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Grub grubs can be harmful to plants in flower pots, but they do not have to be in principle. In principle, only larvae of certain beetle species are considered pests. At the latest when several of them are cavorting in the substrate, you should consider measures to combat them. Chemical agents are not recommended and can be replaced with environmentally friendly and health-friendly home remedies that are just as effective. The plant experts explain what they are and how to use them.
Among the grubs which are injurious to potted plants are those which feed by root-feeding on living plants. As a result, they destroy the roots, the supply to the plant decreases and without countermeasures, an affected plant dies.
The larvae of the following beetle species are root eaters and are therefore harmful to potted flowers:
- Cockchafer (Melolontha) - larvae remain in the soil for up to four years
- Curlew Beetle (Amphimallon solstitiale) - Larvae remain in the soil for around two years
- Garden chafer (Phyllopertha horticola) - larvae remain in the soil for one year
If it is a plant with loose roots in the ground, collecting or picking it out can help in the event of an infestation. All you need is your own hands and some newspaper. If the soil and the root system have grown close together, this home remedy is not recommended because it promises little or no success.
This is how the collection technique works:
- Soil should be reasonably dry
- Pull root balls out of flower and plant pots over newspaper
- Shake off the soil carefully (the first larvae are already falling)
- Push pests out of the ground with your fingers
- Thoroughly search and proceed, as larvae are often found inside the bale
- If necessary, repeat every two days when unreachable larvae sitting inside have migrated to the outside
- Wrap grubs that have fallen off in newspaper and discard
If a hardy plant with strong roots is affected, flushing is another way to combat grubs. There are two different approaches: for a smaller infestation or for a severe infestation.
- Take the plant balls out of the flower pot and place them in a water bath
- Water level should skirt the entire bale
- If the bale fills up with water, the larvae rise to the top
- They float on the water surface and can be collected
- Quick collection is important so that they don't "flee" and reappear later
- Then drain the balls well and let them dry
TIP: This is also a great way to find out if there are any grubs in the soil at all if an infestation is suspected.
- Take the flower out of the pot
- Shake loose soil over newspaper or similar
- Dispose of first grubs on newspaper with this
- Hold the plant bales over the watertight container and "spray" them out with a strong jet of water
- If everything has been hosed down on soil, meticulously examine the roots for further larvae and collect or hose off
- Collect and dispose of all larvae!
TIP: Even if there are no grubs in the empty flower pot at first glance, eggs can still stick to the inner walls. Thorough rinsing with high water pressure or wiping should therefore be part of every grub fight.
Nematodes are tiny roundworms, also known as nematodes. Among them are species that transmit toxic bacteria. If they are eaten by beetles and their larvae, they die quickly. This method of fighting grubs is one of the most effective.
Appropriate nematodes, such as from the Heterorhabditis genus, are available in specialist garden/plant shops. Application is easy because they are contained in closed shells (usually made of clay) that moisture dissolves, releasing the nematodes. So they only have to be brought into the ground - either by folding them in or with the irrigation water.
Neem products are herbal ingredients extracted from the neem tree. This contains numerous natural insecticides that act against beetles and larvae, among other things, as well as acaricides that are mainly used against mites and ticks.
Neem, also known as neem, inhibits the development of the grubs so that they do not reach the next larval stage and reproduction is not possible. It also inhibits appetite, which prevents further damage to the roots. Although the larvae do not die immediately, their death is certain. NeemAzal has proven to be a suitable means of combating pests in flower pots. Neem is also available in powder form under other names. Both variants are placed in the ground.Neem tree (Azadirachta indica) with flowers
Actually, repotting is the safest home remedy for reliably fighting and getting rid of grubs in flower pots. However, each repot also means an additional strain on the flower/plant and can have harmful effects. Nevertheless, repotting can be life-saving for the plant, especially in the case of extensive infestation, if the roots are badly eaten away.
This is how it's done:
- Completely remove old soil and grubs from the roots
- Dispose of old soil with vermin immediately in a closed container
- Rinse/clean roots with light water pressure
- Shorten roots by 1/3 - this strengthens them and usually allows them to recover
- Also cut off damaged tissue and/or dead plant parts above ground
- Plant the plant in fresh substrate (it is essential to use a clean pot/flower pot)
- Pour lightly
- Fertilize after six weeks
Engerling decoy trap
During the winter, the decoy trap home remedy for fighting grubs is not suitable for indoor plants. This is due to the sensitivity to cold as well as the smell and hygienic reasons of the attractant in the house, because the trap is made of horse manure.
If an infestation is spotted in early spring/summer, indoor plants can be placed outside. Then the decoy trap is a reliable control measure against grubs, as well as for outdoor plants in tubs or flower pots.
That's how it's done:
- Fill the bucket with horse manure to about four inches below the rim
- Alternative to horse manure: rotted compost (not as effective)
- Dig the bucket into the ground up to the edge (about 40 to 60 centimeters deep)
- Fill in the soil and mark the location
- Place the flower pot/bucket in the immediate vicinity (ideally: right next to it)
- Horse manure attracts fresh/young grubs
- Bucket should remain in soil for four to six months to ensure larvae have migrated from last egg
- Larvae remain in the manure and can simply be disposed of with it
- Recommended: Always leave buckets buried from spring to autumn to stop subsequent generations
NOTICE: The decoy trap only works on young larvae. Older people remain unaffected and, if necessary, can be combated with another method mentioned here.