In good open ground, plants take their nourishment from the soil and their moisture requirement from the rain, but in containers they are totally dependent for their existence on the conditions provided for them initially, on quality consistency of care and attention devoted to them subsequently.
It is important to identify four basic needs for plants. At the time of planting they need adequate drainage and a suitable growing medium and, on a long term basis, regular watering and feeding. Firstly, drainage, and whatever the type of container, it should have adequate holes in the bottom to allow excess water to drain freely. Raising the base of the pot may be necessary so that it is slightly off the ground to ensure that water runs away – although this should not be necessary if the pot is standing on a base of shingle, gravel or some other aggregate which is itself a free-draining material. To prevent the drainage holes becoming clogged, a layer of crocks from broken clay flower pots should be placed in the bottom before compost is added. If these are not available you could use pebbles or fired granules of clay or cinterized ash of about ½ in (13mm) diameter. Whatever you decide to use, it is a good idea to place on top a layer of coarse peat or a few pieces of well-rotted turf.
Watering container plants in the morning has had great results, also watering them in the evening and in spring and summer is also essential; at least once a day – certainly a general rule. A large specimen growing in full sun in the summer may also need to be watered again around midday, although you should take good care not to wet the foliage. However, for plants like hostas and ferns growing in a damp shady place twice a day would be too much.
Watering can sometimes consume a lot of time, especially if you choose to use a watering can as we do, rather than a hose pipe. Do remember that the more containers you have, the more work is involved. It is possible to regulate the time it takes to water plants much more effectively by repositioning containers near to each other in the garden, opposed to placing the odd one or two in numerous different locations.
Plants should be fed in the growing season. If you use a can to water, its easy to add a measure of general liquid fertilizer whilst filling the can at the tap. We feed container plants around once a week, again using judgment and feeding even more frequently any plant that looks a little sickly. Do remember to water the container before feeding, because if you pour diluted fertilizer on to dry soil it will simply wash through without having a chance to be effective.
In spring it is a good idea to fork out gently the top inch or so of compost in the containers of long-term plants. Tease up the new surface and then add a layer of fresh, new compost. You could also add a sprinkling of bone meal or granular general fertilizer at the same time, as an extra feed. Indeed, there are other ways of applying fertilizer to container plants – even a pellet which can be placed just under the soil surface to give slow-release fertilizer and weed killer combined.
In spring our trolley is in constant use, bringing hostas out of winter hibernation or moving the specimen Acer palmatum dissectum into the sun. This is a beautiful, mature plant in a heavy pot and early in the season as the delicate foliage starts to break we tend to leave it on the trolley so that it can be moved easily in response to weather conditions. We are anxious to avoid burning by the sudden warm spring sunshine or damage from a sharp easy wind; as already mentioned, acer leaves can be delicate and should be monitored during the blooming sun as brown specks would spoil the whole look of that lovely foliage effect.
On the subject of weeds, these should obviously be removed from containers as soon as they appear – a job that only takes a minute or two. Even when container plants are established you may still want to move them around the garden from time to time – that is, after all, part of the ever-changing interest of container gardening. For this job, it’s considered essential to have on hand a low, flat trolley on wheels or castors. The pot can be eased up on to the trolley using a spade as a lever.
Perhaps the largest of all the permanent plants that you might try growing in a container are trees. The idea may be rather more ambitious than you had contemplated, but if you have a yard with no plant beds or a basement garden – even a large, open patio – height is important. It can be achieved with climbers around walls and on fences but in a pen position a small, graceful tree makes a superb centrepiece.
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