In September, potted gardens recover after the hottest period of the year: from the middle of the month onwards, temperatures will begin to drop and rainfall will become more frequent, favouring a resumption of vegetation and new blooms. It is, together with May, one of the most satisfying months and many compare it to a second spring, but with warmer and more delicate colours.
To get the most out of our outdoor spaces we will have to devote ourselves to cleaning, irrigation and containment of phytophages and cryptogams.
Upon returning from the holidays, or simply because of the heat, we can find ourselves with pots a little ‘bare at the base, without flowers and with many yellow leaves. In most cases (especially for geraniums, petunias, verbenas…) we can intervene cutting and cleaning in a quite drastic way. Then we will follow frequent administration of liquid fertilizer and irrigation: we will see a rapid resumption of vegetative growth and production of buds.
Similar measures may be required for shrubs (roses), creepers or herbaceous shrubs that are re-flowering or flowering for a long time. If we have not done so before (July/August) we can proceed with pruning the shrubs that bloom on the old branches. By stimulating growth and tillering, the following year we will have more abundant buds and a compact habit.
Maintenance and propagation
First of all, we must continue the work of weed control: with lowering temperatures and rainfall, it is more frequent and growth is faster.
Many flowering plants (dahlias, sunflowers, aster september) have large corollas on high but delicate stems: to keep them as long as possible we provide guardians.
Most of the summer bulbous plants have reached the end of their cycle (e.g. gladioli, lilium, hemerocallis). It is not always necessary to extract them from the ground: we proceed every two or three years. We will have to check that they are free of mould and if necessary divide them from the side bulbs. We can then store them in a dry and cool place until the following spring.
It is also a good time for propagation: woody or semi-woody cuttings. They will root fast enough and we can invade them next spring. It is also a good time for sowing biennials and perennials: thanks to the mild climate we will have a fast germination and good growth.
Irrigation and fertilization
As we have said during this period we can allow ourselves to force the plants a little by administering greater doses of fertilizer. Thanks to the milder temperatures, they will not be damaged and, on the contrary, they will produce new vegetation and blooms. For herbaceous plants and small shrubs we prefer a liquid product, while for larger plants it is good to opt for slow release granules.
Irrigation is also important, but you must always take into account the temperature, the size of the pot, the substrate and the individual needs of the plant. When we return from the holidays, we are, for a few days, a little more assiduous, then we return to the habits of always. In general, rather than exaggerating, before going back to irrigating, it is better to wait for the soil to dry up in depth.
Work of the month on balconies and terraces in September: Pests and diseases
With the gradual change of season we also have a normal change of parasites and phytopathologies.
As temperatures fall and humidity increases, the red spider mite will become rarer, while aphids and cochineal infestations will continue. In less serious cases we can resort to macerates or pyrethrum, otherwise it is better to use more persistent products (pyrethroids, systemic or, for cochineal, white oil activated). With the autumn there is also a return of cryptogams (powdery mildew, scab, rust): let’s prevent them with frequent treatments with cover products, especially after the rains.
We also regularly check the leaves: by promptly eliminating those affected we will significantly reduce the spread.