An unpleasant situation that can arise in gardens is when the lawn grass starts to spread out and invade the neighboring planting beds. This issue is particularly pertinent to hot, dry climates, because usually, heat hardy perennial varieties such as Bermuda, Kikuya or Zosia are grown.

These, unlike grasses grown from seed, spread aggressively by way of their under ground shoots known as rhizomes. Due to the massive network of roots, rhizomes and stolons (shoots that spread above the ground) removing the invading grass by hand, whether with a tool or not, is virtually impossible. You can spend all day digging out the offending grasses, only for them to return after a number of days.

This is when unwanted plants, or weeds, become unmanageable. No one can expect the garden beds to be absolutely free of weeds, but on the other hand, the wise gardener will be looking to avoid weed infestations that get out of hand. With regard to the lawn growing where it should not, it's crucial to keep the edge as well cut and defined as possible. This requires some attention on a regular, preferably weekly basis. At the first signs of spreading, simply pull or cut out the grass. This will not of course kill the intruders but prevents, more or less, the lawn establishing itself amongst the bedding plants.

It is mistaken to believe that edging materials limit the subterranean growth of the afore-mentioned lawn types. Bearing this in mind, it may be worth considering, choosing a perennial turf species that spreads by stolons (above ground) as opposed to rhizomes (below ground) Examples of such grasses are Buffalo, (Buchloe dactyloides) and St Augustine grass (Stenotaphrum secundatum) Needless to say the latter types have to be suitable to the growing conditions prevailing, but that being said, they are far less damaging to flower and ornamental beds because they are so much easier to eliminate manually.

So what can be done if you do find yourself confronted with a planting bed being overrun by the encroaching lawn. Assuming that constantly hand weeding the bed is not a realistic option, you may consider spraying the grasses with a selective herbicide that kills grass weeds without damaging the broad leaved plants. T

he trouble with this option is that applying the herbicides at the recommended low concentration retards the growth of the perennial grasses, but does not eliminate them. From my experience, the spraying is effective for a few months only. Now it's one thing using poisons occasionally, very occasionally, but it's quite another to be applying them as part of a regular routine.

I think that route should be avoided at all costs. In fact I prefer in these cases, to kill all the small plants in the bed, ornamentals together with the weeds, by use of a systemic weed killer like "Roundup" (Glyphosate) applied at a strong enough concentration, and then replant the bed. An alternative, less drastic albeit more tedious method is to paint the grass weeds with Glyphosate, taking care to avoid the solution dripping on the bedding plants.