Hanging baskets are different to patio containers in that they normally have less volume for potting compost. The ratio of soil to plant is greatly reduced - especially as we tend to cram as many plants as posible into hanging baskets and window boxes! (I am as guilty as anyone on this.)
This can lead to problems and disappointment with hanging baskets and window boxes, as they can dry out easily, or run out of food for the plants with the small amount of compost available.
It is important to use good quality potting compost – or maybe even a specially-prepared ‘hanging basket’ compost.
If you use normal multi-purpose potting compost, you need to add two further ingredients to ensure that the plants have the best possible chance of survival.
Water retentive Gel should be mixed with the compost before planting. These come in crystal form and are either mixed dry with the compost in your hanging basket or window box, or you can swell the gel with water beforehand. If you decide to mix the dry crystals in the compost, remember that once you water the compost, the crystals will swell considerably! So your compost could soon be pushing its way out of your hanging basket – at best simply overflowing.
The water retentive gel, really does cut down on the watering required – a boon if you pop off for a few days, and also a lifesaver for the plants as they thrive with a permanently moist compost!
Long Last feed such as Osmocote, will ensure that your plants will get fed for the whole season, simply by adding the Osmocote granules to the compost at planting time. Without this added feed, the hanging baskets and window boxes will nee to be fed weekly after the first two or three weeks.
Filling the Window Box
Place a few bits of broken stone over the drainage holes at the bottom of window boxes, to ensure that the drainage holes do not become blocked. With new plastic window boxes, make sure that the holes at the base are drilled out. Sometimes the new boxes are sold with the drainage holes sealed over.
Only half fill the box or basket with compost, then place the plants in position and feed compost down between the plants. This way, you will not have surplus compost in your window box or hanging basket as you try to place the plants in a full container!