, well beyond the worn-carpet appearance of the artificial turf we knew and loathed just a few years back. In short, there are plausible arguments in favor of using artificial grass, but does it follow that an artificial lawn is a viable alternative to a real one?

A lawn’s architectural role is to provide a neat, green, and even ground plain. This, at least theoretically, can be matched by the best synthetic product. However, in its functional role for sitting, playing, and general use, grass affects not only the visual senses, but those of smell and touch as well. Compare picnicking engulfed by the fresh smell of grass to the delightful fragrance of plastic! How is it that sports persons playing on artificial turf tend to get burns after falling and sliding on the ground? Grass increases the volume of oxygen we breathe, while plastic burning in the hot sun, adds toxic vapors to the immediate vicinity. Which is preferable for your children?

In design terms, synthetic grass should be seen for what it is – namely fake grass. The fake is always inferior to the original, although sometimes, when a material is not pretending to be what it is not, it can be used to good effect. Hence, a path constructed from poured concrete can be a satisfactory and much cheaper alternative to ceramic tiles, or glass fiber containers, can look just as good as Terracotta pots. In both cases though, both the “fake” and the “natural” are artifacts that have undergone some synthetic process, whereas grass is comprised of live organisms, which no alternative material can replace.

As lawns are the biggest consumers of water next to annual flowers, gardeners in dry climates are desperately looking for ways to reduce water use without affecting the aesthetic and functional properties of the garden. This is best done by re-thinking the garden’s design – paved seating areas, water-conserving ground cover plants e.t.c. instead of the false notion that artificial grass can simply replace a real-live lawn. Synthetic turf may be a viable water saving option in certain municipal situations, such as in traffic circles and road islands, but it is rarely successful or satisfying in the home garden.