Some of the following recipes and products have been mentioned on other pages. Let me know if you have any other recipes. The items are listed in alphabetic order.
Chilli-based Natural Pesticides
HDRA has a useful document on recipes for chilli-based pesticides. They can be used against a variety of pests. Be careful with regard to the strength of the mixture, as plants can easily be burnt if it is too strong. Also, the usual warning applies – handle chillies with care as they can irritate eyes and hands.
Comfrey Liquid Feed (High Potash)
Place lots of comfrey leaves in a barrel or large container. Weigh the leaves down with a brick or piece of wood.
Leave for 3-5 weeks. It will become very smelly!
Dilute (15 parts water to one of the liquor) and use as a potash feed on crops such as tomatoes.
Nettles can also be used – see below.
Several recipes for deer repellent sprays can be found on the Internet. They are generally based on the use of eggs although they may be better deployed in keeping deer off ornamental plants rather than food. The treatment needs to be repeated every couple of weeks or after rain.
This recipe was located by a Sunningdale plot holder.
Diluted Washing-Up Liquid (or Soft Soap) to Control Aphids
Use one teaspoon of washing up liquid with 2 gallons of water. Note that it needs to be very diluted otherwise it can easily burn the plants. Some people recommend the use of soft soap rather than washing-up liquid, as it does have some insecticidal qualities and is less harmful. This approach should be regarded as a preventative measure: spraying should be done regularly, typically weekly, to be effective. This is a contact spray, i.e. any aphids on the underside of leaves that are not sprayed will be unaffected.
Dried Crushed Eggshells
They are used to keep slugs away.
This is a horticultural fleece product which has become quite popular (although I have not noticed anybody on our site using it so far). It has a fine mesh, and it is typically used to provide a physical barrier, keeping flies and butterflies away from crops, e.g. cabbage root fly, carrot fly and leek moth. It is relatively expensive but it will last 7-10 years. It can be cut into desired lengths / shapes. There are a number of suppliers.
Fungicide Made With Washing Soda and Soft Soap
Per gallon of water the ingredients are:
2.4oz washing soda
1.6oz soft soap
1 gallon of water.
This fungicide is effective against mildew on gooseberries. It could also be used on blackcurrant varieties that suffer from mildew.
Garlic-based Natural Pesticides
Here is an approach that one gardener (not a plot holder) swears by. “One clove of garlic (zapped in the microwave for one minute with a tablespoon of water), added to one pint of water, liquidized and strained. The addition of a soap agent is supposed to help the spray to adhere but I don’t bother. I’ve found it very effective.”
Garlic is a recognised key constituent of many homemade insecticides. HDRA provides a useful document on various garlic-based recipes. However, it should be noted that it can kill beneficial insects as well as pests. Therefore, the spraying needs to be done with some care. Also, be aware that the smell of garlic can remain on the crop for up to a month – so possibly better not to use it near harvesting time.
This is not actually a recipe – it is a biological product. It contains nematodes that will kill slugs, particularly those that are resident in the soil. It will keep in the refrigerator for two weeks. It is mixed with water and applied using a watering can with a rose fitted. It is particularly effective on potato and root crops. It is not cheap although there is a considerable volume of the product when mixed with water. It may be more cost-effective to share a pack with another plot-holder unless you have a particularly large area to cover.
Further information can be found at http://www.nemaslug.co.uk/
Nettle Liquid Feed (High Potash)
Place 2lb of nettles in a bag with a half inch mesh (e.g. onion or seed potato bag)
Place the bag in 2 gallons of water, weighing it down with a brick.
It will be ready in 3-4 weeks (though the smell is somewhat unpleasant).
Dilute (10 parts water to one of liquid feed) and use as a potash feed on crops such as tomatoes.
Pernicious Perennial Weed Control
Weeds such as ground elder, couch grass and bindweed can be controlled by planting Mexican Marigolds (Tagetes Minuta) within 30cm. Cut the weeds down to ground level first. Secretions from the plant (produced 3-4 months after sowing) have a herbicidal effect on some plants and inhibits their growth. Beware that the plant can grow up to 2 metres in height. Read this for further information.
Powdery Mildew sprays
In an effort to avoid powdery mildew make sure that the roots are always moist as dry roots can be a contributory cause. Cut out affected parts of the plant befor spraying – unless of course the whole plant is affected.
There are two methods:
- using milk and water. See this recipe. This is best when used as a preventative measure.
- baking powder in water. See this recipe. This can be used on a problem plant, ideally after cutting out the worst affected parts.
Rhubarb Insecticide to Control Aphids & Small Caterpillars
This is an alternative to the diluted washing up liquid. Beware that Rhubarb leaves are poisonous (to eat) and old utensils should be used as they will be stained:
Boil two pounds of rhubarb leaves in a few pints of water for about 15 or 20 minutes.
Allow to cool.
Strain the liquor into a suitable container. Dissolve a small amount of soap flakes or washing soda in this liquid – too much may burn the plants.
Rhubarb Leaves to Control Club Root
There are two approaches:
- Boil some rhubarb leaves in water and pour the resultant liquor into the planting holes
- Simply put rhubarb leaves into the planting holes.
Tagetes-based Natural Pesticides
HDRA has a useful document on recipes for tagetes-based pesticides that can be used against a variety of insect pests.
Page last updated on December 9th, 2017.