episode 25 | show notes & advice
In this practical instalment of ‘Grow, cook, eat, arrange’, Sarah & Arthur have a whole host of processes, products and good advice to help you with your pots — and their preening, deadheading, watering and feeding. They also look at when to use a saucer under a pot and when to avoid it, and Arthur’s affinity for larger pots.
in this episode, discover...
- The combined strengths of SB Invigorator as a feed and for combating mildew and aphids
- How to best treat your container compost so that it supports thriving plants
- Why Arthur is a champion of big pots over smaller ones, and his tips for carefully watering them
- Tips on using nematodes to keep vine weevils at bay
- Ideal times of year to use, or avoid saucers under plant pots
- A selection of scented pelargonium varieties
links and references
Arthur’s whole garden is in pots and Sarah has huge numbers at Perch Hill, so they’ve both learnt over the years, what maintenance schedule is needed to have your pots looking good all summer and into the autumn.
Rule 1 - Planting medium (be it soil or compost) in pots needs to be of good quality
This is a top priority – you want GOOD stuff filling your pots. The key to pot success is investment in compost. If healthy and full of goodness, that will help massively with your pot success – and also helps with giving a wonderful display.
We only use peat-free composts and have trialled several such as SylvaGrow. They can vary a bit from year to year so it’s hard for us to firmly recommend one product.
Rule 2 - Feeding
3 weeks after planting (so usually in June), Arthur starts feeding, using liquid seaweed feed, the best universal feed for everything potted in the garden. He feeds fortnightly to start with, then moving to weekly by August. Follow the dilution instructions on the bottle.
Water once a day, in the morning at first light or in the evening (with a torch if needed).
As the season goes on, we not only increase regularity of feed, but also strength, moving to double strength of seaweed by September, and even in our greenhouse window boxes, triple strength by October to encourage them to continue flowering right through autumn.
Rule 3 - Pests
In the evening or first part of the night is when you can see pests e.g. slugs and snails and vine weevil. We both use nematodes (biological control) against these. If you’re seeing little, neat, in-cuts on petals or leaves, that’s probably vine weevil damage.
• SB invigorator
This is a plant tonic which is sprayed onto the leaves, feeding them and coating them in a thin layer that deters pests and fungal spores. Use it regularly to keep up the effect. It’s especially good on pelargoniums and houseplants. . At Kew, Arthur was taught to use it almost daily, but we don’t use it as often as that at Perch Hill.
Rule 4 - Watering
We don’t use water-retaining granules as sometimes we get a very wet summer and roots rot off.
And NO saucers under pots in the autumn, winter and spring as they will stay full most of the time and so rot off the plant’s roots. In summer it’s a good idea.
- Switch to big pots for your summer display rather than lots of little ones (which are fine in spring when we have so much more rain). The larger the better, as they are SO much easier to look after in terms of watering. Small ones need watering in hot weather morning and night.
- You can line terracotta pots with empty compost bags for summer displays which will help reduce evaporation from the sides of the pot as well as the top.
- Remember once the plants are fully grown, their foliage almost creates an umbrella over the compost surface so rainwater won’t penetrate, so move foliage aside and make sure you water into the compost.
- Take care not to over water species like Pelargoniums and arctotis (both from South Africa) at the start of the season until they are growing strongly.
- Dahlias are thirsty and need watering from the word go at least once a week. Then every couple of days from July.
- Drought stress stops flowering and causes mildew and other problems.
- Josie’s (the Head Gardener at Perch Hill) regime
- Try dividing your pots into groups with similar needs. You can then fit an irrigation system to each area. (We don’t have this as it means we can’t move our pots around as much as we both want to!)
Make it easy for yourself, so get a system with good hoses in plenty of places with a wand waterer for each group, to avoid you having to spend ages moving hoses around. Alternatively, you could place a watering can next to each water butt.
Remember if you’re using a hose, fill a can or bucket up with the first lot of water as this can be too hot for plants if it has been sitting in the sun, use it when it has cooled down.
Water each pot for a minute or so into each pot, watering into the centre, not around the outside, as the water can then just run down the outside of the pot with the compost dehydrated.
THEN CRUCIALLY go back to water each pot again. Rehydrated by the first watering, this second go around is when the water gets to the microroots.
For small pots, leave them soaking in a tubtrug or barrow of water for half an hour.
Rule 5 - Preening and picking or dead-heading
This means removing yellowing/browning foliage and picking all the flowers (or cutting off dead or going-over ones) Preen, preen, preen.
Picking the flowers to bring in, has the same effect as cutting them off once they’re over.
So, for winter and spring violas or summer petunias and cosmos, pick, pick, pick. Have flowers inside and encourage more flowers for your pots outside too.