Kitchen Garden Forum

In The complete book of gardening tips by Janet Macdonald she says on page 115
"Add 1 tsp children's shampoo to 1 litre water for seed trays. This prevents the formation of a crust on the soil which seedlings can't get through"
Have any of you tried this ? I could just buy some baby shampoo and try it without planting any seeds as an experiment. I just wondered if everyone else already does this ?

Ah-ha someone adding a wetting agent.

Hi Happymouse,
Good proprietary brands of compost already have a special wetting agent added.With your experiment, to test the compost, water some with the said shampoo mix and some just normal water and note the difference.
I use Vitax MP compost and that has a wetting agent and to treat with shampoo would be OTT.
You can also use washing-up liquid to do the same thing.
If you by mistake have a pot that dries right out it is best to use water with a detergent to make the water stay instead of running straight out of the bottom of the pot. If possible steep them in the solution for a short while.
JB.

Many thanks Peter and Johnboy. I did not know this. I used a multipurpose compost and all the pots of flower bulbs I planted weeks ago have a thick crust on them. Hopefully the poor bulbs will see daylight now. This is probably why my freesias in pots grew all wonky last year.

I bought some multipurpose compost with wetting agent. I use capillary matting with the pots and trays sitting on it, everything got far too wet and rotted so I ditched the lot.

You need to be very careful if you use a detergent because many of them are oil-based. The secret is to use much less than you think you need. Years ago I sprayed some sprouting broccoli with what I thought was an extremely dilute solution of washing-up liquid and the leaves all turned brown as a result; the solution was too thick and the oil-based detergent had suffocated the pores through which the leaves transpire. I haven't dared do anything like that again.

mike

Hi Mike,
I take your point which is very valid, but we are not talking about treating foliage we are talking about treating the compost and the foliage of the plant should not be affected at all. I agree that the quantity of detergent must be to say the least sparing. I have only had to use this a couple of times and have had no difficulties.
I suspect that you were using detergent as a substitute for soft soap to remove aphids from your Broccoli which is something I would not recommend
although there are several contributors that have recommended using washing-up liquid to do exactly the same thing on this forum over the years.
JB.

Hi Allan,
Most proprietary brands of peat based compost have a wetting agent added and I too have used a capillary watering system at times past and I feel that you either had a duff batch of compost or you were applying too much water to the capillary matting because it is a case of the more water you give the more they will take.
JB.

Now I have changed to B&Q multipurpose there is no problem. The extra wet one was Erin, they make a feature of it on the sack. I have depended on a capillary system for at least 30 years with very little attention.The matting must be saturated at all times. BTW I always cover it with microperforated film to minimise the green stuff.

what exactly is 'soft soap'?

Johnboy: why would you not use washing up liquid solution to kill aphids? your reasons?

Its quite common advice to use a bit of washing up liquid solution to kill aphids on say broad beans and basil.

I've heard detergents are actually quite bad for plants, so I think if you were putting more than the tiniest drop in a litre of water it could harm the plant.

Hi Dewwex,
What may be kind to your hands is not always as kind to foliage which is somewhat more tender than hands.
WUL is not made for horticultural purposes. Now that sounds daft but there are detergents that are used in the trade which have been proven to be kind to foliage.
Soft Soap is really just what it says soft soap and it has fatty acid qualities and has clinging qualities where detergent have not. Soft soap will, by it's properties, kill an aphid and detergents simply gives it a good bath and sends it onto the next person.
JB.

But what is 'soft soap'? Is a bar of soap soft soap? Are liquid handwashs soft soap? What household product contains 'soft soap'?

Is Soft soap, insectidial soap, fatty acid solution just really different names for the same thing?.