What makes green beans grow faster?
Written by
Tina Carter
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Want your green beans to grow faster? I know I do, and for 20 growing seasons, I've been doing what I can to coax true speedsters out of my soil. Faster growing means harvesting sooner and developing and producing for longer. You need to treat your soil, enlist helpers below the soil surface, and then control temperature. Do it correctly, and I mean correctly, and it won't be long before you taste your first bite off the plant weeks ahead of everyone else.
Thermal Management
- Lay black plastic mulch 2 weeks pre-planting
- Use water walls for thermal mass around seedlings
- Install low tunnels for early season planting
Microbial Enhancement
- Apply rhizobium inoculant directly to seeds at planting
- Brew compost tea with mycorrhizal fungi weekly
- Maintain soil pH 6.5-7.0 for optimal microbial activity
Pre-warm soil with black plastic mulch. Cover the beds for 10-14 days before sowing. The soil temperature is then measured at 5-8°C (9-14°F) warmer at a depth of 10 cm. I combine this tactic with clear plastic cloches after planting, creating a block of mini-greenhouses. Remove the covers when the plants come into contact with them, as they will scorch.
Nutrient starter - Apply phosphorus-rich starter right at planting, ideally 5-10-5 at 100g/m². In addition to phosphorus, other elements also stimulate root growth, earlier flowering, and larger fruit. For established plants, flush every 10 days with some fairly strong fish emulsion. Avoid high-nitrogen formulas, as the plants will expend their energy on growing leaves rather than developing roots.
Maintain perfect moisture: Drip irrigating and, on occasion, putting in a moisture sensor. Beans like their soil to be moist at 15-20 per cent volume all the time. You must place the sensor at the point where the roots are being fed. I tend to water in the dead of the night, with 2.5cm (1in) per week; more when they are in flower. You must mulch them, of course, with straw to cut down evaporation.
Use inoculants. To ensure a good nodulation, those who do not have good nodulation generally treat the seed with rhizobium powder before planting. This will produce root nodules up to 10 days earlier than a seed planted without treatment. To established plants, particularly legumes, a liquid inoculant can be applied to the soil. I have observed that inoculated plants outgrow untreated ones by 30% within three weeks.
Monitor progress using growth charts. Weekly height measurements are taken. Growth in healthy beans should be 2-3 cm per day. If you're behind, check the soil temperature and moisture now. I take a snapshot every week to monitor progress and make adjustments as needed.
Read the full article: When to Plant Beans for a Bountiful Harvest
