Advice and care
Describe what you see on the plant, or choose a common symptom.
Root and crown rot
Brown patches on the root crown, with the rot spreading into the roots; the plant wilts and dies. Young plants collapse (damping off).
Cause
Soil fungi, Thielaviopsis basicola, Pythium sp., Fusarium sp., Phytophthora sp. They are encouraged by waterlogging and contaminated substrate.
What to do
- preventive: do not overwater, ensure drainage, use uncontaminated substrate and healthy planting stock, treat seed, remove sources of infection
Viral diseases
Varied symptoms: mosaics, yellowing, vein clearing, necrotic spots, distorted or reduced flowers and stunted plants. Can be confused with a nutrient disorder.
Cause
Plant viruses; they are transmitted mainly by sap-sucking pests (aphids, leafhoppers, thrips) and by tools.
What to do
- preventive: healthy seed and planting stock, disinfection of tools, prompt removal and destruction of affected plants
- direct: focus on controlling the carriers (vectors)
Whitefly (glasshouse)
Small white flies that suck on the plants; they cause distortion and discolouration and excrete honeydew. Important vectors of viral diseases.
Cause
Glasshouse whitefly (Trialeurodes vaporariorum) and other whiteflies.
What to do
- direct: biological control, insecticide spray, sticky traps
Excess nitrogen
The plants grow lushly, are deep green and flower poorly. The tissues do not ripen properly, may suffer frost damage in winter, and the plants are more prone to disease.
Cause
Excess nitrogen, especially in ammonium form.
What to do
- do not overfeed with nitrogen; choose a balanced feed
- reduce nitrogen in autumn so that the tissues ripen
Scorch, sunburn and drought
Dry brown leaf edges and tips, dried-out patches; typical of newly planted plants, full sun and wind, or lack of water.
Cause
Scorch and incorrect (insufficient) watering; for outdoor plants, wind as well.
What to do
- in the first year, water regularly and generously, and mulch
- shade sensitive species or plant taller neighbours beside them
- cut off damaged leaves
Rose black spot
From May, brownish to brown-black spots of various sizes on the leaves; the leaves then turn yellow and fall, and the plant gradually weakens.
Cause
A fungal disease (Diplocarpon rosae). Encouraged by damp conditions.
What to do
- preventive: more resistant varieties, remove and destroy affected leaves, improve air circulation
- direct: fungicides (e.g. Discus, Dithane DG Neotec, Sylit)
Rust (on ornamental plants)
Orange to brown spore pustules, most often on the underside of the leaves; there may be yellow spots on the upper side. A heavy attack distorts and dries out the leaves.
Cause
Rusts of the genera Puccinia, Phragmidium, Cumminsiella and others. The hosts are roses and many perennials. They spread by water and wind.
What to do
- preventive: remove and burn affected leaves, reduce humidity
- direct: fungicides
Vascular wilt (Fusarium and Verticillium)
The plant wilts (even with enough water), the leaves turn yellow and dry up, and a cross-section of the stem shows browned vascular bundles. The fungus blocks the conducting tissues.
Cause
Fusarium spp., Verticillium spp., soil fungi that enter through the roots.
What to do
- preventive: healthy substrate and planting stock, disinfect tools, remove and destroy affected plants, do not grow susceptible species repeatedly in the same place
Damping off (Pythium, Phytophthora)
Young seedlings turn black and constrict at ground level, then flop and collapse; the roots and stem base turn brown and rot. Typical with waterlogging and dense sowing.
Cause
Soil-borne fungal organisms Pythium spp., Phytophthora spp., Rhizoctonia.
What to do
- preventive: open, uncontaminated substrate, thin sowing, careful watering (do not overwater), ventilation
- direct: e.g. Previcur Energy according to the label
Tospoviruses (INSV, TSWV)
Necrotic rings and line patterns on the leaves, blackening, stunting and distortion of plants. Widespread on ornamental plants in greenhouses.
Cause
Tospoviruses: impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV). They are transmitted by thrips.
What to do
- preventive: control thrips (the vectors), remove and destroy affected plants, check new plants
- viral diseases cannot be cured: prevention and removal of sources are the basis
Caterpillars (of butterflies and moths)
Irregular holes and bite marks in the leaves; in a heavy attack only the veins remain. Some species roll the leaves or mine them (tunnels). The caterpillars can usually be seen on the plant; tortrix moth larvae hide in rolled leaves.
Cause
Caterpillars of butterflies and moths (e.g. the tortrix moth Cnephasia spp.), looper caterpillars.
What to do
- direct: hand picking, biological control with Bacillus thuringiensis, insecticides while the caterpillars are young (instars 1–2)
- caterpillars have many natural enemies: encourage them
Cutworms (soil-dwelling caterpillars)
The caterpillars live in the soil and come out at night. They eat leaves and crowns at ground level, cut through young plants and also damage roots. During the day they hide at the base of the plants.
Cause
Turnip moth (Agrotis segetum) and related species.
What to do
- preventive: thorough soil cultivation, weed control
- direct: registered insecticides when young caterpillars are present; encourage natural enemies
Vine weevil / weevil (Otiorhynchus)
At night the adults eat characteristic curved notches in the leaf margins. The most dangerous, however, are the white larvae in the soil, which eat the roots and crown; the plant then wilts and dies (often begonias, primulas, rhododendrons and container-grown perennials).
Cause
Black vine weevil (Otiorhynchus sulcatus) and related species.
What to do
- direct: against the larvae, biological control with the parasitic nematode Heterorhabditis (watered into moist soil); against the adults, contact insecticides in the evening
- preventive: check the root balls of new plants
Fungus gnats (larvae in the substrate)
Small black flies hovering above moist substrate; their larvae nibble the fine roots of seedlings and young plants, which then wilt and fall behind, mainly in waterlogged substrate.
Cause
Fungus gnats (Sciaridae).
What to do
- preventive: do not overwater, let the surface of the substrate dry out
- direct: biological control with the nematode Steinernema feltiae and the predatory mite Hypoaspis, sticky traps for the adults
This is general information. When using plant protection products, follow the label.
Planting step by step
- Set out the pots by number
Do not plant anything yet. Set the pots out on the border exactly by the numbers in the planting plan, tall ones at the back (framework), low ones at the front (edge). - Check the spacing
Step back and look from above. There should be gaps between the plants. They will fill them once they have grown together. The recommended spacing is given for each plant (spacing in cm). - Photograph the layout
Before you start planting, photograph the border from above. If something does not fit, now is the time to move it, not after planting. - Plant in groups
Start with the framework (the tallest, at the back), then the filler, and finally the edge. Plant to the depth of the pot, firm in and water at the roots. - Water and mulch
After planting, water generously (~10 l/m²) and mulch the surface between the plants 5–7 cm deep. This holds moisture and suppresses weeds. - Note the planting date
Make a note of the planting day. We will use it to prepare a care plan for the first, most sensitive season.