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Crop advice for
Thuja occidentalis 'Smaragd'
General cultivation information, recommendations, tips & tricks
Best practice, suitable products and more for your Thuja occidentalis 'Smaragd'
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Thuja occidentalis ‘Smaragd’ is a widely grown conifer with a very universal use. The production in pots can be divided in two main branches: a culture that is fully grown in pots and a culture where field-grown Thujas are transferred into pots for the finishing stage. Our recommendation applies for the pot culture.
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Total cultivation time from cuttings to sellable plants is 2-3 years.
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Thuja occidentalis ‘Smaragd’ requires pH between 5.0 – 5.3 and constant moisture with no excesses. The substrate should be well-drained and easily re-wettable.
Thuja occidentalis ‘Smaragd’ requires pH between 5.0 – 5.3 and constant moisture with no excesses.
Thuja occidentalis ‘Smaragd’ does not grow very fast.
Stage 1: Cuttings
Make the cuttings ideally in late September – October, another option is between February – March. Artificial day length can stimulate quicker rooting during wintertime. Rooting is a crucial phase for Thuja. Cuttings require lower soil temperatures (Dec-Jan 14-15°C, Feb 16°C, March 17°C). In higher temperatures callus production can be limited! Avoid any EC peaks during this phase; maximum is 0.5mS during this stage. Also be careful with high amounts of urea. Do not use a water-soluble starter fertilizer for winter pottings.
Stimulate rooting with 5 g/m2 Peters Professional Plant Starter 10-52-10. Repeat this action before transplanting in April. When roots are developed a growth boost can be given with Universol Blue 18-11-18 10g/m2 (max 2x in 14 days). To finish the cutting phase Universol Violet 16-5-25 10g/m2/week can be given during the last weeks.
Stage 2: Vegetation (P9 cm -P11 cm)
The development of the roots and branches is the most important during this stage. Don’t focus too much on length. Increase the amount of fertilizer, once the plants have rooted successfully. Keep the EC low (0.5 mS) during the first 3 weeks after potting. Main growth happens in late spring and during September – October (November in southern countries). Keep the EC in the pot in these growth periods continuously around 1.0 mS/cm. Thuja occidentalis ‘Smaragd’ does not grow very fast. As plants are mainly grown outdoors, ensure a good base nutrition with Osmocote Exact Standard or Osmocote 5 mixed into the growing medium in the dose of 3 g/l. In summer period additional nutrition via irrigation is needed with 15-20 g/m2/week Universol Blue 18-11-18. Later in summer and autumn period change this to 15 g/m2/week Universol Basis 4-9-35 for strength and green color.
Stage 3: Finishing
Quality plants have a good length, shape, strength and deep green color. Thuja occidentalis Smaragd prefers low EC during the first month. Mix a base dose rate of 3 g/l Osmocote5 through the substrate when potting in early spring. Start from May/June with additional nutrition via irrigation with 20 g/m2/week Universol Blue 18-11-18. Switch from August to 15-20 g/m2/week Universol Orange 16-5-25 or to 15-20 g/m2/week Universol Violet 10-10-30 for finishing without additional growth. Do not use foliar feeding due to high amounts of urea as Thuja occidentalis ‘Smaragd’ is sensitive to urea. It can cause tip burn in combination with high irradiation.
Products
Use right products for each cultivation stage
Peters® Professional Plant Starter gives your plants the perfect start in life, so they form stronger, more uniform roots. Also great for stimulating flower bud development.
Universol® Blue is a pure and balanced formula that stimulates vegetative growth. Use as a follow-on from Universol® Yellow. It contains NPK, Mg and a full package of trace elements. The Bright Solution System dissolves the product fully and quickly.
Universol® Violet grants strong and compact growth. High potassium content delivers intense leaf color and great flower development. It contains NPK, Mg and a full package of trace elements. The Bright Solution System fully dissolves the product in no time.
Micromax® Premium B+Cu+Fe+Mn+Mo+Zn is a fine granular fertilizer with trace elements, essential for optimal plant growth. It ensures your plants get all the trace elements they need, whether in growing media or in field applications. Packed with a balance of six nutrients, the unique formula delivers a long-lasting supply of trace elements to your crops. This dust-free product is very safe in use, preventing toxicity symptoms. It is also environmentally friendly, with very low leaching of nutrients. It’s easy to apply and distribute evenly, plus it’s especially great for container crops.
Peters® Professional Plant Starter gives your plants the perfect start in life, so they form stronger, more uniform roots. Also great for stimulating flower bud development.
Universol® Blue is a pure and balanced formula that stimulates vegetative growth. Use as a follow-on from Universol® Yellow. It contains NPK, Mg and a full package of trace elements. The Bright Solution System dissolves the product fully and quickly.
Developed for application using A/B tank systems, Universol® Basis contains NPK, Mg and full trace elements. For hardening off plants, it can also be applied as a stand-alone product.
Ficote Total 5-6M is a 100% coated NPK fertilizer with a full trace-element package, with longevity of five to six months.
Take complete control of your late spring potting with Osmocote® 5’s controlled-release technology. This 5th generation programmed release fertilizer technology provides your plants with sustained, safe, and efficient nutrition over a 5-6 month longevity period. Achieve the best possible plant color, health, and growth by optimizing the availability and uptake of trace elements with the OTEA-system.
Universol® Blue is a pure and balanced formula that stimulates vegetative growth. Use as a follow-on from Universol® Yellow. It contains NPK, Mg and a full package of trace elements. The Bright Solution System dissolves the product fully and quickly.
Universol® Orange helps reducing plant growth’s speed. Higher potassium content is perfect for flowering pot plants and bedding plants. To balance fertilization, it can be applied if irrigation water has high N’s concentrations. NPK, Mg and a full package of trace elements. It dissolves fully and quickly thanks to the Bright Solution System.
Universol® Violet grants strong and compact growth. High potassium content delivers intense leaf color and great flower development. It contains NPK, Mg and a full package of trace elements. The Bright Solution System fully dissolves the product in no time.
Osmocote® 5 8-9M harnesses 5th-generation programmed-release fertilizer technology to help your plants achieve sustained, safe, and efficient nutrition over an 8–9-month longevity period.
Guides & Articles
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Q&A
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Unlike some other Thuja occidentalis cultivars, Smaragd is not a massive grower. Therefore, it is important to limit the application of water and fertilizers. Always separate Thuja occidentalis ‘Smaragd’ in your nursery from, for example, Thuja occidentalis ‘Brabant’, because their needs are different.
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Thuja occidentalis ‚Smaragd‘ cuttings can suffer from the larvae of Sciara flies because it takes them a few months to root. Also Wine Weevil (Othiorhynchus sulcatus) larvae can invade the pots. Mix protection products preventively into the substrate. Sometimes aphids occur on branches of older plants during springtime. Take care as these pests are difficult to recognize.
Fungal infections (Pestalotia, Dydimella, Kabatina) can cause various twig diseases in Thuja occidentalis ‚Smaragd‘. Avoid stress during pruning periods to reduce the infection risk. If needed use chemical protection.
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