The GreenPlanet Horti Late Cal is the zero-nitrogen calcium source of the HORTI commercial line. It delivers bioavailable calcium and micronutrients through the late bloom phase, replacing Horti Cal so calcium stays in the feed while nitrogen comes out.
Calcium without the nitrogen
Late in flower, nitrogen slows a clean finish — but calcium still matters for bulking and plant health. Late Cal solves that by supplying calcium and micronutrients with no nitrogen at all. It pairs with Horti Late Bloom through the final phase.
How to mix it
Add 68 g per 100 litres (0.68 g per litre) during the late bloom, zero-nitrogen phase. GreenPlanet's targets are EC 1.8, pH 5.8–6.3 and a solution temperature of 18–23°C. Mix vigorously until fully dissolved — about 30 minutes. For run-to-waste systems aim for at least 10% runoff, and in the final 7 days flush with pH-adjusted water. See the HORTI AU feed chart (PDF).
Full specifications
| Manufacturer | GreenPlanet Nutrients (British Columbia, Canada) |
| Line | HORTI commercial line |
| Type | Dry, fully soluble calcium and micronutrient fertiliser |
| Nitrogen | None |
| Mix rate | 68 g per 100 L (0.68 g/L) |
| Targets | EC 1.8 · pH 5.8–6.3 · 18–23°C solution |
| Stage | Late bloom (zero-nitrogen phase) — replaces Horti Cal |
| Pairs with | Horti Late Bloom 0-24-26 |
| Feed chart | HORTI AU feed chart (PDF) |
| Size | 1.13 kg bag |
FAQ
Do I stop Horti Cal when I start Late Cal?
Yes. Late Cal replaces Horti Cal for the late bloom phase.
How long does it take to dissolve?
Around 30 minutes with vigorous mixing.
What about the last week?
GreenPlanet recommends flushing with pH-adjusted water for the final 7 days before harvest.