Hot weather potted plant care
In summer, looking after house and container plants can be a daily activity.
Outdoors container-grown plants, once their roots fill the pot, can need watering every day and on some days, twice.
Outdoors hanging baskets are heavy users of water, losing more moisture than containers sitting on the ground.
Indoor potted plants will likely need watering once or twice a week, or even more frequently.
Outdoor container plants growing in potting mix dry out faster than those growing in compost, even if wetting agents have been applied.
While there are potting mixes that are still peat based or contain peat moss, most potting mix these days is largely bark fines with added slow release fertilisers, some lime and other additives.
Ideal for indoor plants, potting mixes are in my opinion a waste of money for outdoor use.
When potting mix dries out, it creates a surface tension which does not allow water to penetrate. Liquid tends to go to the sides of the pot before running out the drainage holes, so the plant misses most of it.
Friable purchased composts retain water far better and will accept water much more readily than a pile of bark fines. If water runs out the drainage holes quickly, there are a couple of tricks to thoroughly moisten the mix.
Fill a large tub or bath with water and plunge the containers into it and watch them bubble. The more bubbles, the more dry areas there are. When it stops bubbling, the mix is wet right the way through. Lift and allow excess water to drain out.
Punnets of seedlings should also be plunged before they are separated for planting out. A weekly plunge will benefit outdoors hanging baskets too .
If treating indoor plants this way, do not do it in direct sunlight, and leave them in a shaded area to drain.
For large containers that cannot be plunged, fill a bucket with warm water and add a good squirt of dishwashing liquid. Agitate the water to make it soapy, then slowly pour the contents over the top of the mix soaking all the surface areas. The soapy water breaks the surface tension and allows water to penetrate. You can use this same method on gardens and lawns for dry spots – areas of dried grass on lawns surrounded by a ring of healthy grasses.
Spray Vaporgard over and under plant foliage. One spray will last for about 3 months and will also help reduce disease and insect damage.
Be aware that most disease damage to container plants is caused by overwatering, something that needs watching as autumn approaches.
Powdery mildew can also be a problem as the weather cools. Sprays of baking soda and Raingard will protect foliage from this problem.
For plant pests such as mealy bugs, scale, thrips, aphids and the like, a solution of Neem Tree Oil at 25mls per litre of warm water can be watered over surface sprinkled neem granules when the medium is moist.
If the plant has mites, spray with Liquid Sulphur – but not in conjunction with Neem Oil or if Neem Oil is present on the plant.
Container plants need special care during the hot summer months. The trick is to provide enough moisture without overwatering.