Hardening off of passion seedlings

After grafting passion fruit seedlings, the next step is hardening off. This prepares the seedlings for the harsh conditions. It is a gradual process of acclimatising the young plants to outdoor conditions, ensuring they are strong and resilient.

Hardening off ensures the grafted seedlings develop tolerance to sunlight, wind and reduced water availability. It involves gradually reducing the shade and water supply in the nursery.

After grafting, it is important to maintain high humidity around the union. Cover the scion and the upper part of the rootstock with polythene bag. This ensures the graft remains moist, which is necessary for healing. Keeping the seedlings under shade also protects them from excessive water loss.

Watering should be regular, preferably in the morning or afternoon. Apply water directly to the soil. Excess water can lead to root rot or fungal growth around the graft union.

The goal is to ensure seedlings are hydrated but not waterlogged.

Another important task during hardening is pruning. Shoots that grow from the rootstock below the graft union should be removed, as these can divert energy from the scion. This ensures the grafted section receives the necessary nutrients.

When the scion begins to shoot, usually between 20 and 40 days after grafting, the polythene bag covering can be removed. The young shoots need to adjust to a less humid environment. However, the grafting tape may remain in place until vigorous growth is observed. The entire hardening off takes three to four months from sowing to the point the seedlings are ready for transplanting.

Success of grafting and hardening depends on several factors, including the health of the rootstock and the maturity of the scion. Rootstocks should be disease-free and strong. Scions should be taken from mature mother plants and matched with the rootstock’s cambium layer. Care must be taken to prevent water from entering the union, as this can lead to mould growth.

Once seedlings are hardened off, they should be carefully lifted from the beds or polythene bags to avoid damaging the roots.

The conditions in the field should be good enough to receive seedlings. Ensure planting holes are well-spaced and the soil has organic matter. Transplanting should be early in the morning or late afternoon to minimise shock caused by high temperatures and direct sunlight.

The seedlings should be watered thoroughly to help them settle into their new environment.

In our next article, we shall look at land preparation for Passion Fruits planting.

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