Plant Knowledge

[STEVIEBOY1]

This may sound an odd question for this forum, but here goes, owing to the recent very wet, then very dry hot weather, in this part of the UK, the South East, a number of my potted plant cuttings, geraniums, lobelias etc, have a lot of foliage but not too many flowers so far, although there are a few buds, also many of the leaves have quite a yellow tinge, could that be because I may have over watered the plants in the hot dry weather? also, how does one propagate geraniums for next year? Many Thanks.

 

[mac]

mine to plants i bought from a big diy centre are rubbish but ones from local garden centre are perfect.

 

[Ploughman]

I have been advised by She who knows.
That your Geranium problem sounds like lack of food, try a little bit of Tomato food such as Tomorite.
Cuttings should be taken as Softwood cuttings. Look it up as it's a bit technical for me as well.

General advice the best plants will always be found at a Nursery followed by a Garden centre or dedicated Plant Fair and never unless desperate from a DIY shed.

 

[michael769]

Yellowing of geranium leaves is indeed a sign of water stress.

Yellowing round the edges indicates a lack of water. Yellowing of the entire leaf (possibly accompanied with pale "water spots") indicates over watering, typically the yellowing affects the lower leaves nearest the roots. Geraneums are drought tolerant and require little water, so you should discontinue watering to allow the plants to recover.

If the entire plant is more yellow than green it may be a lack nutrients, and a liquid feed should be used. Avoid tomato or other high potash fertiliser as the low nitrogen content is unsuitable for geraniums and other flowering plants.

If the plants appear stunted or mishapen and wilting, it may be a serious fungal disease, verticillium, in which case the plants need to be lifted and burned or disposed of in the domestic waste (not on a compost heap). The soil will also need to removed and disposed of.

 

[DaveNewcastle]

I reccommend Michael769's assessment.
My plant food mantra is Nitrogen for leaves, phosphorus for roots and flowers, potassium for stems and fruit.

But one thing that makes this more complex is that these 'off the shelf' nutrients can't do the work all by themselves - microorganisms in the soil are necessary to convert these elements/compounds into absorbable fluids, so the quality of soil is crucial too.
Yellowing leaves, in the way you describe probably are from over-watering, but there are all sorts of potential problems with pot-bound plants that may be factors - watering from the top, air gaps in the pot, infection in the soil, dead roots, too much root vs. soil, poor soil quality, drainage problems.

If it helps (I know it won't!) BBC's 'Gardener's Question Time' has been running for decades and still the 'expert' pannellists manage to disagree with almost every 'solution' to a problem.
My take on all this? A plant has a life of its own. I can nudge it, support it, and even try to kill it. But what it does is what it does.
It probably won't have too much influence on me, either! (though my left arm is itching badly after 2 hours removing brambles, nettles and budlea today. So maybe they win).

 

[michael769]

On the subject of fertilizing flowering plants. I generally use balanced (High nitrogen) fertilizers during the spring and summer to encourage leaf and flower development. I use a commercial all purpose liquid feed for containers, for my beds I use pelleted chicken manure applied in the spring.

For perennial flowers in containers I switch to a high potash fertilizer in autumn to encourage root growth and discourage new young top growth (that will just be damaged by frost) as this sets the plant up well to survive winter.

For annuals I continue to use a balanced fertilizer until the first frosts kill them off.

DaveNewcastle is right about the plants having a life of their own. I have learned over the years that it is futile to try to grow plants where they don't want to grow. So these days I prefer to plant what I know will do well in a given location, and in doing this I can for the most part just let the plant get on with it with very little care.

 

[LexyBoy]

When you say geranium "cuttings" do you mean small plug plants you've bought, or actual cuttings fairly recently taken by you or a friend? If they're actual cuttings then they could well be stressed by the weather as they won't have well developed root systems.

I'd hesitantly agree with the above posters - although if your plants are in fresh compost (not re-used from the previous year) then I think it's unlikely to be due to lack of nutrients. It could be down to the wet weather, although when it's really hot it's hard to overwater. Being in a shaded spot will also slow down growth and especially flowering.

For your question on how to propagate geraniums, it's really easy to take cuttings. First select healthy shoots, and remove the top 5 cm or so of stem. Remove the bottom leaves leaving 3-4 leaves at the top, and pinch off any flower buds forming. Next insert the bottom 2-3 cm into slightly moist, well drained compost (you can use rooting hormone if you have it, but it's not essential) and keep somewhere warm, shady and well-ventilated. The most important thing is to avoid overwatering - geraniums are semi-succulent so have enough stored water to last a while, and sitting in wet compost will lead to rot. After a month or so you should see the cutting start to grow again at which point you can move it to a brighter spot and start watering more regularly (don't leave it sitting in water though).

Your existing plants should be fine throught the winter too, just keep them very dry and remove dead leaves to prevent diseases.

 

[STEVIEBOY1]

Thank you for all the infomation here. Rgds.