What Plants Need For Growth (1959)

[Music] here is a garden full of strong healthy plants these plants have had all the things they need to grow well do you know the things green plants must have to become as strong and healthy as the plants we see here first of all plants must have water you can give them water with sprinklers or you can water them with the fine spray from a hose but the best way for plants to get water is from the rain rain falls on the leaves and drips off onto the ground the water soaks into the soil and The Roots carry the water to the other parts of the plant you can do an experiment to show how important water is to a plant fill two pots with dry soil and plant seeds in each one now water one pot but leave the other one dry look at the pots each day and water the one labeled wet if it begins to get dry now we shall speed up the moving pictures so we can see the plants grow they do not really grow this fast here we are a week after planting the seeds you can see that only the seeds in moist soil are growing now perhaps you would like to give some water to the seeds in the pot with dry soil what do you will happen try it and find out you might also experiment with some plants that are older such as these tomato plants the plant on the left has been watered every day or two the one on the right has not been watered for nearly a week it has almost stopped growing we shall speed up the pictures again to see in a short time what really takes longer to happen the plant that didn't get any water is beginning to wilt now it looks as though it is dying let's give the wilted plant some water and see what happens there I guess we saved it but if we hadn't watered it for a few days more it would have died another thing green plants need is light the leaves of this nestum plant have grown so that they face toward the window now let's turn the pot around and see what happens with our pictures speeded up we can see the leaves turn and grow toward the light plants need light to be strong and healthy you can try this experiment in your classroom or home here is another experiment you can do to show that plants must have light plant an onion bulb in each pot and water them both but cover one of them with something that will keep out the light now one bulb will get light through the glass but the other will be in the dark look at the bulbs a few days later see how strong and green the lighted plant is and how fast it is growing the plant that had no light is yellow and unhealthy looking in this garden plot half of the plants have been shaded now let's remove the slat frame to see the plants that grew in the shade the Shaded plants are very small if we dig up the roots of a shaded potato plant we find only very small potatoes or no potatoes at all here is a potato from a plant that had full sunlight this beet plant grew in the shade this one grew in the sunshine here is a carrot that grew in the shade but this one was not shaded you can see that most green plants must have some sunlight do you know what this man is doing he is spreading fertilizer on his loan fertilizer improves the growth and color of the grass this man is putting fertilizer around his rose bushes his plants will grow big and strong and he will have many roses on the bushes there are minerals in fertilizer plants need these minerals to make good growth these tomato plants are growing in white sand there are hardly any of the minerals that the plants need even though the plants are watered they grow poorly and may die now let's mix some mineral fertilizer in water and see what it does for one of the plants growing in sand be sure to follow directions carefully because you might give the plants too much fertilizer too much fertilizer May harm the plants now we'll add mineral fertilizer to one of the plants growing in sand but only water to the other one watch them for a week or two and see which plant gets larger and healthier looking perhaps your plants will finally look as different as these do can you tell what fertilizer did for the one plant Farmers often use mineral fertilizers on their fields If plants do not grow well the soil may not have enough of the right kinds of minerals when it rains the fertilizer goes down to The Roots the Roots carry the minerals to other parts of the plant this man is spreading manure on his Fields dead plants and animal waste add many things that plants need for good growth besides water light and minerals plants must have air in each of these tin cans we have a small tomato plant one can has holes punched in it to let in the air extra water can get out through the holes when we water the soil in both cans we can see how water stands in the can with no holes standing water keeps out most of the air the roots of some kinds of plants can grow underwater others cannot a tomato plant soon stops growing when its roots are covered with water and it gets little or no air here are some plant roots growing in a glass faced box there is air in between the bits of soil when we pour on water the spaces in the soil fill up the air goes away Now The Roots stop growing the plants get sick and may die leaves must have air too green leaves in sunshine make food for the plant the leaves get water from the roots with water and air the green leaves make food making food from water and air is the most important and wonderful thing that leaves do one more thing plants need to grow warmth many kinds of plants die in winter but trees and shrubs do not die they only stop growing some of them keep their green leaves all winter we call them Evergreens this spruce tree is an evergreen other trees and shrubs lose their leaves in Autumn they may look dead but tiny new leaves are hidden in the buds when spring comes the buds swell and when it gets warm enough they begin to open by speeding up the moving pictures we can see the new leaves coming from this maple tree [Music] Bud the plants that died have left their seeds these sunflower seeds will fall to the [Music] ground now the seeds grow into new [Music] plants when you see plants and raise them yourself remember the things they need water light minerals air and warmth