Pot-grown plants are like caged animals; being confined, they can’t ‘forage’ so they rely totally on us for food. Most compost only supplies ‘starter’ nutrients that are soon used up, so begin feeding plants growing in pots six weeks after potting or repotting.
The amount of feed plants need varies according to growing conditions, size and speed of growth. Some people underfeed, while others overdo it. If you apply a strong dose of feed all in one go, the resulting strong solution of salts can actually draw moisture out of the plant by a process known as reverse osmosis, so over-feeding does more harm than good.
Always follow the feed supplier’s advice, but as a general rule start feeding in spring, perhaps once every two weeks. Feed weekly when plants are growing vigorously and the weather is warmer, rising to twice weekly for heavy feeders or fast-growing plants in large containers.
Check out these tips on feeding your potted plants, below.
Using liquid feeds
Use liquid feeds for plants in pots and containers; it can be too easy to overdose with solid feeds, which can scorch plant roots when applied to the surface. However, you can incorporate slow-release fertiliser into your planting medium when potting up plants.
Choose the right feed
Apply high-nitrogen liquid feeds to leafy plants and liquid tomato feed (diluted to half or quarter strength) to flowering plants, to promote buds.
Feed little and often
Feed little and often instead of big, infrequent doses during the growing season and increase feeding with speed of growth. Stop feeding at the end of summer.
Dilute your feed
Dilute liquid feeds, following the maker’s directions, and apply as much of the liquid as you’d use to water the plant. Don’t be tempted to add more.
Don’t feed plants that are under stress
Don’t feed plants that are under stress from root damage or drought (which will be wilting) until they’ve recovered.
Feeding those that need it
Remember, not everything growing in containers needs regular feeding. Generally speaking, cacti, succulents and hardy annuals perform best on poor soils. If you’re unsure, just do a little research around the plant to find out more about its growing requirements.