Depending on when you planted your cabbages, the hearts may not have formed yet. After planting out, there will be about 4-6 weeks of the plant putting out new loose leaves. After the first 4-6 weeks, you can expect to start seeing the leaves in the middle beginning to hold together more as they start to form the heart. This will become more pronounced over the next few weeks until the heart from quite a tight ball as you would hope. Harvest once the cabbages reach a good size, and before any signs of splitting (a crack can form, splitting the head – this usually happens after sudden heavy rainfall following a dry spell) or opening.
If you are worried about your cabbages not forming a heart, we would recommend the following things:
- Firm the soil down really well around the base of the plant – cabbages do much better in firm soil, so tread it down with your heel.
- Keep the plants well watered – they are cool-loving plants so making sure they are well watered will help to keep the soil cooler for their roots as well as obviously giving them better access to nutrients.
- Add a mulch – again, this helps to keep the soil temperature down. It also helps to keep moisture levels in the soil a little more even.
- Make sure plants are well spaced – if they are planted too closely together their leaves will shelter each other and prevent rain water from reaching the soil properly. 40-45cm is best.
Be prepared though, sometimes they just don’t form hearts, and if they got too hot at some point in the growing season you may find they have struggled. It is the way it goes in the veg patch, and you can always try again next year! We’d suggest leaving them in the ground for at least 3 months after planting, and if they still aren’t showing any sign of forming a heart, you can harvest and eat the looser leaves that your cabbages supply by shredding them up and treating them like spring greens in your cooking.