#48 - Apr 2021 - Garden Stuff - © - Sandy Lang - slang@xtra.co.nz
BIG TREES, LITTLE GARDENS April: Feels like autumn. Time to get your winter crops in the ground and plan next season. A large tree means no sun and rootbound soil. Maybe roots in your drains. Small trees: Ideally, small trees for small gardens. But dwarf trees can be weak, slow growing, or not the species you want. Bonsai: The ancients knew how to keep (potentially) big trees small (penjing, bonsai). Plants need root growth to produce hormones that travel up to stimulate shoot growth, which produces hormones that travel down to stimulate root growth. These opposite-going hormones work together to get a healthy balance between root and shoot. So, to stop a tree getting big you must continually prune both shoot and root. OK for bonsais but impossible for gardens. Or is it…? Root restriction bags: Heard of root restriction bags? Uncommon in gardens, commoner in nurseries/orchards. Root restriction bags are made of plastic felt (geotextile, used by road makers). Plant your (potentially) large tree in a root restriction bag in the ground. Its root system grows to fill the bag - and its shoot system grows in balance. Then: When the fine roots reach the bag, they find their way through the felt to the surrounding soil. But as they grow fatter, they are 'garrotted' by the strong felt fibres. This greatly slows or kills these escapees. Automatic root pruning…! But temporary root escapes continue, so root hormones continue to keep the shoot healthy. Ratios: Tree canopy volume is about 10-times root system volume. So, with a bit of shaping, a 40 L root restriction bag will help limit a tree to about 3 m high, and a 30 L bag to about 2 m high. Planting: Plant your new tree in a root restriction bag in a 1:1 mix of garden soil and potting mix. Then plant the bag in the ground with 2 cm of bag showing above the soil surface. Maintain an organic mulch on top and water it in a drought. Easier: A fruit tree in a root restriction bag needs less pruning, will be earlier and heavier cropping, easier to pick and easier to cover with bird net. Bonus: Your root restriction bag tree can also be transplanted easily. So, redesign your garden, relocate your tree, or take it with you if you move. More info? Root restriction bags are available in NZ from Evergrow Orchard there maybe other sources.___________________________________
BIG TREES, LITTLE GARDENS April: Feels like autumn. Time to get your winter crops in the ground and plan next season. A large tree means no sun and rootbound soil. Maybe roots in your drains. Small trees: Ideally, small trees for small gardens. But dwarf trees can be weak, slow growing, or not the species you want. Bonsai: The ancients knew how to keep (potentially) big trees small (penjing, bonsai). Plants need root growth to produce hormones that travel up to stimulate shoot growth, which produces hormones that travel down to stimulate root growth. These opposite-going hormones work together to get a healthy balance between root and shoot. So, to stop a tree getting big you must continually prune both shoot and root. OK for bonsais but impossible for gardens. Or is it…? Root restriction bags: Heard of root restriction bags? Uncommon in gardens, commoner in nurseries/orchards. Root restriction bags are made of plastic felt (geotextile, used by road makers). Plant your (potentially) large tree in a root restriction bag in the ground. Its root system grows to fill the bag - and its shoot system grows in balance. Then: When the fine roots reach the bag, they find their way through the felt to the surrounding soil. But as they grow fatter, they are 'garrotted' by the strong felt fibres. This greatly slows or kills these escapees. Automatic root pruning…! But temporary root escapes continue, so root hormones continue to keep the shoot healthy. Ratios: Tree canopy volume is about 10-times root system volume. So, with a bit of shaping, a 40 L root restriction bag will help limit a tree to about 3 m high, and a 30 L bag to about 2 m high. Planting: Plant your new tree in a root restriction bag in a 1:1 mix of garden soil and potting mix. Then plant the bag in the ground with 2 cm of bag showing above the soil surface. Maintain an organic mulch on top and water it in a drought. Easier: A fruit tree in a root restriction bag needs less pruning, will be earlier and heavier cropping, easier to pick and easier to cover with bird net. Bonus: Your root restriction bag tree can also be transplanted easily. So, redesign your garden, relocate your tree, or take it with you if you move. More info? Root restriction bags are available in NZ from Evergrow Orchard there maybe other sources.___________________________________